Off Miami’s coast, a possible solution for threatened coral reef

Rare colony of corals thriving in shipping channel could hold key for genetically modified versions to adapt

Florida officials have tried to speed coral growth by building artificial reefs, many on scuttled ships like this one.
Getty Images

MIAMI — Consider the circumstances of diving 45 feet into a treacherous shipping channel where massive cruise and cargo ships pass on their to way one of the United States’ busiest ports.

“Diving in Government Cut is such an intimidating, dangerous type of dive, with a strong current and high turbidity," said Colin Foord, a co-founder of Coral Morphologic, a multimedia coral laboratory in Miami. “If you’re not holding on to the lock, you’re going to get sucked into the propellers of one these cargo ships.”

Foord is not an extreme diver, but he is an extreme lover of corals.

Several years ago, he discovered a rare colony of corals close to the surface in Government Cut, Miami’s shipping channel connecting the Atlantic Ocean to Biscayne Bay. It was a hybrid of staghorn and elkhorn corals, two federally protected threatened species.

“What’s so interesting is that from my perspective, it’s displaying hybrid vigor, meaning that it’s more resilient and stronger than its parents,” Foord said.

A hybrid staghorn coral (Acropora prolifera) illuminated neon green under fluorescent light at night.
Coral Morphologic

If it’s true that the coral is displaying a type of hybrid toughness, it could pose an exciting clue for understanding how corals become resilient. Once abundant all over the Caribbean and Florida reef tracts, staghorn (Acropora cervicornis) and elkhorn (Acropora palmate) populations have dwindled to the point that they are now listed as threatened on the federal endangered species list.

The decline of these fast-growing branching corals is not to be underestimated. Worldwide, reefs are dying at alarming rates, and scientists estimate the percentage of threatened reefs will increase to more than 90 percent by 2030. Caribbean coral reefs have already eroded significantly because of warming ocean temperatures from increased CO2 in the air and additional stressors, such as diseases and overfishing. The Florida Reef Tract is following the same pattern.

At the shipping channel, Foord and other scientists are waiting for permits to remove the hybrid coral for research.

But the timing couldn’t be worse.

Industrial dredging platforms — machines that rival the Death Star from “Star Wars” for intimidating destruction — will begin pulverizing the floor of the main harbor to a depth of 50 feet to make way for megaships arriving from the newly expanded Panama Canal, scheduled to begin operating by 2015.

In the path of this big dig are some of the healthiest corals around Miami. What has Foord so intrigued is that these corals are thriving in an industrial environment with fluctuating temperatures, salinity changes and pollution. With every incoming tide, water flushes in from the ocean and with every outgoing tide, dirty water from Biscayne Bay goes out. Corals, which are attached to the limestone bottom and granite walls, feed on the nutrients and phytoplankton that pass through.

“It’s ironic that it’s hard to get corals for research subjects, but here the government is destroying so many without recovering them all before the dredge project,” Foord said.

Identifying genes

A diver collects corals from Government Cut.
CSA Ocean Sciences Inc.

The U.S. Army Corps of Engineers has relocated about 355 colonies of nonthreatened corals and 39 colonies of threatened staghorn corals to nearby locations. Even though the process includes the restoration of more than 16 acres of sea-grass beds and the creation of over nine acres of artificial reef, much of the coral growth will be destroyed.

“For the record, we’re not against the dredge project, but the window to remove all these corals may be one or two weeks,” Foord said. “It’s totally insane.”

But if corals seem helpless because they’re rooted in one place, they’re not. The good news is that not all reefs around the world are dying.

Mauricio Rodriguez-Lanetty noticed this and was inspired to investigate different species of coral, which led to groundbreaking research. His team found that some corals had genes that helped them acclimate to stressors like warmer surroundings.

“We have been able to identify those genes that facilitate the process of resistance, the genetic signature associated with tolerance,” said Rodriguez-Lanetty, a biology professor at Florida International University.

