Coral in Peril

Text by Douglas H. Chadwick
Photographs by David Doubilet

The world’s coral reefs touch our lives in many ways, yet an alarming number of them have been degraded or destroyed.

Up on the shoulder of the Bighorn Mountains near the Wyoming-Montana line, the wind gets to whistling at a pretty good clip. It had all but drifted over the sagebrush with late winter snow, and we’d half-buried a pickup truck in the stuff. We dug for a while, got unstuck, wheeled on to Bighorn Cave in a plume of cold powder, unpacked climbing gear, and roped straight down 90 feet [27 meters] into blackness. Don Minchow, a local spelunker, led the way deeper while the beam from my headlamp set gardens of gypsum crystals ablaze. At the end of one long crawl I found him on his back pointing up at ribbed crescents embedded in the stone.

“Clams,” Minchow said as I scrunched alongside. Then we began noticing sections of coral. Though close to a thousand miles [1,600 kilometers] from the nearest ocean and 5,000 feet [1,500 meters] higher, we had made our way to a warm-water reef. It just happened to be about 350 million years old.

Thrust upward from seas that covered North America’s interior during the Mississippian epoch, this thick limestone layer, the Madison formation, is part of a geologic landscape that reaches from Idaho to the Dakotas and north into Canada. Travel Florida’s Overseas Highway between Key Largo and Key West and you’re atop coral reefs built 125,000 years ago during the Pleistocene. More fossil reefs of various ages emerge as outcrops from the Caribbean to the Northwest Territories. Throughout geologic history a variety of marine organisms have created reefs. But today the key element is corals, the animals that helped make the world.

Coral reef limestone surrounds us in more ways than one. Cut into masonry, it houses families and institutions. Crushed, it becomes a major ingredient of cement. As marble, it further metamorphoses under sculptors’ hands into pure art. Living coral reefs cover 360,000 square miles [580,000 square kilometers], an area slightly smaller than British Columbia, yet they host one of every four ocean species known. Along with tropical rain forests, these submarine animal forests are the most diverse ecosystems on the planet. We know rain forests are vanishing fast. How are the coral reefs doing? To find out, I lined up travels that would lead me to some of the answers.

In addition to sea anemones and most jellyfish, the group of tentacled creatures known as cnidarians includes soft corals, sea fans, and solitary corals, some of which thrive in cold, dark waters; hydrocorals and fire corals; black corals with horny skeletons; and the true reefbuilders—hard, or stony, corals. Close to a thousand stony coral species currently exist, in distinctive shapes ranging from mushrooms to moose antlers, cabbages, tabletops, wire strands, fluted pillars, and wrinkled brains. These structures, referred to as coral heads, are actually colonies of individual polyps, each of which secretes a limestone cup around itself for protection.

Colonies grow slowly, seldom more than a half inch [1.3 centimeters] a year. Some atolls, accreting in stages for at least 50 million years, now stand almost a mile [1.6 kilometers] thick. It would seem safe to say that time is on the corals’ side. But in just the past few decades, pollution, overfishing, dense coastal development, and other forces have destroyed a tenth of the Earth’s coral reefs and seriously degraded almost a third. At this rate, scientists warn, nearly three-quarters could lie in ruins within 50 years.

Vacationers who swap snow shovels for snorkels are a vital source of income for many tropical countries. But the reasons for keeping coral communities healthy extend well beyond saving colorful undersea gardens for tourists or protecting wildlife for its own sake.

As John McManus, an ecologist with the International Center for Living Aquatic Resources Management, explained, “Reef fish make up perhaps 10 percent of the global fish catch. Together with mollusks, urchins, and other reef foods they support 30 to 40 million people. We’re talking about the survival of families, villages, whole cultures—about whether kids have sufficient protein to properly nourish growing brains.”

More than three billion people—the majority of humankind—occupy coastal regions. The figure is expected to double by 2050, with most of the increase coming in the tropics, where half the world’s shorelines are found. A third of those coasts are associated with coral reefs. Because reefs often grow close enough to the surface to break up incoming waves, their value in buffering lands from storm surges and daily erosion reaches beyond calculation. At the same time, the relatively calm back-reef areas foster sea grass beds and mangrove forests, two enormously productive habitats that serve as nurseries for the juvenile stages of still more fish and shellfish.

Humanity’s ties to the creatures living around coral reefs may multiply as medical research taps more of the organisms at home there. Some have already yielded compounds active against inflammations, asthma, heart disease, leukemia, tumors, bacterial and fungal infections, and viruses, including HIV. Studies found that chemicals used by sea slugs and certain sponges to repel fish also work on land as insecticides. Screening the venom of tropical cone snails for pharmaceutical properties turned up a possible nonaddictive substitute for morphine. Sea whips, related to true corals, offer a potential painkiller as well, while coral skeletons themselves are being investigated as substrate for bone grafts. Finally, reefbuilding extracts roughly half the calcium entering the world’s seas. Corals secrete calcium carbonate—limestone—on a scale massive enough to influence ocean chemistry and affect carbon dioxide levels in the atmosphere and, thus, the health of the planet as a whole.

How, then, did we come to be presiding over the collapse of one coral realm after another?

Together, the Indonesian and Philippine archipelagoes contain about 21,000 islands and nearly one-fifth of the Earth’s coral reefs. There are none richer or more complex. A single bay in an Indo-Pacific sea may contain twice as many coral and fish species as grace the entire Caribbean—providing you can still find healthy reefs to compare. Fewer than 10 percent of Indonesia’s remain in prime condition. In the Philippines the figure has fallen below 5 percent.

