Inside a nondescript warehouse in Orlando, Fla., filled with 300-gallon aquariums, a sophisticated LED lighting system is set on a timer to mimic the sun and moon cycle of Key West, some 300 miles away.

This space, which has been described as a Noah's Ark for coral, is a key part of the strategy to help the survival of the only barrier reef in the continental U.S.

The reef is one of the country's most endangered environmental jewels. It is the third-largest barrier reef in the world and stretches more than 350 miles off the Florida coast from the city of Stuart to Dry Tortugas National Park. It's a diverse ecosystem, a tourist attraction and it helps protect the coast from storm surges, providing billions of dollars in economic benefit.

Over the last half-century, the reefs have lost 95% of the coral that once covered them because of development, human activity and climate change. The loss of corals — tiny, ancient marine animals — has spurred scientists, activists and government officials to form a plan for their long-term survival.

A Noah's Ark for coral

Hundreds of corals from 18 different species were collected in the Florida Keys and brought here, to the Florida Coral Rescue Center, for safekeeping. With near-perfect conditions, the corals have thrived and begun to reproduce.

Most corals spawn at night several days after a "full moon" mimicked by the lighting system.

When that happens, Justin Zimmerman, a supervisor here, says his staff pulls all-nighters, watching the corals. "Their eggs and sperm are buoyant, so they float to the top," he says. "We can collect those, let them fertilize and then will settle the baby corals, the larvae after they develop, on little tiles."

The baby corals increase the genetic diversity of species that are facing myriad threats to their long-term survival. That's why three years ago, SeaWorld, in partnership with Disney and the Fish and Wildlife Foundation of Florida, opened this facility.

A multitude of threats

The most recent threat to the reef has been stony coral tissue loss disease, says Andy Bruckner, a researcher with the Florida Keys National Marine Sanctuary. "That probably killed more coral in Florida than any other single event has," he says. "It affects these big boulder corals that grow much more slowly and that are more important in terms of building the framework — the structure — these other corals live on."

There is some hope now that the disease has peaked and may subside. But the damage it's done is substantial, adding to the devastation that's left many vibrant, colorful reefs now largely gray and lifeless.

Scientists and divers agree — Florida's coral reefs have declined dramatically since the 1960s and '70s. Bruckner says there's no single smoking gun responsible for the devastation. There are local stresses, like damage done to reefs by boat anchors or irresponsible divers and fishermen. There are regional issues, including poor water quality and overfishing. "And the global stressor," he says, referring to climate change. "That's probably the No. 1 factor that's affecting reefs," he says, and ultimately could be responsible for their demise if we don't take steps to address it.

The warming oceans cause thermal stress, leading to bleaching events and making corals more susceptible to disease. Another concern is ocean acidification from the growing amount of carbon dioxide absorbed from the atmosphere.

Critical action

The sharp decline of Florida's barrier reef and the growing threats to its long-term survival have mobilized a broad coalition of activists, scientists and government officials.

"These are the only reefs like it we have in the continental United States," says Sarah Fangman, the superintendent of the Florida Keys National Marine Sanctuary, which includes nearly all of Florida's reefs. "We don't have a spare Florida reef system. So, we must do something."

For the past three years, the National Oceanic and Atmospheric Administration has been spearheading a project to restore several of the best-known coral reefs in the Florida Keys. Known as Mission: Iconic Reefs, it's an effort that involves environmental groups, research institutions and government agencies. Now, Fangman is pushing for the adoption of a new set of regulations, a "Restoration Blueprint" to expand protections for the reefs.

The measures are critical she says, but she's a realist. No matter what steps are taken, it won't be possible now to restore the reefs to the way they used to be. "Those conditions no longer exist," she says. "So, what we need to do is to give our corals a chance in current conditions to thrive and be resilient."

A sense of optimism

Among those closely involved in restoring the coral reefs, there's an almost surprising sense of optimism. Since 2007, a group based in the Florida Keys, the Coral Restoration Foundation, has been working to show it's possible to restore declining reefs and bring them back to vitality. The group has pioneered the use of underwater offshore nurseries where it grows coral. When they're large enough, the new corals are transplanted onto established reefs. So far, more than 200,000 corals have been planted.

In Key Largo, Mary Doerr was one of several volunteer divers who recently returned from a day transplanting elkhorn corals onto an ailing reef. Doerr, a self-described marine biology nerd, says it was great to see the new growth of newly transplanted coral, but the reef is far from healthy. "It definitely doesn't have the richness and diversity of fish," she says, "and it doesn't have sort of the complex branching structures and the real depth of character and structure that a healthy reef has."

The Coral Restoration Foundation's CEO, Scott Winters, says working with other groups, his staff developed a construction plan to rebuild the endangered reefs, beginning with one of the best-known, Carysfort Reef. Winters says there's now more coral on Carysfort than any other time in the last 15 years. "Almost everything you see on Carysfort Reef now is a direct result of our activity to put corals back out there," he says. "And more importantly, they're thriving and sexually reproducing."

Winters says the goal is to bring back the coral populations to a level where they can once again begin rebuilding the reefs on their own. Scientists hope that if they keep reefs healthy and thriving, corals will develop the genetic diversity that may help them continue to grow and to adapt to long-term threats, including climate change.