Late last summer the United Nations Environment Program published an unusual book: the first accurate atlas of the world's coral reefs. It showed that many reefs are in very bad shape, even the ones that aren't being dynamited as a fishing method. "Coral reefs are under assault," the program's executive director, Klaus Toepfer, said. "They are rapidly being degraded by human activities. They are overfished, bombed, and poisoned." The atlas was released on September 11. It did not get front-page coverage.
Not that it would have; it does not take terrorist mass murder or envelopes full of anthrax to make us forget the ocean. We have always paid it little heed—always treated it, a little paradoxically, as both an infinite food store and an infinite garbage can. But this past year we began to face up to its real limits. The coral atlas, for all its beautiful color, was not nearly so vivid as the European Union's decision last February to close a fifth of the North Sea to cod fishing during the spawning season; that hit the British right in their fish and chips. After the collapse of the Grand Banks fishery off Newfoundland in 1992 and the Georges Bank fishery in 1994, all the great stocks of Atlantic cod—the fish that fed the expansion of European civilization to America, the very fish people had in mind when they claimed the sea was inexhaustible—are close to exhausted.
And yet there is reason for optimism. Simply because we are beginning to understand the full extent of what we've been doing to the ocean, 2001 was a year full of hope—hope that we may finally be ready to slow the destruction.
"Every ecosystem I've studied is unrecognizably different from when I started," says Jeremy Jackson, a marine ecologist at the Scripps Institution of Oceanography, who has spent more than three decades among the reefs and turtle-grass meadows of the Caribbean. "I have a son who is 29, and I used to take him snorkeling on the reefs in Jamaica to show him all the beautiful corals there. I have a daughter who is 15—I can't show her anything but big heaps of seaweed."
|Fishermen in Cape May, New Jersey, unload a boat full of menhaden, herringlike fish that are a vital link in the coastal food chain. Some ecologists estimate that the menhaden population declined by more than 50 percent during the past decade.|
Photograph by Tom Tavee
It was that personal sense of loss that prompted Jackson to bring together a group of 18 other scientists with similar stories from America and Australia. The idea was to arrive at some kind of overview, a big-picture understanding they could pass on to the rest of us. The results, published last July in the journal Science,
are sobering. We have overfished coastal waters for centuries, Jackson and his colleagues found, and the effects of that overfishing have rippled through entire coastal ecosystems. In recent decades, just as we have acquired the submarines, cameras, and scuba gear that permit us to see the underwater world, the pace at which we are destroying it has accelerated frighteningly. Think of the sea around us as the Great Plains, teeming with buffalo, Jackson says; now think of the buffalo gone and the prairie turned into a monoculture of wheat—which in the case of the sea would be unpalatable plankton and jellyfish. That is the legacy we are preparing for our descendants.
Overfishing—by which Jackson and his colleagues mean excessive hunting of marine mammals and reptiles as well as fish—does not just destroy the animals we eat. Because what they used to eat no longer gets eaten, the whole ecosystem changes. The Caribbean, for instance, used to be swarming with green sea turtles. "The historical descriptions are incredible," says Jackson. "On Columbus's second voyage they feel as if they're running aground on the backs of the turtles, and they can't sail through them. And then there's this wonderful passage in a history of Jamaica in the 18th century—I can almost remember it verbatim: 'It is affirmed that vessels that have lost their way in hazy weather have navigated to the islands entirely by the sound of the beasts.'"
The cry of the green sea turtle was stilled long ago in the Caribbean; only a tiny fraction of the original population survives. When the British gained control of Jamaica in the 17th century, they began feeding turtles to slaves brought from West Africa to work the sugar plantations. Jackson unearthed historical records showing the British slaughtered as many as 13,000 turtles a year in the Cayman Islands alone. From those and other records, he estimates there were once 45 million turtles swimming around the Caribbean. "So you ask yourself the question," Jackson says, "'what did all those turtles do?'"
Among other things, they ate turtle grass. Turtle grass covers 10 to 20 percent of the shallow coastal seabed in the Caribbean; shrimp live in it, fish breed in it, and so it is an important resource to people too. According to a 17th-century natural history, turtle grass used to be four to six inches long—but that was when there were turtles around to crop it. "Now it's knee high, and it gently waves in the current," says Jackson. "And it grows from the bottom up, so the top part is the oldest, and it's rotten and foul and covered by all sorts of encrusting organisms and fungus." One of the things that grows on the rotting blades is a slime mold that in the 1980s laid waste to vast beds of turtle grass in Florida Bay and the Gulf of Mexico. Those outbreaks got fishermen very upset. The ultimate cause, Jackson believes, was a lack of turtles.