This breakthrough is still at the basic research stage, but it could pave the way for gene therapy as a way to manipulate corals so they become more resilient to stressors.

For now, since corals can be cloned from a fragment of their structure, scientists are taking it a step further by selecting genetically diverse pieces with and growing them in offshore nurseries for later replanting. 

A planting frenzy

The Nature Conservancy has teamed with a consortium of entities and is heading up the largest coral restoration project in the world by expanding coral nurseries throughout Florida Reef Tract, plus the Virgin Islands.

“We’ve got six nurseries where were growing coral and a multitude of restoration sites where we plant the coral out to bring back the reef structure,” said Chris Bergh, South Florida conservation director for the Nature Conservancy.

One of those large sites is off the coast of Fort Lauderdale. The Nature Conservancy, the Nova Southeastern University (NSU) Center of Excellence for Coral Reef Ecosystems Research and the National Oceanic and Atmospheric Administration have grown nearly 3,000 colonies of staghorn corals since the project began in 2008.

“These are fast-growing coral, which grow about three to five centimeters a year,” said David Gilliam, an NSU research scientist. “So in a year we have enough material to outplant the larger fragments. This helps the species recover, and they provide habitat, which is very important.”

Farther south, all along the Florida Keys, citizen-scientists are diving and planting thousands of staghorn and elkhorn colonies in the Florida Keys National Marine Sanctuary. The coral may be fast-growing, but officials in Florida have been trying to speed up the process by building artificial reefs.

“In the ’80s and ’90s, there was never enough recreational dive opportunities, so we were building artificial reefs to take pressure off natural reefs,” said Ben Mostkoff, who was the artificial-reef coordinator for the Department of Environmental Resources of Miami-Dade County for two decades.

Artificial reefs are made of durable, stable and environmentally safe materials like steel or concrete and are placed on the ocean bottom to attract floating baby coral, or polyps, to settle and multiply. Now more than 28 artificial reef sites — including nearly 50 large vessels, two retired oil-production platforms and thousands of tons of concrete materials — dot the 35 nautical miles off the coast of Miami.

Stigmatized solution?

Mostkoff holds a patent for a reef-building unit that is made of concrete and rubber chips from tires in the shape of tetrahedron. Despite studies that found that the tetrahedron reef builder was extremely effective and economical, it didn’t catch on.

“It befuddles me,” he said. “Just because you build a better mousetrap doesn’t mean anyone is going to use it.”

Part of the problem is that the rubber had a stigma attached to it, which harkened to the days of an environmental disaster that began with good intentions.

Nearly 2 million scummy rubber tires are tossing around on the ocean floor about two miles off Fort Lauderdale’s coast. In the 1970s, environmentalists and government officials devised a plan to repurpose discarded tires that were piling up in landfills by tossing them in the ocean to serve as a giant artificial reef. But that was before scientists realized coral didn’t grow on rubber. Since then, the metal bindings that held the tires in place have rusted off, and with the ebbs and flow of the currents, the loose tires are crashing into the natural reef.

This summer the Florida Department of Environmental Protection plans to have a contractor remove about 368,000 tires from the area closest to the shore, where the tires pose the most significant threat of damage to the reef. But more than 1 million tires remain, and it’s uncertain if they will ever be removed.

It has been an unusually warm winter in South Florida, and the latest federal study reports that coral reefs may be able to adapt to moderate climate warming. The big question with all these efforts to restore coral reefs is, will it be enough to offset the impact of worldwide stressors that that are decimating coral populations?

“I think these corals in Miami are the most important to study on the planet because most research looks at sick coral in a healthy environment,” Foord said. “We need to understand how this coral is evolving and, by doing so, we can unravel the clues for how corals adapt in today’s modern world that interfaces with man and industry.”

This story has been updated to correct the agency planning to remove rubber tires from the ocean floor this summer.

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