Miami Scientists Plant Crossbred Elkhorn Corals to Fortify Bleached Reef

Divers this week planted dozens of crossbred Elkhorn coral fragments on a reef off Key Biscayne, the first time corals bred from international parent stock have been approved for placement on a wild U.S. reef. The work is part of a project led by the University of Miami’s Rosenstiel School, the Florida Aquarium and Tela Marine in Honduras to bolster Florida’s rapidly declining coral populations. Scientists cross-fertilised spawn from Florida Elkhorn corals with eggs and sperm collected from a reef near Tela, Honduras, where seawater runs about 2 °C warmer. The offspring were reared at the Florida Aquarium and fixed to small concrete bases on the damaged reef on 1 July. Researchers will monitor the hybrids throughout the summer to see whether the Honduran genes confer greater tolerance to heat stress than native Florida corals. Florida has lost more than 95 % of its Elkhorn corals since a severe bleaching event in 2023, leaving coastlines increasingly exposed to storm surge. Because Elkhorn colonies form the crest of the reef that acts as a natural seawall, the team hopes the experiment will provide a template for restoring climate-resilient reefs across the Caribbean.