Reef rescuers race against climate change
Ten years ago, when scientists in South Florida began a massive rescue effort to rebuild the nation's only inshore reef, replanting nursery-grown staghorn coral with a gardening technique perfected in the Pacific seemed like an easy solution.
“You can go to Home Depot to get everything you need,” said University of Miami marine biologist Diego Lirman. “And you don't need to pay for this. People pay us to come out.”
From Key West to Fort Lauderdale, volunteers and scientists planted thousands of staghorns in reef rescues. More than 90 percent of Lirman's corals survived — about 10 percent more than expected — signaling a rousing success. The work helped shift reef restoration from uglier, more costly engineered artificial reefs created with scuttled ships, which are also more susceptible to invasive species and vulnerable to sea rise. Labs expanded to meet the growing demand, added more kinds and perfected techniques.
Then came back-to-back bleaching events that started in 2014. In 2015, more than half of Lirman's transplanted staghorns died. Suddenly, the reef gardeners were faced with a daunting new obstacle: climate change.
With ocean temperatures rising in the last century, and consistently higher than ever before over the last three decades, scientists realized replanting nurserygrown versions of wild coral would not be enough. They would need to weed out the weak coral, find a way to make the gardengrown variety more resilient to both temperature and rising acidity linked to more carbon in the atmosphere, and work faster. Much faster. Welcome to Rescue a Reef 2.0. What started as a citizen science project to rebuild the reef is now an all-hands-on-deck dash to not only replant but develop a crop of tough new coral with cutting-edge science.
In April, the National Oceanic and Atmospheric Administration signed off on a two-year project with UM to rebuild the reef, and one of South Florida's economic engines, with 10,000 corals grown in Lirman's lab. Last month, Mote Marine Laboratory opened a new 19,000-square-foot, $7 million lab on Summerland Key. And in August, Andrew Baker, another UM coral expert working with Lirman, will begin replicating a hardening method developed in his lab. Baker was also selected as the new Frost science museum's first inventor-in-residence and will display the ongoing efforts in a new public lab at the downtown museum.
“We've done it in the lab,” Baker said. “Now we need to see if we can do it in the real world and scale it up.”
Scale was in fact one of the dilemmas that led to the early advances in coral gardening. When he started working with the Nature Conservancy 10 years ago, Lirman's goal was to save the staghorn coral thickets that in just 30 years had largely disappeared. Pollution, boat traffic and overfishing had wiped out many that grew along the coast. Hardly any elkhorn corals, another oncecommon variety, were left. Both, which are federally listed as endangered, are branching coral that provide habitat for wildlife and helped build more reef volume. In low-lying South Florida and across the Caribbean, that can be critically important.
Reefs not only help break-up fierce hurricane waves but, more importantly, subdue everyday waves that erode beaches, which has cost taxpayers millions in South Florida. Last year, the U.S. Army Corps of Engineers spent $11.9 million just to shore up beaches in Miami-Dade County. It spent $7.1 million in Broward in 2013.
But Lirman needed to find a way to grow enough staghorns without poaching too much from the little that was left. So he collected 30 samples, enough for diversity. As disease and bleaching occurred, he was able to look more closely at the genotypes that fared better and focus on those.
“My nursery is now replanting close to 5,000 corals each year on 15 to 20 sites in Miami-Dade,” he said, which amounts to “ecologically relevant scales.”
If his field trial works, Baker said it's possible to replicate the hardening elsewhere in the world, like the Great Barrier reef, where an ongoing bleaching has ravaged an area larger than Italy and covering two-thirds of the reef.