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Like Ruth Gates, Charles Darwin was confounded by coral. His first encounter with a reef was in 1835. He was sailing on the Beagle from the Galápagos to Tahiti when, from the ship’s deck, he spied “curious rings of coral land” sticking out of the open sea—what today would be called atolls. Darwin knew that corals were animals and that reefs were their handiwork. Still, the formations baffled him. “These low hollow coral islands bear no proportion to the vast ocean out of which they abruptly rise,” he wrote. How, he wondered, was such an arrangement possible?
Darwin cogitated for years on this mystery, which became the subject of his first major scientific work, The Structure and Distribution of Coral Reefs. The explanation he came up with—controversial at the time, but now understood to be correct—is that at the center of every atoll lay an extinct volcano. Corals had attached themselves to the volcano’s flanks, and as the volcano expired and slowly sank away, the reef had kept growing upward, toward the light. An atoll, Darwin observed, was a kind of a monument to a lost island, “raised by myriads of tiny architects.”
The same month that Darwin published his monograph on reefs—May 1842—he sketched out for the first time his revolutionary ideas about evolution, or “transmutation,” as the phenomenon was referred to in his day. The sketch was written in pencil and, in the words of one of his biographers, amounted to “thirty-five folio pages of crabbed, elliptical scrawl.” Darwin stuck the essay in a drawer. In 1844, he expanded it to two hundred and thirty pages, only once again to hide the manuscript away. There were all sorts of reasons for his reluctance to go public with his ideas, one of which was an almost total lack of evidence.
Darwin was convinced that evolution was unobservable. The process occurred too gradually to be perceived over the course of one human lifetime, or even several. “We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages,” he would eventually write. So how could he prove his theory?
The solution he lit upon was pigeons. In Victorian England, fancy pigeons were a big deal. (Queen Victoria herself kept fancy pigeons.) There were fancy-pigeon clubs, fancy-pigeon shows, and fancy-pigeon poems. “Beneath this laurel’s friendly pitying shade/The patriarch of the cote to rest is laid,” began an ode to a favorite bird, dead at age twelve. Fanciers fancied dozens of varieties, including: fantails, which, as the name suggests, have extravagant, fan-shaped tail-feather arrangements; tumblers, which, in flight, perform backflips; Nuns, which look like they’re wearing ruffs; Barbs, which have a sort of wattle around their eyes; and pouters, which, when they inflate their crops, appear to have swallowed balloons.
A pouter inflating its crop
Darwin set up an aviary in his backyard and used his birds to perform all sorts of experimental crosses—Nuns with tumblers, for example, and Barbs with fantails. He boiled down the birds’ carcasses to get at their skeletons—a task, he reported, that made him “retch awfully.” When he finally decided to publish On the Origin of Species, in 1859, pigeons strutted across its pages.
“I have kept every breed which I could purchase or obtain,” he reports in the opening chapter. “I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs.”
To Darwin, Nuns and fantails and tumblers and Barbs provided crucial, albeit indirect, support for transmutation. Simply by choosing which birds could reproduce, pigeon breeders had developed lineages that barely resembled one another. “If feeble man can do [so] much by his powers of artificial selection,” there was, Darwin speculated, “no limit to the amount of change” that could be effected by “nature’s power of selection.”
A century and a half after On the Origin of Species, Darwin’s argument-by-analogy is still compelling, though every year it gets harder to keep the terms straight. “Feeble man” is changing the climate, and this is exerting strong selective pressure. So are myriad other forms of “global change”: deforestation, habitat fragmentation, introduced predators, introduced pathogens, light pollution, air pollution, water pollution, herbicides, insecticides, and rodenticides. What do you call natural selection after The End of Nature?
