Keri O’Neil, senior coral scientist, Center for Conservation at the Florida Aquarium (The Florida Aquarium)

The Fate of This Coral Species Rests in a Dark Room in Tampa

Scientists have coaxed Atlantic pillar corals to spawn in captivity for the first time—a breakthrough that could save the species from extinction.

October 28, 2019

On Saturday, August 17, something took place that had never taken place before. In a darkened room on Florida’s Gulf Coast, a captive population of about 30 Atlantic pillar corals spawned in synchrony.

“The males went first,” says Amber Whittle, director of conservation for the Florida Aquarium in Tampa. “They just kind of released this cloudy, white sperm. It looked like someone had put milk into the water.”

Five minutes later, right on cue, the females did their thing, discharging thousands of tiny egg bundles that turned their tanks into living snow globes.

“This is a game-changer,” says Whittle, whose team spent two years planning for this moment and months tweaking water temperatures and light exposures to make it happen. Under normal sea conditions, these sperm and eggs would meet just once a year in a precisely timed orgy that occurs just after the August new moon.

But only 50 Atlantic pillar coral colonies remain in the waters off Florida, living too far apart for their reproductive cells to ever cross paths. This means that the coral species, whose formations resemble stalagmites found on a cave floor, isn’t just threatened, per the National Oceanic and Atmospheric Administration, or vulnerable, according to the International Union for Conservation of Nature. It’s what scientists call “functionally extinct.”

Project Coral Laboratory, the Florida Aquarium

The Florida Aquarium

In other words, the handful of corals that were recently coaxed into spawning at the Florida Aquarium are very likely the only reproducing Atlantic pillar corals left on earth.

Stony corals like the Atlantic pillar provide the base for the Great Florida Reef, North America’s only barrier reef. This 170-mile structure, which extends from Key West to points (in patches) north of Palm Beach, is home to almost 1,400 species of marine plants and animals. While scientists have managed to breed other corals in captivity, such as staghorn, elkhorn, and some Pacific species, no one had found a way to set the right mood in the laboratory for Atlantic pillars.

The sexual breakthrough came just in time. Atlantic pillar corals and the Great Florida Reef are under rising threat from a convergence of nastiness: pollution, overfishing, climate change, and disease. Pollution is a huge coral killer and comes in many forms, from fertilizer runoff and sewage overflows to sedimentation from development. Overfishing depletes reefs of their grazers, such as parrotfish, which keep the algae that can suffocate corals in check. When those fish disappear, so do the corals that depend on them.

The Florida Aquarium

Climate change is another member of the rogue’s gallery—perhaps even the archvillain. Coral polyps are animals, and their health depends on their symbiotic partnership with zooxanthellae, single-celled organisms that live within their tissues and help nourish them through photosynthesis. The protozoans also give corals their vibrant colors. When warming sea temperatures stress corals, they expel these helpful inhabitants, which causes them to turn ghostly white and become more susceptible to disease. This is coral bleaching, and in recent years it’s been wreaking havoc on reefs all over the world.

And then there is stony coral tissue loss disease, SCTLD, or “skittle-D” as some call it. The outbreaks began near Miami in 2014 and have since spread as far north as Palm City and as far south as the Lower Keys.

Scientists think the disease is spread by bacteria, which cause the corals’ tissues to fall off and expose bony white patches that are then susceptible to algal growth. In the end, skittle-D can be fatal, and NOAA estimates it affects nearly half of the stony coral species that inhabit the Great Florida Reef, including the Atlantic pillar.

This is yet another hurdle to the pillar’s recovery. Even though Whittle and her colleagues have started growing new corals by mixing the eggs and sperm of those that have spawned, the effort to return these rocklike creatures to the wild hinges on finding suitable habitat to return them to. “We can’t put our babies back into where they were getting diseased,” says Whittle.

Florida Keys NOAA Gov

The good and bad news is that stony corals grow very slowly. In fact, Whittle says they’re thought to be the oldest living animals in the United States, with some colonies estimated to be more than 1,000 years old. What it means for the new crop of young corals is that they are so small, you can really see them only through a microscope.

They also require a lot of care. At this stage, Whittle says, the corals are susceptible to getting smothered by algae growth. To prevent this in the lab, the scientists must peer through microscopes as they scrape tiny specks of algae away from the corals with the tip of hypodermic needles.

The team estimates it will be at least a year, and quite probably even longer, before they will feel comfortable introducing any of their tiny charges to the wild—the ultimate goal. In the meantime, Whittle says they’re still trying to pinpoint the optimal environmental cues to trigger spawning so they can get the corals to turn their aquariums into gamete snow globes more than once a year. So far they’ve been using data from a government buoy to mimic conditions out at sea—re-creating in real time sunrises and sunsets and the waxing and waning of the moon’s glow.

“They’re not producing in the wild, so we need to produce them on land,” says Whittle. “And this is the way to do it. This is the way to make lots and lots of them.” The Atlantic pillar coral’s fate and strength through genetic diversity lie in humanity’s hands—as does the health of the rest of the Great Florida Reef.

“This is really a big deal,” Whittle says.


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