The Death and Life of Coral Reefs

In South Florida and around the world, coral reefs are in trouble. But scientists are leading the fightback – and in some cases, divers can help.


Ashley Harrell

Published date: 

Jul. 1, 2016

richard-m-bassett-rescue-a-reef-2.jpgTwenty feet below the surface of Biscayne Bay, outfitted in scuba gear and equipped with a bunch of tools from Home Depot, I am attempting to hammer a nail into the rocky ocean floor. I’m one of around 50 divers doing this as part of Rescue a Reef, a University of Miami citizen scientist program that aims to rebuild this undersea ecosystem, one coral at a time.

The plan is to hammer in the nail and then zip-tie it to a fragment of threatened staghorn coral, tightly securing the coral and ensuring it contacts the substrate. Because the coral grows fast, regenerating like a starfish, this finger-sized fragment will soon mushroom around the nail and zip-tie, and in a year it should be the size of a basketball. But first I have to get the nail in. 

I exhale, decreasing my buoyancy and descending on the reef, taking care not to disturb or crush any nearby corals, sea fans or other plant life. I clear a patch of rock with a wire toothbrush, scattering sediment and algae and mucking up the visibility. I hold out a nail and do a practice swing, but before I can strike, the current drags me up and away like some inept astronaut. I swim down, quickly line up my hammer and bash the nail, hoping it sinks into the rock. Instead it bends and is rendered useless. I grab another nail and hit that one cockeyed, sending it flying.

I am learning that it is very difficult – though not impossible – to help coral reefs. This is unfortunate, considering how desperately they need it. 

Unless you’ve been living under a brain coral, you’ve probably heard the news about the world’s most magnificent reefs being in decline. Recent studies and headlines have informed us that 93 percent of the Great Barrier Reef’s corals are suffering, primarily from coral bleaching. This happens when extreme temperatures or weather cause the corals to expel the algae living inside them. In the Coral Triangle – the world’s most diverse reefs that lie off Southeast Asia – reports found that 85 percent of the coral is threatened by overfishing, pollution and coastal development. Disease and rising ocean temperatures are devastating the reefs of the Caribbean, with experts predicting that in 20 years, they will be gone.

South Florida’s barrier reefs – the only ones in the continental United States – aren’t faring so well, either. In what experts are calling an unprecedented die-off, bleaching, disease and dredging projects have damaged untold stretches of reef from the Florida Keys up to Martin County. The latest threat that studies have detected is acidification, which occurs when the ocean absorbs carbon dioxide (a result of global warming) and becomes more acidic. This blocks corals from absorbing calcium carbonate, which is necessary to prevent their skeletons from dissolving.

“We are now seeing emergency-level crisis events on these reefs every year,” says Rachel Silverstein, executive director and waterkeeper of the ocean advocacy nonprofit Miami Waterkeeper. “We thought we had decades to fix these problems, and it turns out we don’t.”

Losing the reefs would be devastating to South Florida, where tourism and fishing industries bring in about $7.6 billion annually and employ around 70,000 people, according to a report by University of Miami marine biologists. The reefs also protect the shore from flooding and erosion.

Despite these concerns, a completed dredging project in PortMiami and a similar project proposed for Port Everglades are contributing to the problem, scientists say. Its plan called for minimal damage, but the Army Corps of Engineers buried 81 percent of the coral near PortMiami in sediment, according to a report from the National Oceanic and Atmospheric Administration (NOAA). Despite the disaster, the Corps has not changed its approach for its next dredging project in Port Everglades, Silverstein says. richard-m-bassett-rescue-a-reef-19.jpg
Miami Waterkeeper sued the Corps over the PortMiami damage, forcing it to pay $400,000 to relocate a few hundred staghorn corals from the dredging site to a University of Miami nursery. I visited that nursery the first dive of the day with Rescue a Reef. 

The prognosis for South Florida’s reefs – while mostly dim – has a few bright spots. In the last year, large patches of staghorn coral have been discovered off Fort Lauderdale’s coast, offering hope that under specific conditions, the threatened species can thrive. Nova Southeastern University research scientist Brian Walker and his lab have just begun a study on the characteristics of those patches, which can be applied to restoration efforts.

