VEGA BAJA, PUERTO RICO – Ricardo Laureano suspected that the elkhorn corals in El Eco Reef in northern Puerto Rico were special. In his 16 years of protecting and monitoring their growth, the self-described coral worker has seen only a few cases of bleaching, a problem that is increasingly plaguing corals worldwide. Scientific findings prove Laureano right. The reef it protects is key to combating the effects of climate change on the archipelago.
A 2024 marine and environmental archeology study suggests that the El Eco reef has survived since pre-Hispanic times, possibly due to a genetic variation that makes the coral resistant to bleaching. Bleaching occurs when rising water temperatures force corals to expel photosynthesizing algae, causing reefs to appear ghostly white. Local scientists now believe El Eco’s corals could help repopulate faded reefs – and mitigate other climate-related disasters.
“It is Puerto Rico’s newest jewel in coral conservation,” says Edwin Hernández, senior scientist at the Marine Environment Society, an organization dedicated to reef restoration in Puerto Rico.
At first glance, elkhorn coral looks like an underwater hand reaching toward the sky. As one of the most important corals in the Caribbean, it provides habitat for many species and its rapid growth and location on the reef allow it to withstand wave action. The species has been listed as “threatened” under the United States Endangered Species Act since 2006, and as global temperatures rise, their populations are more at risk than in the past. It resists bleaching better than other species and shows signs of branching and resistance to higher temperatures, but cannot quite surpass it.
In 2023, the Caribbean experienced the worst coral bleaching mortality since 1987. By October, over 95% of Puerto Rico’s corals had been affected by mass bleaching, described in the Marine Environment Society’s technical reports as an “unprecedented” marine heat event.
Hernández says all the elkhorn colonies died in Cabo Rojo, on the southwest coast of the archipelago. In other areas only isolated populations survived. But in Vega Baja, home to El Eco Reef, coral mortality was just 1.7%.
Climate anomaly
Mariela Declet, marine biologist and environmental archaeologist, draws on history to explain the resilience of El Eco corals. Through zooarchaeological analysis examining animal bone remains, Declet found that centuries ago this coral survived temperatures similar to those seen today.
Between 800 and 1300 AD, the Northern Hemisphere experienced temperature fluctuations and a high frequency of hurricanes. There is evidence of a massive coral bleaching event between 900 and 1000 that affected the north and south coasts of Puerto Rico. But as Declet describes in her doctoral thesis at the University of California, the El Eco corals managed to adapt and survive.
Between 2008 and 2019, around 14% of the world’s reefs were lost to bleaching. If conservation measures are not taken, scientists predict that 99% of these ecosystems could disappear by the end of the century. This would mean a loss of habitat for 25% of known marine species, the collapse of the fishing industry and greater stress on coastlines by the power of the ocean.
Nearly 200 million people worldwide rely on coral reefs to protect themselves from storm surges and waves, as these ecosystems can reduce wave energy by 97% and wave height by 84%.
According to a 2019 study by the United States Geological Survey, coral reefs protect an estimated 18,000 people from flooding each year in the United States alone and prevent around $825 million in damage. The same document shows that without coral reefs, Puerto Rico’s main island would face the worst flooding in U.S. territory.
For Declet, the resilience of El Eco’s elkhorn corals offers “a sense of hope” for the species’ conservation and reproduction.
In 2023, Vegabajeños Impulsando Desarrollo Ambiental Sustentable (VIDAS), a volunteer organization led by Laureano, transplanted some of the El Eco corals to El Escambrón Beach in San Juan. Hernández, who monitors the area, says the specimens have begun to branch and are resistant to high temperatures.
This exercise could be repeated in other areas of Puerto Rico’s capital to prevent flooding. In 2023, the Federal Emergency Management Agency approved $3 million under the Hazard Mitigation Grant Program for the first phase of reef restoration off the coast of San Juan. Nilda Jiménez, coordinator of the Endangered Species Program at Puerto Rico’s Department of Natural and Environmental Resources, says the department is considering El Eco corals for the project.
But scientists acknowledge that success is not guaranteed given the rapid rise in ocean temperatures. “At this rate,” says Declet, “we don’t know what will survive and what won’t.”
In October, bleaching occurred in El Eco due to high water temperatures, Hernández says. According to his preliminary estimates, about 5% of the coral population died.
Protect reefs
Although El Eco corals are resilient, that doesn’t mean they always will be, warns Jiménez. She believes it is necessary to continue to identify resistant coral colonies and focus on protecting reefs.
A 2022 study from Rutgers University, the Coral Reef Alliance and other institutions concludes that preventing water pollution, avoiding overfishing and eliminating other risk factors will help resilient strains develop and other reefs recover colonize.
In August of this year, the government of Puerto Rico signed a law declaring El Eco Reef part of the Vega Baja and Manatí Submarine Gardens Nature Reserve. The measure guarantees $1 million in annual funding to protect elkhorn coral and other species. VIDAS’ Laureano also aims to promote genetic variability studies and monitor water quality and temperature to prevent reef degradation, among other initiatives.
José Antonio Vargas, the senator who introduced the reef protection bill, told the Global Press Journal that the reserve’s designation would allow “a special level of care” for the elkhorn coral.
Meanwhile, Laureano, along with other volunteers from Vega Baja, are still committed to protecting the reef. Now that he knows why the corals he has cared for over the years are so resilient, he has redoubled his efforts.
“I don’t think we own the copyright to the super corals of Vega Baja,” he says. “It would be nice to help more people.”