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Madeleine van Oppen met Ruth Gates at a conference in Mexico in 2005. Van Oppen is Dutch, but at that point she’d been living for almost a decade in Australia. The women were temperamentally opposites—Van Oppen is as reserved as Gates was outgoing; nevertheless, they hit it off immediately. Van Oppen, too, had begun her scientific career as new molecular tools were becoming available, and she, too, had quickly recognized their power. The two began to speak regularly across the time zones and teamed up to write a few papers. Then, in 2011, Gates invited Van Oppen to a conference in Santa Barbara. While there, they realized they’d both become interested in the mechanisms corals use to cope with environmental stress. Could these somehow be harnessed to help them deal with climate change?
“We chatted a lot about this idea of ‘assisted evolution,’ ” Van Oppen told me. “We sort of came up with that term.” The application Gates submitted to the Ocean Challenge was written jointly with Van Oppen. It stipulated that, if they won, half the funds would go to Hawaii and half to Australia.
I went to visit Van Oppen almost a year to the day after Gates’s death. We met at her office, at the University of Melbourne, which is situated in what used to be the university’s botany building, down the hall from a stained-glass window depicting native orchids. The conversation quickly turned to Gates.
“She was so much fun, so full of energy,” Van Oppen said. Her face darkened. “It’s still unbelievable to me that she’s gone. It really makes you realize how fragile life is.”
Since I’d been to Hawaii, the super-coral project had progressed, and so, too, had the coral crisis. The heat wave that began in Hawaii in 2014 reached the Great Barrier Reef in 2016, producing another global bleaching event. By the time it ended, the following year, more than ninety percent of the Great Barrier Reef had been affected and something like half its corals had perished. Fast-growing species were particularly hard-hit; they suffered what researchers termed a “catastrophic” collapse. Terry Hughes, a coral biologist at Australia’s James Cook University, took an aerial survey of the damage and showed it to his students. “And then we wept,” he tweeted.
In a bleaching event, it’s the corals’ relationship with their symbionts that breaks down. As water temperatures rise, the algae go into overdrive and begin to give off dangerous levels of oxygen radicals. To protect themselves, the corals expel their algae and, as a consequence, turn white. If a heat wave breaks in time, corals can attract new symbionts and recover. If it’s too prolonged, they starve to death.
The day I visited, Van Oppen had a meeting with the students and post-docs in her lab. They hailed from a Security Council’s worth of countries—Australia, France, Germany, China, Israel, and New Zealand. Van Oppen went around the table, asking for updates. Mostly people reported on the troubles they were having getting one organism or another to cooperate, and mostly Van Oppen just let them rattle on. “That’s weird,” she said finally to one post-doc whose difficulties seemed especially inexplicable.
As far as Van Oppen and her team were concerned, no member of the reef community was too small to, potentially, make a difference. Some bacteria associated with corals seem particularly adept at scavenging oxygen radicals; one idea the group was exploring was whether it might be possible, by administering some sort of marine probiotic, to make reefs more bleaching-resistant. The corals’ algal symbionts, too, might be manipulated. Of the many different types that exist—there are thousands—some seem to be associated with better heat tolerance. Perhaps it would be possible to coax corals to drop less hardy symbionts and take up with a more robust crowd, the way one might coax a teenager to find more suitable friends. Or perhaps the symbionts
could themselves be “assisted.” One of Van Oppen’s post-docs had spent years raising a symbiont variety known as Cladocopium goreaui under the sorts of conditions reefs are expected to encounter in the future. (When he showed his Cladocopium goreaui to me, I wanted to be amazed; really, though, they just looked like little clouds of dust floating in a jar.) Presumably, the Cladocopium goreaui that had come through this rough treatment possessed genetic variants that enabled them to better cope with heat stress. Perhaps “infecting” corals with these hardier strains would help them withstand higher temperatures.
“All the climate models suggest that extreme heat waves will become annual events by mid- to late-century on most reefs in the world,” Van Oppen told me. “Rates of recovery are not going to be fast enough to cope with that. So I do think we need to intervene and help them.
