The crescent moon, just a sliver of silver above the palms, is starting to set on a balmy June evening as two dozen volunteers switch on their red-filtered headlamps at a restricted research facility off the windward coast of Oahu.

They stand in the dark around large tanks and buckets of seawater, anxious to start collecting tiny sacks of coral sperm and eggs for scientists at the Hawaii Institute of Marine Biology.

These long summer spawning nights on the 28-acre Moku o Loe, commonly called Coconut Island, are part of a groundbreaking “assisted evolution” experiment that could save coral reefs — and, in turn, humans — from some of the most serious effects of climate change.

“We don’t want to leave it to chance because the risk of doing nothing at this point is so high that it really washes out any of the risks of attempting to intervene,” says Ruth Gates, the institute’s director.

Coral, an animal that has survived on this planet for more than 200 million years, is in dire danger. Some species’ very existence is threatened to the brink of extinction.

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More than 500 million people depend on healthy coral reefs for food. And millions more rely on thriving reefs to drive their tourism-based economies.

Valued in the billions of dollars, if not more, coral reefs protect coastal communities by creating natural sea walls that dramatically diffuse wave energy and storm surges.

They also serve as underwater rainforests, regulating atmospheric gases. They provide medicinal benefits for humans and are home to a quarter of all marine life.

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But in the last 30 years, half of the world’s coral reefs have been lost, scientists say. Unprecedented bleaching — a stress response that leaves corals vulnerable to massive die-offs — has devastated reefs from Hawaii to Florida, Australia to Africa.

Several corals found in Hawaii are considered “near threatened” by the International Union for the Conservation of Nature. Most are deemed “vulnerable,” and one is critically endangered.

In 2014, the National Oceanic and Atmospheric Administration added 20 new corals to its list of those protected under the Endangered Species Act. It considered nine species in Hawaii but chose not to include them — yet.

The future looks bleak, even if global warming is limited to the 1.5 degrees Celsius (2.7 degrees Fahrenheit) above the pre-industrial levels target that almost every country in the world signed onto in 2015 under the Paris climate accord.

“It’s a very urgent time for reefs,” Gates says. “We’re talking about conditions that will not allow corals to survive in their natural state.”

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The Catastrophe Of Bleaching

A warmer planet increases the frequency of bleaching events, which reduces the time corals have to recover from the previous bleaching and ups the chance they will die.

The Aloha State experienced its first documented back-to-back bleaching event in 2014 and 2015, the worst seen in the Main Hawaiian Islands, according to NOAA.

It overlapped with the third-ever global bleaching event, which began in 2015 and continued into 2016 amid record ocean temperatures across Hawaii and warmer waters in the Caribbean and elsewhere as predicted.

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“The reason this is so troubling, quite frankly, is that our temperatures are now on a trajectory, depending on the warming scenarios, to put us into annual bleaching by 2050,” Gates says.

Scientists have pivoted as a result. Many spent the early part of their careers studying the marvels of corals and sharing their findings in academic papers that rarely went beyond their inner circles. Species were often studied more from a point of fascination than food and land security or economic dependency.

Now these scientists are racing against time. They are leading research efforts to more precisely identify what is killing corals and to help them recover faster and become more resilient to a changing planet.

“The scientific community has come together and decided we have to do better than documenting the demise of reefs,” says Bob Richmond, who heads the Kewalo Marine Laboratory in Honolulu. “We’ve got to come up with solutions to not only understand what the problems are but how to address these problems.”

Hollie Putnam/HIMB

Last year, more than 2,000 coral reef scientists, policymakers and managers from 70 nations rallied in Honolulu to take on that challenge. They met and shared information over the course of a week during the International Coral Reef Symposium, a quadrennial event that was held in Hawaii for the first time.

Richmond, who convened the conference, is the former president of the International Society for Reef Studies, the largest coral reef society in the world. Gates now serves as its president.

He is working with biologists at the Kewalo lab on ways to pinpoint, at the molecular level, what is killing coral, so new management strategies can be developed.

“Some of the work we do is best described as ‘Doctor Dolittle’ meets ‘CSI,’” says Richmond.

“We’re using some modern forensic techniques that we basically mooched from human medicine to be able to understand corals and coral reefs at a much better level than ever before.”

Using the same tool used for analyzing human blood and urine samples, researchers are checking for elevated or reduced levels of specific proteins that can point to specific causes of stress, including whether coral has been exposed to oil or pesticides, he says.

The Birth — And Death — Of A Coral Reef

An individual coral is really thousands of units called polyps. Each is connected to the polyp next door by a bridge of tissue, and each polyp comprises a ring of tentacles that surrounds a mouth. The mouth is on top of a stomach.

A coral reef is a “party of corals,” as Gates puts it, with all different shapes, colors and sizes assembling as a community to create a structure.

“They’re magical places,” she says, noting that the Great Barrier Reef in Australia can be seen from space.

