On a recent breezy evening on an island off the coast of Oahu, a team of scientists gathered around an outdoor wooden table and peered down at row after row of mushroom coral.

Surrounded by test tubes, a variety of marine specimens and a nearby pool of hammerhead and reef sharks, the group was intently watching for an unusual event that could help save one of the most threatened species on the planet.

Mary Hagedorn, a scientist with the Smithsonian Institute, and her colleagues (including two high-school students on assignment) were waiting for sperm — coral sperm. They were hoping that at any moment, as the sun dipped below the horizon, the coral would erupt, sending dozens of eggs and sperm into the water.

Hagedorn’s remedy for the world’s disappearing coral? Create sperm banks.

The scientist, with a Ph.D. in marine biology from Scripps Institution of Oceanography, has been working on just that for the past eight years, using a 28-acre parcel off of Kaneohe Bay made famous in the opening credits of the 1960s sitcom Gilligan’s Island as her lab.

Coconut Island was once home to the heir of the Fleishman yeast fortune who imported hundreds of exotic plants and animals and constructed a pool with a diving board and slide. It also served as a rest and relaxation retreat for U.S. naval officers in the 1940s. But Coconut Island is now owned by the state and is the site of numerous experiments being conducted by scientists at the Hawaii Institute of Biology.

One of those is Hagedorn’s scientific venture to save the world’s coral reefs by essentially preserving them in storage. The specimens she collects could be used to diversify reefs that are suffering from disease and bleaching in the near term, and allow scientists to bring back extinct coral species in the decades — or centuries – to come.

But on this night, Hagedorn’s team would have no such luck. The animals were probably too cold, she said. The warm, muggy air off Oahu’s windward coast was tinged with a chilly breeze.

The three-evening vigil was at its end. Hagedorn would have to wait until next month — two days after the full moon — for a new coral spawn.

Despite the evening’s disappointment, Hagedorn’s work has been remarkably successful. She’s preserved six coral species in total — two each from Hawaii, the Caribbean and Australia. In the past four years, she’s frozen 1 trillion sperm cells and 3 billion larval cells, as well as embryos and stem cells.

Once coral does spawn, Hagedorn and her assistants work quickly to capture the sperm and eggs and freeze them. It’s an exercise that Hagedorn has repeated dozens of times.

While collaborating with nearly a hundred scientists throughout the world, in places like the Caribbean, Belize and Australia, she is working to improve the technology and train others in how to use it.

“It’s really for the future,” said Hagedorn, who speaks passionately about her experiments. “I’m never going to see the outcome of my work really. It might be used in the next 10 years to diversify populations. But the bulk of what we do is training people, getting banks built in other countries by other scientists. And hopefully those banks will be used hundreds of years from now to repopulate reefs.”

High Stakes

The world’s coral reefs support 25 percent of the species in the ocean at some point in time, said Hagedorn.

“And if 25 percent of that would be eliminated, we have no idea what the consequences would be on the remaining things in the ocean,” she said.

But Hagedorn was blunt when it came to potential human impacts.

“If coral reefs were to become imperiled, fish would become a luxury item and hunger would increase around the world,” she said.

Hagedorn’s alarm about the destruction of coral is being echoed by hundreds of scientists.

Thirty to 40 percent of the world’s reefs have been heavily impacted by human activities and another 30 percent are at great risk, according to Robert Richmond, president of the International Society for Reef Studies and a University of Hawaii professor. Richmond was speaking from Queensland, Australia where about 2,700 of the world’s scientists have convened this week for a conference on coral reefs.

The scientists have issued a statement calling on all governments to take global action to reduce carbon dioxide and greenhouse gas emissions and protect local reefs from pollution, sedimentation and overfishing.

Globally, if something isn’t done to reverse the human impacts on coral reefs, Richmond said, the results will be severe.

“Basically, our projections are that by the end of 2100, by the end of this century, the coral reefs will be a mere shadow of what they used to be,” he said.

Currently, Hawaii’s reefs range from completely degraded to being in good shape, said Richmond. But without a change in human behavior, their future isn’t certain.