“Hopefully the world will come to its senses soon and actually start to reduce greenhouse gases,” she went on. “Or maybe there will be some wonderful technological invention that will solve the problem. Who knows what’s going to happen? But we need to buy time. So I see assisted evolution as filling that gap, being a bridge between now and the day when we’re really holding down climate change or, hopefully, reversing it.”
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The National Sea Simulator bills itself as “the most advanced research aquarium in the world.” It’s situated near the city of Townsville, on Australia’s eastern coast, about fifteen hundred miles north of Melbourne. Several members of Van Oppen’s team work at the facility. They were planning an experiment in assisted evolution, and so, after visiting Van Oppen’s lab, I flew up to Townsville.
It was the middle of November and large swaths of Australia were on fire. The news was filled with stories of last-minute escapes, singed koalas, and a pall of smoke over Sydney that made just breathing the equivalent of a pack-a-day habit. On the drive from the airport, I noticed patches of recently burned ground and a billboard with a picture of a raging inferno. Are You Disaster Ready? the billboard asked. I passed a zinc refinery, a copper refinery, some mango farms, and a wildlife park that advertised crocodile feedings. Dead wallabies—antipodal roadkill—littered the shoulders of the highway.
The SeaSim sits on a spit of land that juts into the Coral Sea. It would have a lovely ocean view, were it not for its lack of windows. Light at the facility is provided by computer-controlled panels of LEDs, which are programmed to mimic the cycles of the sun and moon. Most of the building is given over to tanks. These are set at waist level, like display cases in a department store. As at Gates’s lab on Moku o Lo‘e, water conditions at the SeaSim can be controlled to produce calibrated stress. In some tanks, the pH and temperature have been set to simulate conditions in the Coral Sea in 2020. Others simulate the hotter seas of 2050, and others the even grimmer conditions expected by the end of the century.
A colony of Acropora tenuis, a common species on the Great Barrier Reef
When I arrived it was late afternoon, and the place was nearly empty. I spent a while just wandering among the tanks, with my nose practically in the water. Individual corals, known unflatteringly as “polyps,” are so small they’re difficult to see with the naked eye. Even a chunk of coral the size of a child’s fist is home to many thousands of polyps, all of which are connected to each other and form a thin layer of living tissue. (The rigid part of a colony is calcium carbonate, which the corals are constantly secreting.) At the SeaSim, tank after tank was filled with a branching species, Acropora tenuis, that grows quickly and so is easier to study. Acropora tenuis forms colonies that look like miniature pine forests.
As the sun went down, both inside and outside the SeaSim, more and more people started to arrive. So as not to interfere with the light regime, everyone was wearing special red-tinted headlamps that gave off a lurid glow. This seemed appropriate, since what the crowd had come to watch was, we all hoped, an orgy.
Coral sex is a rare and amazing sight. On the Great Barrier Reef, it takes place once a year, in November or December, shortly after a full moon. During the event, called a mass spawning, billions of polyps release in synchrony tiny, bead-like bundles. These bundles, which contain both sperm and eggs, float to the surface and break apart. Most of the gametes become fish food or simply drift away. The lucky ones meet a gamete of the opposite sex and produce a coral embryo.
Tank-raised corals will, if kept under the right conditions, spawn in sync with their relatives out in the ocean. For Van Oppen’s team, the spawning offered a critical opportunity to nudge evolution along. The plan was to catch the captive corals in the act, scoop up the gamete bundles, and then, a bit like pigeon fanciers, pick and choose the couplings. One team was hoping to breed Acropora tenuis collected from the warmer, northern part of the reef with Acropora tenuis collected from the south. A second team had plans to cross altogether-different species of Acropora to create hybrids. Some of the offspring of these unnatural hookups would—so the thinking went—be more resilient than their parents.