In the kelp forests off the Aleutian Islands, it is sea otters that are missing. Otters eat sea urchins, which eat kelp, and the three organisms achieve a stability—until people start eating otters and hunting them for their fur. Evidence from archaeological digs suggests that aboriginal Aleuts were wiping out local otter populations as much as 2,500 years ago, and European fur traders all but finished the job by the end of the 19th century. But in the 20th century, otter hunting was banned, and by the time Jackson's coauthor, marine biologist Jim Estes of the U.S. Geological Survey in Santa Cruz, went to the Aleutians in 1970, the otters had made a spotty comeback: Some islands had them and some didn't.
"It took about two seconds to see the difference," says Estes, recalling his first visit to one of the otterless islands. "We looked in the water and there were sea urchins everywhere—and no kelp." With no otters to eat them, the sea urchins had multiplied explosively and eaten all the kelp, converting the seabed to a pavementlike urchin barren. Both otters and kelp continued their comeback in the Aleutians until 1990, when killer whales started gobbling otters. Once upon a time, Estes believes, killer whales ate other whales, but human beings caught most of those in the North Pacific in the 1950s and 1960s. Though Estes can't prove it, he thinks the killer whales subsequently turned to other populations of marine mammals, first decimating seals and sea lions before doing the same to otters. He's not sure what they're eating now.
Elsewhere the story is similar—humans remove top consumers from the ecosystem; the ecosystem spins out of control—but the players are different. In the Chesapeake Bay, it was tall reefs of oysters rather than green turtles that once presented hazards to navigation, although there used to be lots of turtles there, too, and manatees and dolphins. Oysters feed by filtering plankton from the water, and they were so abundant in colonial times that they're estimated to have filtered all the water in the bay every three to six days. But mechanical dredging of oysters began in the late 19th century, and by the 1930s the oyster population had plummeted. The current problems of the bay, Jackson and his colleagues argue—above all, excessive plankton blooms that deplete the water of oxygen and kill fish—date from that decimation of plankton-eating oysters.
Some scientists disagree with the Jackson group's emphasis on "top-down" control of marine ecosystems. They place primary blame for the Chesapeake plankton blooms, for instance, on the huge amounts of nitrogen and phosphorus—plant nutrients—that now run into the bay from farm fields and subdivisions. But the argument is a bit academic: No one disputes that both top-down and bottom-up controls are important—or that the removal of top consumers through overfishing has had a huge effect on coastal waters. "Imagine a Serengeti," says Jackson, "where the wildebeests and the elephants and the buffalo and the hyenas and the lions are gone, and the top consumers are the termites and the locusts. That is what has happened."
So where's the hope in that?
The hope lies here: Overfishing is a catastrophe, but it's a uniquely tractable one. Nutrient runoff may well be creating dead zones in coastal waters, but we can't just stop fertilizing our fields; global warming is a serious threat to coral reefs, but we can't just stop emitting greenhouse gases, and at this point it would probably be too late. Those two assaults on the coastal ocean are backed by our whole economy. Overfishing is different. We can stop it, or at least contain it, if we really want to. And all over the world, on small scales, people are beginning to do that.
They're not doing it through the traditional techniques of fisheries management, in which scientists try to estimate how many fish there are and how many can safely be caught, and then try to enforce those estimates on recalcitrant fishermen. That's the system that gave us the collapse of the cod stocks. The technique that's working is much simpler, both to conceive and to enforce: It consists of establishing "no-take" reserves where no fishing is allowed, period. Where people have done that, they have discovered there is a free lunch. "It's been shown now from cases right across the world, from the Caribbean and from the Pacific and Southeast Asia," says marine ecologist Mark Spalding, lead author of the UNEP coral atlas. "Closing off a small patch of reef has led to massive increases in the total fish yield. You've got a great improvement in the adult fish stock in this small area, and it actually exports fish to the surrounding reef."
"A reserve is win-win; the evidence is very strong," says fisheries biologist Jim Bohnsack of the National Marine Fisheries Service in Miami, who has recently shown the benefits of a no-take zone in the lagoons around the Kennedy Space Center. "It's kind of like we've discovered penicillin for the ocean."
The marine-reserve idea got a big boost in 2000, when President Clinton issued an executive order directing the federal government to set up a system of protected marine areas, analogous to the national parks on land. Last summer the Tortugas Ecological Reserve was established 80 miles west of Key West; it covers just 197 square miles of coral reefs and fish spawning grounds, but that makes it the largest reserve yet in American waters. The Bush administration has retained Clinton's order, but right now it is not a national priority. We all have other things on our minds these days.
But we have a chance now with the ocean that we shouldn't pass up. Not to bring back a paradise in which we run aground on oysters and catch fish with buckets, and green turtles guide us to shore—those days are gone, thanks to our forefathers. "We really couldn't see what we were doing under the ocean," says Bohnsack. "We could see it on land when the forests were clear-cut and the buffalo disappeared. It just wasn't obvious until we couldn't catch cod." Our forefathers could see what they were doing to the buffalo, but they did it anyway. We have a chance to be different—to be less ignorant. A hundred years from now, what will our descendants say about us? It depends on the ocean we leave them.