On the little Philippine island of Olango, I listened to Ramon Maloloyon describe fishing with cyanide for the aquarium trade. He used to squirt the chemical onto coral colonies, then pry them apart with a crowbar to capture stunned fish hiding in the crevices. Thousands of his countrymen did the same, starting in the 1960s, until they were putting 330,000 pounds [150,000 kilograms] of poison onto 33 million coral heads yearly. The aquarium industry annually sells 200 million U.S. dollars’ worth of live-caught marine stock worldwide. Its biggest market is the United States. The business is perfectly legal, though the use of cyanide is not. More than half the fish die during capture and transport.

Larger live specimens from the reefs began going to places like Hong Kong so fashionable diners could pick them out of a restaurant tank to eat, paying hundreds of dollars for the privilege. Soon humphead wrasses, giant groupers, and other choice fish that can be filleted into multiple servings were selling for small fortunes. Providing such fare burgeoned into a billion-dollar-a-year industry. Commercial fleets that used to work offshore with nets took on diving crews and came to join in the plunder of the reefs.

When Maloloyon was diving for fish, he used homemade fins and breathed through a “hookah”—a thin plastic tube attached to a boat’s air compressor. As fish got scarcer, he had to search deeper. No one told him how nitrogen bubbles can sizzle through your tissues if you come up too fast. He suffered the bends four times. Then a fifth. “I went down 70 meters [230 feet] and worked for about two hours,” he told me. “I came straight up. A minute after I got in the boat, I went into shock.” His legs have been paralyzed ever since. About one in every ten cyanide divers ends up incapacitated or dead. Maloloyon had been after a flame goby, also known as the elegant firefish—a dazzling species that can bring nearly U.S. $50 retail. His share? “Ten pesos,” around 50 U.S.cents at the time.

Some poison fishermen are being retrained by the International Marinelife Alliance, a Philippines-based conservation organization, to catch fish in hand-carried nets. After diving with them, I floated along for miles with one arm hooked around the bamboo outrigger of the alliance’s boat. Through my mask all I saw was a white rubble of shattered coral heads.

When I lifted my head for a break, I saw what was causing the destruction—and what might have broken my eardrums had I been submerged. Boatmen chasing a school of fish nearby started lobbing bottles of homemade explosives into the sea. A marine official aboard our craft shot a pistol round over the poachers’ heads. They fled. I stroked down to inspect the bottom. Fusilier fish drifted past, some spinning aimlessly in convulsions, others already belly up, their electric blue stripes fading to gray. But I couldn’t pick out the fresh blast sites among all the other recent craters.

The lethal combination of explosives and poisons—on top of overfishing with nets, traps, and spearguns—has become epidemic from remote South Pacific islands to the coast of East Africa and beyond. Meanwhile, living coral reefs are being mined for construction material, displaced by shoreline projects, and fragmented for sale as aquarium ornaments or jewelry. A far greater number of reefs are suffering from chemical runoff and increased silt loads caused by intensive farming and logging.

The once high fish yields of American Samoa’s reefs have declined nearly 70 percent in recent years. The culprits: overfishing, pollution, and sediment runoff. Nine-tenths of the corals on Jamaica’s northwest coast have been killed by hurricanes and diseases, but the reefs have no chance for recovery because they’ve been smothered by algae. The algae are nourished by pollution from coastal development and agricultural runoff, and overfishing has removed some species that kept the algae grazed down. Along Florida’s Keys, I inspected reefs afflicted by a welter of rapidly spreading diseases. Aspergillosis, caused by a fungus that may have invaded from land; white plague type II, from a just discovered bacterium; and a number of other previously unknown coral ailments are also beginning to show up off other shores. “Something seems to be making colonies more and more susceptible to illness,” said James Cervino, a marine biologist who has been tracking outbreaks in the Caribbean with Tom Goreau, director of an environmental group called the Global Coral Reef Alliance.

That something could be accumulated environmental stress. Corals deal with excess silt, pollutants, and similar irritants by secreting more of the mucous protein that coats their outer tissues. This costs the corals energy. Worse, viruses, bacteria, and fungi consider the slimy layer a fine place to breed. As corals continue to deplete their metabolic reserves and microbes prosper, the stage is set for infection.

All too many fishermen in all too many countries dump not only cyanide but bleach and other toxics directly onto coral reefs as a way of getting fish. But it was a different kind of bleaching that first caused public alarm. Huge tracts of coral reefs suddenly and inexplicably began to turn deathly white during the 1980s, even in relatively undisturbed areas.

Scientists soon realized the corals weren’t done for; they had only expelled the single-celled, symbiotic organisms known as zooxanthellae, leaving limestone skeletons showing through transparent tissues. Corals bleach as a reaction to sharp changes in salinity and also in response to heavy ultraviolet radiation, despite possessing several kinds of natural sun-blocking compounds that are being studied for possible human use. However, most bleaching has been linked to abnormally high local ocean temperatures such as those spawned by El Niņo.

Corals are structurally fragile, easily damaged by a carelessly tossed boat anchor or snorkeler’s fin, but biologically resilient. They have to be to have endured over time in the face of hurricanes, volcanoes, coastal landslides, and predators like the colony-devouring crown-of-thorns sea stars. Given time, bleached corals can regain their color and their potential for growth and reproduction. Then again, they may succumb if bleaching episodes are prolonged or recur too often, or if the colonies are trying in the meantime to cope with heavy metals, pesticide residues, or algae stimulated by nutrients flushed from coastal rivers and farms. Wherever corals are weakened by these factors, the possibility of disease looms larger.

Whether you prefer to believe that the underlying cause is natural or industrial, average global temperatures have been on the rise. Coral reefs may be warning us to pay closer attention, just as they can signal the pressures that modern populations are placing on tropical resources. Yet all along, the animals that helped build the world show us as plainly as any creatures can that environmental protection is not at odds with human needs.

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