That evening, the researchers spent hours hovering over the tanks. “This is going to be a big night,” one of the scientists who was standing watch told me. “I can feel it.” In the run-up to spawning, each polyp develops a tiny bump, making it seem as if the colony has goose pimples. This is called “setting.” As we looked on, a few of the colonies set. Then, perhaps out of modesty, perhaps out of anxiety, they held back. Gradually, people gave up and started to drift off to bed. The SeaSim has dorms for just such late nights, but these were full, so I headed out to the parking lot to drive back to Townsville. Making my way through the dark, I could hear the fruit bats screeching in the trees. The following night, I was assured, would be the big one.
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The Great Barrier Reef isn’t a reef so much as a collection of reefs—some three thousand in all—that stretches over one hundred thirty-five thousand square miles, an area larger than Italy. If there’s a more spectacular place on earth—or collection of places—I’m unaware of it. I once spent a week at a research station on a tiny island toward the southern end of the reef, right along the Tropic of Capricorn. Snorkeling off the island, which is called One Tree, I saw corals in mind-bending varieties: branching, bushy, brain-like, plate-like, shaped like fans and flowers and feathers and fingers. I also saw: sharks, dolphins, manta rays, sea turtles, sea cucumbers, octopuses with startled eyes, giant clams with leering lips, and fish in more colors than dreamt of by Crayola.
The number of species that can be found on a healthy patch of reef is probably greater than can be encountered in a similar amount of space anywhere else on earth, including the Amazon rainforest. Researchers once picked apart a single coral colony and counted more than eight thousand burrowing creatures belonging to more than two hundred species. Using genetic-sequencing techniques, other researchers tallied the number of species they could find of crustaceans alone. In one basketball-sized chunk of coral from the northern end of the Great Barrier Reef, they came up with more than two hundred species—mostly crabs and shrimp—and in a similar-sized chunk from the southern end, they identified almost two hundred and thirty species. It’s estimated that, worldwide, reefs are home to between one and nine million species, though the scientists who conducted the crustacean study concluded that even the high-end estimates probably are too low. It is likely, they wrote, that “the diversity of reefs” has been “seriously under-detected.”
This diversity is all the more remarkable in light of the surroundings. Coral reefs are found only in a band that extends along the equator, from about thirty degrees north to thirty degrees south latitude. At these latitudes, there’s not much mixing between the top and the bottom layers of the water column, and essential nutrients, like nitrogen and phosphorus, are in short supply. (The reason the water in the tropics is often so marvelously clear is that little can survive in it.) How reefs support so much diversity under such a
ustere conditions has long puzzled scientists—a conundrum that’s become known as “Darwin’s paradox.” The best answer anyone has come up with is that reef dwellers have developed the ultimate recycling system: one creature’s trash becomes its neighbor’s treasure. “In the coral city there is no waste,” Richard C. Murphy, a marine biologist who worked with Cousteau, has written. “The by-product of every organism is a resource for another.”
Since no one knows how many creatures depend on reefs, no one can say how many would be threatened by their collapse; clearly, though, the number is enormous. It’s estimated that one out of every four creatures in the oceans spends at least part of its life on a reef. According to Roger Bradbury, an ecologist at Australian National University, were these structures to disappear, the seas would look a lot like they did in Precambrian times, more than five hundred million years ago, before crustaceans had even evolved. “It will be slimy,” he has observed.
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The Great Barrier Reef is administered as a national park by the Great Barrier Reef Marine Park Authority, which goes by the awkward acronym GBRMPA (pronounced “gabrumpa”). A few months before my visit to Australia, GBRMPA had issued an “outlook report,” something it’s required to do every five years. The authority said that the reef’s long-term prospects, which it had previously characterized as “poor,” had declined to “very poor.”
Right around the time GBRMPA issued this grim assessment, the Australian government approved a gigantic new coal mine for a site a few hours south of the SeaSim. The mine, often described as a “mega-mine,” is expected to send most of its coal to India via a port—Abbot Point—situated right along the reef. Saving corals and mining more coal are, as many commentators pointed out, activities that are tough to reconcile. “The world’s most insane energy project” was Rolling Stone’s assessment.
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