SAN ANDRÉS, Colombia — Nearly 50 years after she first put on a wetsuit, Elvira Alvarado still remembers coming upon a coral reef off Colombia's Caribbean coast.
"Everything was alive. And it was green and bright orange. And there were fishes. And there were huge things. And they were corals. It was astonishing," she says. "Can you imagine paradise? It's paradise."
At 70, Colombian marine biologist Elvira Alvarado is still diving, researching and training a new generation of scientists. Her mission: rescuing Colombia's endangered coral reefs by reproducing coral through in-vitro fertilization. Her lifelong dedication to these marine invertebrates has earned her the nickname: "the mother of Colombian corals."
Coral are vital ecosystems that provide food, shelter and breeding grounds for some 4,000 fish species. They protect shorelines from erosion. They even support tourism by attracting snorkelers and divers.
However, diseases, pollution and rising ocean temperatures are taking a huge toll. Since the 1970s, more than half of all the coral in the Caribbean have died.
"I saw them dying. I saw them turning white," says Alvarado from the Colombian island of San Andrés in the Caribbean Sea, where many of the once exotic, garden-like coral reefs are now barren.
Juliana Vanegas, a marine biologist who works with Alvarado, explains what happens.
"The coral are still alive, but when they are bleached and are not feeding, they start to get weaker and weaker," she says. "And if that lasts for enough time the coral die, basically of starvation."
In addition, coral weakened by disease or overheated water have a much harder time reproducing. So, here on San Andrés, Alvarado and her team of about a dozen divers, decked out in scuba gear, are lending a hand through in-vitro fertilization, or IVF.
The technique was pioneered by Australian scientist Peter Harrison. It involves collecting coral eggs and sperm, fertilizing them in a laboratory, then transplanting them to existing reefs. Alvarado has become Colombia's most energetic proponent of the technique.
"We can't stop what is happening," she says, referring to climate change and highly lethal threats like Stony Coral Tissue Loss Disease, which was first reported in 2014 and has spread throughout the Caribbean. "But we can try to replace coral that's dying."
Alvarado was first drawn to the ocean by television. As a young girl living in the U.S. she was fascinated by programs like Sea Hunt and Flipper, about a bottlenose dolphin that outsmarts most of the humans on the show.
She moved back in Colombia in the 1960s to became one of the country's first female marine biologists to focus on coral reef restoration. Along the way she got to meet Jacques Cousteau, the world's most famous oceanographer who visited her university.
"We sat down, and he was talking to me. It was a dream," she says.
Alvarado was a natural underwater. She learned to free dive — without air tanks — to a depth of 72 feet. She initially did cancer research involving sharks. However, as coral began dying off, she focused on reef restoration by growing new coral.
Timing is everything. Coral spawn just once a year, about a week after the full moon. That gives Alvarado's team here on San Andrés just a tiny window of opportunity to dive down and collect coral eggs and sperm.
Alvarado moves gracefully underwater. Some 30 feet down, she and her team place nets with collection tubes around selected coral. Then, after dark on a second dive, they check the collection tubes. Last night, they came up empty. But tonight's a different story.
"They've spawned," yells an ecstatic Alvarado, who then rushes off to a makeshift laboratory.
There, she and the team mix together eggs and sperm and place them in water-filled plastic tubs. Under a microscope, they appear creamy white in the shape of raspberries. Soon, the coral hatchlings will be placed in seaside nurseries for 6 to 12 months then taken back to the reefs.
And because the team has gathered genetic material from coral that appear more resistant to heat and stress, their efforts are designed to reproduce hardier varieties. The trick, says Alvarado, is to regenerate coral faster than they die. But she's also realistic.
While coral reefs will not be as diverse as they were when she first started diving in the 1970s, she says: "We will have reefs that are resistant to the warming conditions."
She's also proud to have mentored scores of young marine biologists — mostly women — who all seem to adore her.
"She's a very inspiring woman," says María Fernanda Maya who heads the Blue Indigo Foundation that works to restore reefs. "She's the mother of coral in Colombia."
That's why, when Alvarado finally does hang up her swim fins, her legacy will live on.
"When I started this, we were just three people — two students and me. And look what we've got now," Alvarado says. "This will continue even after I'm dead. That's the good thing."
Copyright 2025 NPR
