Scientists racing to save coral from bleaching are running out of space
Scientists hoping to provide a genetic lifeline to Florida’s ailing reef are removing hundreds of colonies of healthy coral off Miami, hoping to outpace a wave of lethal bleaching spreading from the Florida Keys.
About 400 colonies have been moved by University of Miami Rosenstiel teams in the last week to tanks at the school’s fish hatchery on Virginia Key — but space is quickly running out.
“You have to realize that we're only rescuing a fraction of our stocks where we're saving key genotypes,” said marine biologist Diego Lirman, whose Rescue A Reef lab oversees two nurseries off Key Biscayne. “We’re leaving out there thousands of corals that we have nowhere to put.”
Over the last month, as an ocean heat wave dragged out, stressed out coral began bleaching across the Florida Keys. Bleaching occurs when coral undergo prolonged heat and light stress.
By last week, famed dive sites including Sombrero Reef and Cheeca Rocks in the Middle and Upper Keys suffered all or near total bleaching. Dead corals included slow-growing boulder coral that provide a reef’s foundation and faster-growing staghorn.
“Cheeca Rocks is worse than I expected,” National Oceanic and Atmospheric Administration coral scientist Ian Enochs told WLRN via text after diving at Cheeca earlier this week. “100% of corals are affected. Every. Single. One.”
This latest bleaching is a dire hit to the only inshore barrier reef in the U.S. mainland. Florida's 350-mile long reef has declined dramatically since the 1970s and is now shrinking faster than it’s growing.
Since 2014, an outbreak of a new disease scientists believe was transported in ship ballast water began quickly spreading from off Virginia Key.
As old mounding coral died up and down the reef, the stony coral outbreak triggered an emergency response that drew scientists from around the country. It also expanded rescue operations previously used at a smaller scale for moving coral to labs ahead of bleaching, dredging and other threats. In 2014 and 2015, back-to-back bleachings wiped out about half the coral at UM’s nursery off Key Biscayne.
Now, with climate change expected to make ocean heat waves more common, scientists say onshore facilities need to be expanded and rescue work scaled up to accommodate bigger and more frequent emergencies.
“We're filling up as much of the tank space here as possible. I brought tanks online two weeks ago to make space available for this,” said marine biologist Cameron McMath, the facilities manager at UM’s Coral Reef Futures lab.
“A lot of what we've been doing to prep for this is shuffling around what we've got, putting it in spaces that can hold it so that we have available space for the corals coming in. At some point they're going to run out of space. But we can't worry about that until we get there.”
Moving, cleaning and tagging the coral
On Tuesday, students in both labs hustled around the noisy outdoor tanks at the hatchery, lugging milk crates stacked with coral from boats anchored at the nearby beach. The coral were first dipped in water laced with iodine to kill any unwanted bacteria and then moved to larger tanks under a shade tarp to be gradually cooled down.
At the disinfecting tent, Joe Unsworth logged identifying data from each tagged coral and organized the loads of staghorn and elkhorn coming to be treated. Because each colony has been bred differently, keeping track of what goes where is vital to the research.
“They're all two species, which may not seem like it's a whole lot of diversity, but we have samples of each of those species from all the way down to Key West and Dry Tortugas,” he said.
To ease their transition and keep from adding to the stress, the corals will be put in tubs where water temperatures are gradually lowered.
“We'll rinse them off in just regular plant seawater and then they're going to go inside one of these big tanks,” he said as he stood amid yellow and black bins that he’d bought at Home Depot that morning. “They're like 20% off now because it's back to school season. So it worked out perfectly.”
The coral will likely stay onshore for at least two months until the bleaching passes, Lirman said..
“All the corals that we brought in thus far were healthy looking, which tells us that we are doing this at the right time,” he said, “The keys were not that lucky because even though they mobilized and they were able to save key genotypes and a lot of biomass by moving them to the north or to land base facilities, they still had really high numbers of bleaching.”
They’re also closely watching corals left in the nurseries to see how they fare during the bleaching. Lirman and UM coral scientist Andrew Baker have been working to breed more heat tolerant coral in the nurseries that Lirman started more than a decade ago. In recent years, he says he’s counted four emergencies — dredging Port Miami, bleaching, stony coral and Hurricane Ian — where he led or assisted in a coral rescue.
“We're still hopeful that we're not going to see the really harsh conditions that they've seen in the lower and middle Keys. We haven't seen bleaching in our nursery. We haven't seen bleaching in our Key Biscayne reefs,” he said. “But everything we hear from Biscayne National Park and south, it's not really good news."
To document the spreading die-off, NOAA is plotting 3D maps to create a baseline of the reef structure, said Enochs, the director of NOAA’s Atlantic Oceanographic and Meteorological Lab’s coral program. They’re also studying closely how this bleaching hits Cheeca Rocks, where NOAA has been monitoring and tracking temperature since 2012, along with other sites in the Keys.
But other than hurrying to rescue coral, he says scientists feel frustrated by how little they can do.
“Quite frankly, it makes some of us, myself included, feel a little bit powerless,” he said. “What we're doing right now is monitoring and watching and seeing who survives and who doesn't. And that's really what we're able to do at scale.”