“No one understood why these dense patches were there, but they seemed to be doing well,” Walker says. “During our mapping, we found 35 new ones over an estimated area to up to 150,000 square meters, or about 37 acres. That’s an extensive area.” Over at the University of Miami, the chair of the department of marine biology and ecology Chris Langdon is researching what types of coral might flourish despite changing ocean conditions. He likens his research to “putting corals on treadmills,” varying the conditions of their environments to ascertain which genotypes are the most robust. 

Langdon’s colleague at the University of Miami, scientist Diego Lirman, is working on the same problem from a different angle. He’s the head honcho for Rescue a Reef, the unique restoration program that gets citizens into the water for some hands-on restoration. It was the one-year anniversary event for that program that I dropped in on.

The day starts at 8 a.m. at Diver’s Paradise, a dive shop adjacent to the Crandon Park Marina on Key Biscayne, where about 50 citizen scientists gather to help transplant coral from the nursery to a struggling reef. “When you go on a dive, they say, don’t touch the corals because you can kill them,” says Lirman, who with a bit of sunscreen in one eyebrow looked the part of the absent-minded scientist. “That’s true. But this is a special trip where you’re going to touch the corals.”

About 15 feet down, 10 trees are anchored to the ocean floor in this nursery, one of three that the researchers created and maintain. Each tree has fragments of staghorn coral, a threatened species with a crucial role in building reef systems, dangling from string like so many leaves.

Our group leader, researcher Stephanie Schopmeyer, demonstrates how to use the wire brushes to clear the PVC pipes and monofilament of algae, crustaceans, and anything else that could inhibit the growth of the coral. It’s a fairly engrossing task, with a tendency to result in trees drifting toward divers, occasionally tangling them. “Don’t freak out,” Lirman advises about this. “Just push the tree away.”
As we clean, a few bewildered-looking blenny fish drift past, perhaps unaccustomed to seeing humans at work underwater. It’s much different than a usual dive, in that you have a task and there is a sense of urgency. If you don’t work quickly, you’ll have to surface and leave the job unfinished.  

Once the pipes are clean, Schopmeyer shows how to snip pieces of coral with crimps. Each of the divers collects five and places them in a net, which we bring to the next dive site. This is where the project gets even more challenging.

Back at the scene of my clumsy hammering, I decide to take a break and look around. I can see numerous staghorn corals; some are wild but most have been planted through the program. What’s clear is that this is a place where staghorn can do well. I admire the purple sea fans swaying gently in the current, as well as the occasional clusters of star and brain corals. Damselfish, surgeonfish and wrasses abound, as do the formidable fire worms, which eat the coral and sting people. Best to avoid these.

Underwater gardening is much harder than regular gardening, I conclude. But I’m determined to do a better job, so I follow Schopmeyer around like a guppy as she hammers nail after nail. With each attempt, I grow more competent with the zip-ties. The secret is to pull them as tight as possible, and it’s OK if you crunch a few polyps. Finally getting the corals tightly secured builds my confidence, and I take back the hammer. I find a suitable area of rock, tap a nail into it, and tie one fragment of coral to the reef, all on my own.

Back on land, I speak with some divers about their own experiences, and Leti Pallozzi, an aspiring divemaster, sums it up pretty well. “In the big picture, I’m not sure what kind of difference I made,” she says, “but I took my grain of sand and contributed something positive. If everyone got involved, we’d have a longer-term impact.”


HEALTHY CORAL Coral and algae depend on each other to survive.

Corals have a symbiotic relationship with microscopic algae called zooxanthellae that live in their tissues. These algae are the coral’s primary food source and give them their color.

STRESSED CORAL If stressed, algae leaves the coral.

When the symbiotic relationship becomes stressed due to increased ocean temperature or pollution, the algae leave the coral’s tissue.


Without the algae, the coral loses its major source of food, turns white or very pale, and is more susceptible to disease.

Corals have a symbiotic relationship with microscopic algae called zooxanthellae that live in their tissues. These algae are the coral’s primary food source and give them their color. When the symbiotic relationship becomes stressed due to increased ocean temperature or pollution, the algae leave the coral’s tissue. Without the algae, the coral loses its major source of food, turns white or very pale, and is more susceptible to disease.

Coral restoration projects like Rescue a Reef happen up and down South Florida’s coast. In June, one such occasion called Coralpalooza took place right off Pompano Beach. Visit the website of the Coral Restoration Foundation,, to find out what events are coming up near you.