Into the blue

The dive master said the sea floor was 3,000 feet straight down.

“You don’t come back from that depth,” he said, laughing blackly.

With that thought, I stepped off the boat. The bright blue sky disappeared. My eyes opened on the deep blue of the Coral Sea.

The water was nearly clear as glass. Twenty feet below my flippers, two 10-foot gray reef sharks and more than a dozen smaller black- and white-tip reef sharks patrolled in smooth ellipses.

My dive partner Kyoko Kishi hung weightless in the water 10 feet below, waiting. Her exhalation rose in a silvery cascade toward a reunion with the surface.

When I reached her, we exchanged OK signs and followed the other divers down, past the sharks, to a horse-shoe-shaped shelf on Osprey Reef, where we sat down like sports fans in a stadium. Soon 30 divers had perched there on the lip of an extinct volcano. Sharks gathered overhead, vehicles of muscle and cartilage that glided as effortlessly as eagles in the sky.

Nothing in 400 million years of finely honed instincts tells sharks that an awkwardly moving creature attached to a metal can and blowing bubbles is edible. But they’re not stupid. They were circling because they knew food was coming.

Soon a crewmate from our dive boat, the Taka, would dump a half dozen 10-pound tuna heads chained to a cable over the side of a raft, which we could see floating overhead. We would then witness the drama of a feeding frenzy on one of the world’s great natural stages – the Great Barrier Reef.

The reef is a most unusual wilderness, and not just because it’s underwater, or that it’s the largest living structure on Earth, or that it’s populated by a parade of improbable animals. It’s because it’s so robust. At a time when many coral reefs have died off or are in danger of it, the Great Barrier Reef thrives. It is one of the world’s last best places: an oceanic ecosystem in its glory.

As pristine places like the Great Barrier Reef become more scarce, they also become more desirable. Nearly 2 million people visit the reef each year, making it one of Australia’s most popular attractions. Tourism here is a powerful economic force. Marine tourism alone generates more than $1.3 billion Australian dollars annually, and land-based tourism on the coast near the reef brings in nearly $3 billion more. Travelers are drawn to the spectacles a healthy reef affords. Such as a sizable population of big predators.

With a barely visible splash, the tuna heads hit the water, and the sharks went into a frenzied scrum. The biggest ones, who were first with a jaw grip, tugged and twisted at the chained-up tuna heads. Others charged the knotted crowd, vying for an angle on the meat.

When cruising, sharks look menacing, but stately. With hardly a visible flick of their tail fins, they swim with liquid grace. Now, they bolted past at lightning speed. Reliable estimates suggest some sharks can hit 40 miles per hour; as one flew by with a hunk of tuna head in his mouth, knocking over one of the seated divers with the force of his wake, that seemed entirely plausible.

In five minutes, the thrashing was over. The cable hung empty and slack. The sharks dispersed.

Kishi and I slowly made our way back to the boat, surfaced and spit out our regulators, exchanging the dry, sterile air of the tanks for the humid, oxygen-rich atmosphere of the tropics. We stripped out of our tanks, buoyancy-control vests, weight-belts, masks and wet suits. Still, having dropped 45 pounds of gear, as I headed into the galley for lunch, I felt the terrible burden of gravity. For the past 35 minutes underwater, I’d been weightless.

The Taka is one of the biggest of the dozens of live-aboard dive boats that ply the Coral Sea. It accommodates as many as 30 passengers, along with a crew of 10. Divers from Egypt, Japan, Poland, Spain, Finland, the Netherlands, England, Australia, New Zealand, Canada and the United States filled every available bunk and suite.

The usual quirks of group travel applied. The Finnish woman dove in her pajamas instead of a wet suit, and she generally ignored her assigned dive buddy, the Egyptian doctor, who was exasperated by her unpredictability. The Polish woman was a rock star going by the name Dominika; she showed us one of her videos on the big-screen TV in the galley. Sporting teased-up blond hair and strutting in a skin-tight pinstripe suit and stiletto heels, she snarled, “I’m going to unleash myself, release myself on the world.” There was something about her feral expression that made the shark feed seem almost genteel.

Starting in Cairns, the most popular tourist port on Queensland’s coast, the Taka traveled 200 miles to Osprey Reef and back, stopping at the prettiest, most pristine dive sites available en route. Nothing that happened in my four days on the boat compared with seeing the reefs themselves – conglomerations of life that can be seen from outer space. I often found myself hovering in one spot, admiring the way the reef thrums with creation: Seussian Christmas tree worms swaying in the current, a neon-painted slug called a nudibranch scooting across a plate coral, translucent cleaner shrimp picking the nits off a gasping moray eel in his chosen crevice. Every square inch is occupied by somebody trying to make a living.

On one of our last dives, however, we got a glimpse of what a distressed reef looks like.

The site, called the Maze, was fairly close to Cairns. We arrived in late afternoon. There were four other boats already tied off to the permanent moorings, and a large glass-bottomed pontoon was anchored over a coral pillar, giving day-trippers a way to see the reef without getting wet.

Just after dark, we geared up. The water teemed with schooling fish, drawn to the boat by big spotlights on the roof. Kishi and I jumped in. Carrying flashlights, we explored the pillars of coral near the boat. Broken pieces of staghorn coral lay in the sand. Brown-green algae covered some areas of the reef, obviously dead. Other areas were a ghostly white – stripped of all color. It made me sad and curious; what went wrong?

I wanted a clearer look at the big picture. To find some answers, I drove to the rough-around-the-edges working port of Townsville, where Australia’s premier marine biologists labor at the Australian Institute of Marine Science (AIMS) and where the Great Barrier Reef Marine Authority is headquartered.