The reefs in the main Hawaiian islands are suffering from severe overfishing, land-based pollution including sedimentation and sewage spills, and injection wells that are leaching excess nutrients into the nearshore environment, according to Greta Aeby, a coral specialist at Hawaii’s Institute of Marine Biology.

Challenges Remain

Hagedorn has proven that cryopreservation of coral sperm works. But it’s not all that simple.

She has successfully grown new coral for up to six months in captivity. The next step is to make sure it works in the wild and that the coral can survive for five to eight years, the point at which they reach maturity and begin to spawn.

The coral, brought back to life years from now, also might not be able to survive in marine conditions if they continue to degrade.

Warming waters are causing coral bleaching throughout the world, a process by which coral expels critical algae living in its tissues, turning it white. Without remedy, it can kill the coral.

Currently, the ocean’s surface has warmed by .7 degrees celsius, “resulting in unprecedented bleaching and coral events,” according to scientists at this year’s coral reef symposium. At the current rate of carbon dioxide emissions, the scientists are projecting that by the end of the century surface waters will have risen by 2 to 3 degrees celsius, the sea-level will have risen by as much as 1.7 meters, the ocean’s pH balance will decrease and storms will increase in frequency and intensity.

“The combined change in temperature and ocean chemistry has not occurred since the last reef crisis 55 million years ago,” they say in a consensus statement issued this week.

If things aren’t reversed, Hagedorn conceded that the coral being preserved today won’t be able to survive future conditions.

She believes the “horse was out of the barn” when it comes to global warming. But other impacts to reefs, such as runoff, overfishing and pollution, can still be controlled. And the technology buys time for changing course or developing cutting-edge solutions for protecting the world’s reefs — even if it takes better engineering, said Hagedorn.

“The good thing about the technology is that they can live 150 years in the bank,” she said. “And so this really is a process that gives us that ability to figure out the policy, education and conservation tools that we need to maintain our ecosystems in optimal health.”

The technology may also have immediate impacts for the coral reefs in Kaneohe Bay which have suffered two recent outbreaks of a disease called Montipora White Syndrome.

Hagedorn’s work “provides an insurance policy so if we do continue to lose corals, her sperm banks provide a means to maintain genetic diversity which is very important for species survival through time,” said Aeby, who has been studying the disease.

She said that the incidence of disease is likely to only get worse in Hawaii if conditions don’t improve.

“Unfortunately, these outbreaks are starting to occur just as they did in the Florida Keys in the 1970s and 1980s,” she wrote by email. “Their once dominant corals are now on the endangered species list. If the people of Hawaii do not make the decision to protect the reefs from these multitudes of stressors then Hawaii’s reefs will likely decline as the Florida Keys reefs did.”

Declining marine conditions can lead to sick coral, says Hagedorn.

“Humans often get diseases when they are stressed. You get run down when you are taking your exams. You get a cold, whatever. It’s true for the coral as well,” said Hagedorn. “They are under such stress all the time from local and global stressors. I think many of the diseases are probably in the water already. They are just picking them up now because they are stressed.”

A Depressing Last Resort?

Scientists have warned about the need to reverse global warming for decades, but emissions of carbon dioxide and other greenhouse gases have continued to rise. More recently, countries and states, including Hawaii, are talking more about how to mitigate the impacts, than reverse them.

On Monday, Gov. Neil Abercrombie signed legislation putting into place a statewide climate change “adaptation policy” aimed at dealing with the effects of global warming.

And the turn toward sperm banks may seem like a last ditch effort to save coral from the inevitable impacts of global warming.

Richmond said that Hagedorn was doing fascinating and important work, but that resorting to freezing sperm and eggs isn’t the most uplifting vision for the future.

“If we ever get to the point that we have to depend solely on what is left in the freezers, we are going to be in dire straits,” he said. “But I think it is very important for some species. It might be the only chance they have.”

Hagedorn has struggled with attracting funding for her research and says she has spent thousands of dollars of her own money to support the work. She says that maybe “it’s an idea out of time,” but the time to act is now.