“That is a really remarkable biological innovation,” Gates says. “If you can imagine these tiny, ancient creatures creating these massive cathedral-like structures, it’s really amazing.”

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Corals get their color from a symbiotic algae that lives inside them, usually a dark brown or green.

These tiny plant cells, called dinoflagellates, live inside the animal’s tissues. There can be a million plant cells per centimeter of coral tissue.

But the corals and their internal algae are doing more than just helping each other survive. They’re also sucking down carbon dioxide from the atmosphere — reducing the severity of climate-change effects — and generating oxygen.

“That point is something people forget,” Gates says. “Coral reefs are all just part of the natural world and humans are also just part of the natural world. We’re not unique in being superior or inferior.”

Bleaching occurs when corals are stressed by too-warm or too-cool waters, a more acidic ocean or local factors like sediment and polluted runoff, which happens when heavy rains flush pesticides from fields and oils from parking lots into the ocean.

The corals expel the algae living inside them as a result, leaving their bony skeletons a translucent white.

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In 2015, more than 75 percent of the corals in Kaneohe Bay off the windward shore of Oahu bleached when warmer waters passed through. As the cooler waters returned, the corals started to recover but many did not reproduce the next year.

When back-to-back bleaching events occur, it often spells death.

If the planet warms 1.5 degrees Celsius, as prescribed under the Paris climate agreement, the likelihood of annual bleaching is still 50 percent, scientists say.

At 2 degrees, that likelihood soars to over 75 percent.

This summer, Hawaii’s waters have been hovering just under the bleaching threshold of 28 degrees Celsius (82 degrees Fahrenheit), according to NOAA’s bleaching heat stress gauges.

But the outlook for this fall is not good. NOAA has Hawaii under an Alert Level 1, which means significant bleaching is expected within a few weeks. That’s only one step below its highest alert, which is reserved for cases in which widespread bleaching and significant coral mortality are likely.

Time Is Running Out

It’s this sense of urgency that has Gates and others working on experiments to breed “super corals” that are more resilient to warmer, more acidic waters.

Gates says there are three fundamentally important aspects that drive whether a coral will bleach or not — their parents, their partners and their past.

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A coral’s partner affects how they respond to stress. Some are more tolerant to temperature change, for instance, and some feed better.

If the corals have been exposed to conditions that challenge them, they may be more likely to be able to cope with more challenging conditions in the future.

“It’s the what-doesn’t-kill-you-makes-you-stronger feature,” Gates notes.

“When we talk about this loss of coral — that 50 percent have already died — what we’re really saying is the rates of change in the environment are outpacing the capacity of the system to adapt to them,” she says. “It’s really a very simple thing.”

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That’s why she and other scientists are testing “assisted evolution” and “assisted migration” theories.

The studies involve selectively breeding corals that survived recent bleaching events to create a “super coral.” Tests are also being conducted to see if those corals live better in the places they came from or if they can thrive in other areas.

“If we know genetics are important, why wouldn’t we selectively breed the strongest corals on the reef to create offspring that we know would have a better chance of surviving than offspring that have been generated from the random union?” Gates says.

“And if we know the partnerships are critically important,” she says, “why wouldn’t we take the chance out of that and direct those partnerships to optimize the performance? And if we know that the environmental history is important, why not challenge them artificially, train them in environmental treadmills?

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Gates and Madeleine van Oppen from the Australian Institute of Marine Science won the Paul G. Allen Ocean Challenge in 2013, which came with a $10,000 prize. Gates says it let them apply for a grant that brought them $4 million to underwrite a five-year project, which they began about 18 months ago.

She calls the money from the foundation, created by Microsoft co-founder Paul Allen, “transformative” for the project.

The Hawaii Institute of Marine Biology — which, like Kewalo Marine Laboratory, is connected to the University of Hawaii — has also been given expensive equipment that helps with the research.

In 2011, philanthropist Pam Omidyar donated a laser-scanning microscope that can elevate water temperature and acidity while viewing the specimen. It’s one of just a few like it in the country, and is made even more unique by being in a lab that’s adjacent to a coral reef ecosystem.

“If you’re a science nerd, this is the Holy Grail,” says Ariana Huffmyer, who’s working on her doctorate at the lab.

The Sex Life Of Coral

CORAL SPAWNING from Honolulu Civil Beat Inc on Vimeo.

It’s dark when two dozen scientists and their helpers arrive on Coconut Island, famous as the opening shot in the long-running 1960s sitcom “Gilligan’s Island.”

The volunteers include students from the University of Hawaii, visitors from California, graduate students from Colorado, state planners, visiting professors of biology and others.

They gather, elbow to elbow, around several large tanks filled with seawater and coral heads that were recently taken from Kaneohe Bay. Their headlamps, covered with red filters to not trick the corals into thinking it’s daylight, reflect off the water, giving the event a surrealistic vibe and prompting one grad student to term it “a red-light district.”