In two days of interviews with scientists, a couple of themes emerged. One was that even though the Great Barrier Reef is the healthiest in the world, it faces real threats. The second one was, the way scientists understand and manage the reef has changed dramatically in the past couple of years, perhaps offering a model for how some of the world’s other coral reefs – bountiful producers of food as well as beauty – might also be preserved.

According to the Status of Coral Reefs of the World report, delivered last year by an international group of marine scientists, 20 percent of the world’s reefs are gone, 24 percent are in imminent danger of collapse from human pressure, and 26 percent are under longer-term threat of collapse. Why? Most damage has come from global temperature change, runoff from overdeveloped coastal areas and overfishing. The Great Barrier Reef isn’t immune to those pressures.

“Most of the Great Barrier Reef is in good shape, but several big animals aren’t,” said Katharina Fabricius, a senior research scientist at AIMS. She said the dugong, or sea cow, population is currently 4 percent of what it was 40 years ago, mostly because of habitat loss. The shark population has been steadily declining by 4 percent a year because of overfishing, she said. Marine turtles have also suffered serious losses from getting caught in fishing nets and loss of nesting sites on rapidly developing beaches.

Runoff is a natural part of the coastal environment; soil and plant matter washed into the sea from rivers provides nutrients for all kinds of small creatures, but it has become a problem along Queensland’s rapidly developing coast.

“The amount of sediment and nutrients flowing into the sea is four times what it was before Europeans arrived,” said David Wachenfeld, director of science and technology information for the marine park authority. Corals need clean, clear water to be healthy. He said some reefs near shore had been damaged by runoff from towns, sugar-cane fields and pastures.

The biggest threat is the hardest one to address. Global climate change endangers all coral reefs because corals – animals related to jellyfish – live in a very narrow temperature range. “The corals are now living in the 1 to 2 degrees of their upper thermal limits,” said Janice Lough, a research scientist at AIMS. “They are at risk in the summer season when the sun is at its hottest.”

Lough cited major “coral bleaching” episodes in the summers of 1998 and 2002. Coral relies on species of algae that help them assimilate nutrition, and also give them bright colors. When water temperatures rise above a certain level, the algae becomes toxic to the coral, and the coral must eject it temporarily to survive. In 1998, 42 percent of the whole Great Barrier Reef bleached. In 2002, 53 percent of the reef bleached. In both cases, most of the coral eventually recovered. But as temperatures rise – and an overwhelming majority of scientists accept as fact that they are rising – the bleaching episodes will become more frequent and more damaging, Lough said. She was not optimistic that the reef would survive long term, but was hopeful that policy changes made now will help it last as long as possible.

“Reefs can recover from disturbances,” Lough said, “but they need to be healthy reefs to begin with.”

Which brings us to that sea change in how the reef is understood.

In the past five or six years, Australian scientists have reached a consensus that the reef is just one part of an ecosystem that stretches from the coastal mountains to the deepest parts of the Coral Sea.

That holistic view has led to big changes. Last year the marine park authority identified 70 biological zones. The zones include areas that previously weren’t considered important – such as river mouths, tidal flats and empty stretches of sea floor. Then the authority closed 33 percent of the marine park to fishing of any kind, drawing up a checkerboard map of no-take areas that includes patches of all 70 zones. The government is also taking action to reduce runoff through programs to restore wetlands and replant river banks with trees, he said.

“Coral is visually appealing, iconic, but it only makes up 6 percent of the whole reef ecosystem,” said Wachenfeld. “All the rest is necessary to support it. The mangrove swamps, sea-grass beds and flat, sandy bottoms support life at various stages.”

As an example, he cited the life cycle of the red emperor, a tasty fish that is as popular with people as it is with bigger fish. The adult lives and spawns on the reef. The eggs drift to shore, lodging in sea-grass beds, which later provide a safe place for hatchlings to grow. The young red emperors migrate back to the reef as they get bigger, using various environments for shelter along the way. Like all animals on the reef, the red emperor eats and is in turn eaten, doing its part to keep the system in balance.

Wachenfeld and other scientists said closing off large portions of the park was not popular with local anglers. “Nearly everyone agreed there was a problem, but no one wanted their fishing spot closed,” he said. “There are still a lot of angry people out there. But as a consequence, they’ll still be fishing here in 20 years.”

Controversy over the rulings is limited to the anger of local anglers; a majority of Australians supports the efforts to preserve the reef. The scientific community is united as well: Of the dozens of papers I found and reviewed, only one disagreed with the new approach to preserving the reef.

Wachenfeld and others said that the political will to create such strong protections came, in large part, because tourism brings in much more money than commercial or sport fishing. (Marine tourism on the reef alone brings in about $1.3 billion annually; commercial and sport fishing combined, about $304 million.)

“It would be nice if it were some fine ideal that prompted the shut-down in the fishery,” said Paddy Colwell, a divemaster in Cairns who teaches a popular night class for tourists about the reef. “But it was money, pure and simple.”

He pointed out that with a sparse population, high incomes and a diverse economy, Australia is one of the few countries in the world that can afford to preserve its reef. In countries like the Philippines and Indonesia, over-population and poverty forces desperate people to scratch for whatever food they can. It’s common in Southeast Asia to fish with dynamite, for example, a practice that is very effective, but that destroys coral in the process.

“Indonesia’s population has doubled in the past 30 years,” Colwell said. “How are you going to tell them to stop fishing with dynamite?”

In other words, it doesn’t matter if you’re a shark or a human being; when you’re hungry, a fish is food. As long as there’s more money to be made in looking at fish than there is in eating them, that fact is the Great Barrier Reef’s brightest ray of hope.

— Minneapolis Star Tribune. November 13, 2005