Twelve Organizations Race to Save Florida's Coral Reef During a Once-a-Year Spawning Window

Coral spawning happens once a year, in a narrow window set by lunar cues and environmental conditions; corals release millions of egg and sperm bundles together, which must meet bundles of the same species in the water for fertilization to occur. But after decades of decline, elkhorn and staghorn coral colonies on Florida's Coral Reef have become so sparse, fewer than 150 unique elkhorn corals and 300 staghorn corals remain, about 1% of their former abundance, that natural reproduction has grown increasingly difficult.

During the first week of August, 12 organizations, including the University of Miami Rosenstiel School, Mote Marine Laboratory, Reef Renewal U.S., The Florida Aquarium, The Reef Institute and the Smithsonian Marine Station, coordinated an assisted-fertilization effort at offshore nurseries near Key Largo and a temporary lab at John Pennekamp Coral Reef State Park. Dive teams collected gametes, researchers determined desirable genetic crosses to fertilize embryos likely to withstand environmental stress, and a separate team cryopreserved sperm to preserve genetic diversity for future restoration.

Over seven days, scientists observed 25 elkhorn and 36 staghorn genotypes spawning, carried out 116 unique directional crosses, and produced more than 1.5 million embryos, yielding over 61,000 elkhorn and 47,000 staghorn larvae, now being raised across the participating institutions. "Our reef is in trouble, and we need to take urgent action to scale up efforts to help restore and rebuild one of the state's most valuable environmental and economic resources," said Andrew Baker, the project's principal investigator and a professor at the University of Miami Rosenstiel School.

Within two years, the organizations plan to return the resulting young corals to the same nurseries before transplanting them to reef sites, including locations in the Florida Keys National Marine Sanctuary's Mission: Iconic Reefs program and the Kristen Jacobs Coral Aquatic Preserve.