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“My humps, my humps… my lovely coral bumps,” another volunteer sings to the tune of The Black Eyed Peas’ “My Humps.”

Corals reproduce only one or two nights a year and only during the summer. The group is eagerly awaiting the spawning on this Sunday night in June.

“You can time your watch by when they will release their eggs and sperm depending on the species,” Gates says. “But they all do it at night which makes it a nightmare to do.”

Just before 9 p.m. the spawning begins.

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Suddenly, hundreds of tiny globs begin to emerge from the coral heads and float slowly to the surface, like a lava lamp broken apart, the red-filtered headlamps lighting their upward paths.

The miniscule “bundles” of sperm and eggs — some of the coral are male, some female and some even hermaphroditic — gather at the surface. Volunteers carefully suck them up with pipettes and squirt them into vials.

“They look like pink Dippin’ Dots,” says Beth Lenz, who is pursuing her doctorate in marine biology at the University of Hawaii.

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Breeding A ‘Super Coral’

Earlier that afternoon, Kira Hughes, project manager at Gates’ lab, steers a small boat across Kaneohe Bay to check on the “coral condoms.”

Fine mesh nets are attached around the base of corals that survived the last bleaching event. They are buoyed by floats to remain vertical in the water, which lets the bundles of eggs and sperm float up to the surface where scientists collect it.

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Hughes dives down a dozen feet to ensure the nets are still securely fastened and makes a couple minor adjustments.

Then, with a few flips of her fins, she cruises over to an underwater lab of young corals that are growing in the bay. It’s patient work, as Hawaii’s corals generally only grow about a centimeter a year.

Hughes is working with other scientists to collect as much spawn as possible and breed these super corals while making them even stronger.

Protecting Vulnerable Creatures From Disease

On the other side of Oahu, at the Kewalo Marine Laboratory, Richmond is contemplating the Irish Potato Famine of the mid-1800s. More than a million people died and a million more were forced to leave Ireland when a fungus wiped out the potato crop vital for much of the country’s subsistence.

The Irish had chosen one genetic variant of potato that did really well under the harsh conditions there, but they got rid of all the other types in the process, which made virtually all the potatoes susceptible to a single pathogen.

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While Gates is looking for certain genetic variants that do well with temperatures rising, which is critical for climate change, Richmond wants to ensure corals are also protected from the next disease or pesticide.

“When we start losing genetic variants, that’s the scary part about setting yourself up for one morning waking up and everything’s gone and you didn’t see it coming,” he says.

Richmond is looking at the hardy corals of Honolulu Harbor for answers.

“No self-respecting coral should live in Honolulu Harbor yet we have these thriving populations of corals,” he says, referring to the harbor as a “nasty place” full of chemicals and toxicants.

Kewalo Marine Laboratory Director Robert Richmond PH.D. from Honolulu Civil Beat Inc on Vimeo

He suspects certain genetic variants are making this possible. He says scientists have long been able to identify different species but now need to identify the many different genetic variants and determine if some are disappearing.

Ten miles up the coast, corals in the nearshore waters of Maunalua Bay have adapted to sedimentation and polluted runoff. Many are healthy and strong and Kaho Tisthammer, a post-doc researcher at the lab, grabs a few of these seemingly resilient corals and moves them farther out in the bay.

While she’s out there, she plucks some of the same species and brings them closer to shore. But those corals, it turns out, can’t take the nearshore conditions — they’ve not adapted to the harsher environment like their relatives have, a critical genetic variation.

Now, Tisthammer and her colleagues want to know what’s happening to these corals while it’s happening — not wait for them to die to try to figure it out. She points to what looks like a really intricate New York City subway map that shows coral proteins and how they interact with their environment. They hope to develop a quick diagnostic test to better monitor coral health.

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‘Ethical Dilemma’

While scientists generally agree on the problems facing coral reefs they aren’t necessarily on the same page when it comes to how to save the corals.

Should coral reefs be returned to their most natural state and defended against the elements that threaten their existence?

Some researchers say the time has passed for that approach to be effective, or even feasible. They want what limited funding they have to be directed at maintaining the coral reefs that provide the most value, whether that’s food security or economic dependency.

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“This is where we’re at,” Gates says. “The ethical dilemma that I think scares me most … is the paralysis associated with different perspectives and the potential void you can drop into.”

More and more, she finds herself somewhere in the middle.

“I’m really pragmatic about where we are; it’s not good,” she says. “I’m also very aware of the fact that we have very little time to settle the debate.”

The risk of doing nothing is too high.

“When you start talking about what it means … to humans if we don’t have reefs, it’s such a devastatingly bad news story,” she says. “We’re talking about not having enough food for people. We’re talking about not having enough land to live on.”

Watch a slideshow of corals and the scientists who love them, below: