The experiment at the edge of Tampa Bay began four years ago.
Scientists who feared the worst for Florida's endangered coral reef believed the creatures could reproduce more safely in a controlled setting and later be returned to their natural habitat to rebuild the reef.
There was little early success. But today, on the aquarium's 20-acre Center for Conservation campus in Apollo Beach are two 1,500-square-foot coral nurseries teeming with life.
"We've made the right changes needed to recreate the ocean in an aquarium," said nursery manager Keri O'Neil, citing light and water temperature as examples. "It takes time to get it right, but once we are dialed in we can start cranking coral out by the thousands."
Each summer, the Florida Aquarium sends divers to the Florida Keys for the annual spawning of the coral.
The collected spawn is taken to a lab in the Keys to have genotypes mixed and matched. Some is released back into nature and the rest is raised in the Apollo Beach nurseries that the aquarium calls arks after the biblical boat that saved two animals of each kind.
In 2014, one coral baby survived. It now resides in the downtown aquarium.
None did so in the next two years.
Then in 2017, around 2,500 larvae settled on rocks in an ark tank. Of those, 119 staghorn corals, 213 elkhorn corals and 131 mountainous star corals are still alive and growing, each at around four inches high.
From the 2018 mission to the Keys, more than 5,000 staghorn larvae and 30 pillar larvae settled. The aquarium is confident that batch will exceed the 2017 percentage that survived.
To house these corals, the second ark was completed in July. Ultimately, another six are planned, if funding is available. They cost between $250,000 and $300,000.
"Our responsibility is to do what we can to protect and restore the blue planet," aquarium CEO Roger Germann said. "Coral reefs are a priority."
Extending 360 miles from the St. Lucie Inlet in Martin County to the Dry Tortugas in the Gulf of Mexico, about 67 miles west of Key West, the Florida Reef Tract is the world's third largest barrier reef.
It protects that coast by reducing wave energy from storms and provides the entire state with an important ecosystem.
According to the National Oceanic and Atmospheric Administration, coral reefs support more species per unit area than any other marine environment.
"You may not miss the reefs until they are gone," nursery manager O'Neil said.
Since the 1970s, half of the coral cover in Caribbean waters has died, according to a study by the International Coral Reef Initiative.
Coastal pollution and global warming have long been decimating it. And, for the past few years, a mysterious disease has been killing the reef.
First reported in 2014 near Key Biscayne, the disease has since spread to Looe Key, in the Lower Keys and is estimated to have resulted in the mortality of millions of corals by killing their tissue. The cause is still unknown.
O'Neil hoped to return some of the one-year-olds to the Florida Keys this year but is hesitant because of the disease.
The aquarium is taking an added precaution in case the disease or other factors wipe out a type of coral before captivity growing is perfected.
Like a worm, if coral is broken into pieces, each fragment survives as its own organism. To create a genetic archive, aquarium scientists have taken fragments of different adult corals from the wild and replanted these in the arks' tanks.
There are 24 such staghorn corals and 119 pillar corals.
"We are giving them a place to weather the storm," O'Neil said.
Still, while the process can rebuild the dying reefs by replanting that coral in the wild, it cannot be the savior.
"Those come from the same coral so have the same genetic makeup," O'Neil said. "If it is susceptible to another disease outbreak, it would all be wiped out."
But when creating coral through sexual reproduction, each baby has a different genetic makeup.
"The hope is that through the process of nature," O'Neil said, "some will be stronger at resisting different stresses."
Contact Paul Guzzo at email@example.com. Follow @PGuzzoTimes.