A reef site intact elkhorn coral stand at Curaçao (Photo by Paul Selvaggio, Pittsburgh Zoo & PPG Aquarium)

Ocean coral is a lot like humans in at least one respect. Stress kills its sex drive, causing fertility rates to nosedive, and with it the production of coral.

And coral is under a lot of stress these days — a disease outbreak from the 1970s is a continuing threat; city sewer outfalls spit waste into their habitat; overfishing eliminates animals that graze on harmful algae; and higher acidity levels from global warming eats away reefs. Ninety-eight percent of critically endangered elkhorn Caribbean coral is gone.

That's the bad news.

The good news – from research published recently in the Bulletin of Marine Science – is that scientists have engineered a breakthrough that, fingers crossed, could one day restore the a key species of coral.

Long story short, a research team went to Curaçao, waited for a variety of coral species to predictably fertilize eggs after the first full moon in August, took the microscopic eggs to an offshore lab near the capital Willemstad, and grew them to adulthood. The speed of their growth, one year, blew their minds. "We thought it took much longer," said Dirk Petersen, director of SECORE International in Germany, a participant in the study.

The team returned several pieces of coral that had grown to the size of a soccer ball to the reef where they were extracted, and last year, again after that August moon, observed two of them releasing eggs and sperm. This, Petersen said, was a big deal. This type of restoration had never been achieved before, even on such a minor scale.

Coral reefs are biodiversity hot spots, important to billions of organisms living on land and in the sea. They are called the rain forests of the ocean, comprising only 1 percent of life in there, but drawing a quarter of everything that lives to them. Those things include the fisheries that feed 500 million people in 94 countries and territories. Their economic value is estimated at $375 billion per year.


Elkhorn coral may reach a size of several meters in diameter. (©Paul A. Selvaggio)

What's more, coral reefs buffer waves, providing a sanctuary to marine life that would perish from being constantly tossed and turned. They also blunt angry storm surge, waves whipped into a frenzy by high winds. Coral reduces catastrophic flooding in cities and towns.

"What we’ve done is shown we can help these endangered coral through this delicate step in their life history," Petersen said. In addition, the lab-generated coral could possess a genetic structure that allows it to tolerate the stresses that plague existing coral. "We have created new genetic individuals… that can reproduce by themselves and possibly create genetic individuals that can tolerate this environment," Petersen said.

It was important to bring together "aquarists" and scientists to finally achieve this result, said Mike Brittsan, director of aquatic science for the Columbus Zoo and Aquarium in Ohio. "Scientists understand the biology, but aren't good at keeping things alive. We know how to keep things living," Brittsan said.

Brittsan said he first started collecting eggs with Petersen in 2006, fertilizing them and getting them to grow in ways that no one had before. Eventually they went to Curaçao because of the massive genetic diversity of coral there, despite the effects of disease and other pressures.

Coral reproduces two ways, asexual and sexual. Asexual production is when a piece breaks off and lands in a lucky place where it can continue to grow without any change genetically from the host. But sexual reproduction promotes the genetic diversity needed for the survival of a species.


Egg-sperm bundles break apart as lab in-vitro fertilization occurs (Photo by Paul Selvaggio, Pittsburgh Zoo & PPG AquariumPhoto by ©Paul A. Selvaggio)

"If you have one species and something wipes it out, end of story," Brittsan said. "But through genetic diversity, some are saved."

Mark Schick, the collection manager for the John G. Shedd Aquarium in Chicago, said scientists didn't waste time getting started. Using a variety of grants from the Smithsonian, the National Oceanic and Atmospheric Administration and aquarium-related foundations, they are seeding reefs in Mexico, the Bahamas and Curaçao, he said.

In the lab, researchers use a device called the Kreisel — German for spinning top — that imitates the motion of the ocean for 200,000 larvae in the size of a very large salad bowl, Schick said. It keeps them alive in the lab and makes them accustomed to life in the wild.

"We're randomly placing young coral on reefs… with very little effort and very little financial output," Schick said. "Every year we do this we see a way to tweak it."

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