Troubles Bubble Under the Sea

Colin Woodard

Tuesday, Sept. 9, 1997 | 2:37 a.m.

CABOT'S LANDING, NOVA SCOTIA -- Five hundred years ago, explorer John Cabot landed hereabouts and reported that "the seas are covered in fishes." So many, in fact, that England and France soon set up year-round fishing posts along the Atlantic Coast and in doing so began the European settlement of New England and Atlantic Canada.

Today the seas are no longer "covered in fishes." In a single generation, overfishing and poor management have devastated fish stocks in the northwest Atlantic and other regions around the world. Thirteen of the world's 15 major fishing regions have seen a decline in total catch, putting an estimated 100,000 fishers out of work and threatening the food supply of millions in developing countries.

But the deterioration of the world's fisheries is just the tip of the iceberg. There is growing concern about general declines in marine life worldwide, as many ecosystems and entire seas falter under the combined effects of a wide range of human activities.

"There is no question that there is a deterioration in the oceans' capacity to regulate planetary processes and to produce the resources we depend on," says Tundi Agardy, senior director of marine programs at Conservation International in Washington.

Overfishing, habitat destruction, climate change, and the indiscriminate dumping of sewage, fertilizers, oil, and other wastes into rivers and seas are exacting a terrible toll on marine life worldwide. Vast "dead zones" of oxygenless water have spread across highly polluted estuaries and seas. Fish stocks have deteriorated or collapsed around the world. Important habitats like wetlands and coral reefs are rapidly disappearing. Changes in sea temperatures are altering ocean currents that drive world weather patterns, possibly due to global warming.

"Scientists who are most knowledgeable about the marine environment are looking at their study sites and their data and are getting really scared," says Elliot Norse, president of the Marine Conservation Biology Institute in Redmond, Wash. "The general public is unaware of the seriousness of these problems."

The cumulative damage to marine life is most clearly seen in the world's semi-enclosed seas. Such seas typically have dense human populations ashore and a low rate of seawater "flushing" to the open ocean. Pollution, coastal development pressures, and fishing demands are concentrated with increasingly dramatic effects.

The Black Sea is a sobering example. For millennia its bountiful fish and shellfish nurtured the human civilizations that populated its shores - from ancient Greece to contemporary Turkey.

But over the past two decades, large-scale commercial fishing and agriculture have rendered the sea virtually lifeless. Twenty of 26 commercial fish species have vanished since 1970, while the anchovy harvest fell by more than 95 percent. In their place are monstrous algae blooms (which feed on human wastes) and the North American jellyfish that prey on them. Romania and Bulgaria have already sold their entire state-owned fishing fleets, and tourism is faltering as raw sewage washes onto the beach resorts that ring the sea.

The principal culprit in the decline of the Black Sea is eutrophication, an explosive growth of algae and other tiny plants triggered by an excess of sewage and other nutrients; the plants quickly consume most oxygen available in the water, suffocating animal life en masse.

This phenomenon affects lakes and coastal waters worldwide and has reached catastrophic proportions in the Black Sea. Algae blooms became so dense that they blocked light from reaching bottom-dwelling plants. Pastures of seagrass vanished, along with the mollusks, crustaceans, and flatfish that lived there. Other fish lost their breeding grounds, and the ecosystem began to collapse.

The coup de grace came in the form of a North American Mnemiopsis jellyfish - one of thousands of so-called "alien" species that are transported across the world every day in the ballast water of cargo ships. The intruders often have no natural predators and quickly displace native species, often disrupting local ecology. Zebra mussels have invaded the Great Lakes, while Chinese mitten crabs have taken over San Francisco Bay, and the tropical caulerpa weed smothers its competition at the bottom of the Mediterranean.

"We're playing ecological roulette," says James Calton, an alien species expert at Williams College in Williamstown, Mass. "Once a foreign species gets established, there's not much that can be done to get rid of it. It's like trying to put the toothpaste back into the tube."

The weakened Black Sea ecology was no match for Mnemiopsis, which gorged itself on the tiny animals at the bottom of the food chain, starved out its rivals, and soon became nearly half of the total mass of marine life in the sea.

The Mediterranean, Baltic, Yellow, and other seas suffer from similar combinations of human activities. But the countries that share these seas often have difficulty cooperating to reduce pollution and protect habitats. One such program for the Mediterranean has existed for more than 20 years, but has failed to implement its objectives or even get member countries to make agreed upon contributions.

The Yellow Sea may have the highest level of heavy-metals contamination in the world, but China and the two Koreas can't cooperate to protect their mutual resource. Then there's the cost. Baltic countries are working together, but will need a shocking $23 billion just to address the very worst sources of pollution in the Baltic basin.

On the open ocean, concern has focused on the decline of fisheries. The Rome-based United Nations Food and Agriculture Organization reports that 60 percent of the world's top 200 marine-fish resources are highly exploited or in decline.

The most dramatic collapses occurred on the famous groundfish banks off New England and Atlantic Canada. The seemingly endless stocks of cod, haddock, halibut, and flounder that first attracted Europeans to this part of the world were wiped out in a single generation. Modern technology allowed huge factory-trawlers to scoop up more fish than the sea could replace. The stocks collapsed, most fishing grounds were closed in 1992-93, and tens of thousands of fishers lost their livelihoods.

Four years later, stocks on Georges Bank are now starting to show the first signs of recovery. But from the northern tip of Labrador to the eastern shore of Nova Scotia, most damaged stocks are not recovering at all. Cod and other groundfish remain at record-low levels, their ecological roles now filled by swelling numbers of skates and dogfish, neither of which have much commercial value.

"We fished the cod to such low numbers relative to their predators that the ecological balance has shifted against them," says fisheries biologist Jeff Hutchings of Halifax's Dalhousie University. Plentiful seals (which eat young cod) appear to be consuming entire generations of cod before they reach adulthood. This, combined with record cold water temperatures (which kill fish larvae), raises concerns that the ecosystem may restabilize, but without the cod. "When you remove an entire species from an ecosystem, you've changed that system for good," says Dr. Tardy. "Usually the system will restabilize in a simpler, less resilient form. It may no longer be able to support the missing species no matter how much time goes by. And it may be less able to cope with natural or man-made stresses in the future."

Increasingly, researchers are discovering that fishing directly affects a wide range of nontarget species. Many unwanted species get caught up in nets, including other fish, seabirds, turtles, dolphins, and otters. Nearly 30 million tons of this dead or dying "by-catch" is thrown overboard by fishing boats every year - a quantity equal to a third of the world's total catch. Bottom trawls and draggers can also devastate seafloor ecology. "The bottom is torn apart as if by a giant plow," says Les Watling of the University of Maine's Darling Marine Center. "All features are flattened ... killing or disrupting all the creatures that live or depend on bottom habitats.... We don't know enough to say how this will affect marine life in general, but I think we're getting ourselves into real trouble."

Bottom creatures aren't the only ones losing their homes. Washington-based Worldwatch Institute estimates that humans have already cleared, drained, or filled half the world's salt marshes and mangroves, which act as the nurseries of the sea. Coral reefs are in decline worldwide because of water temperature changes, pollution, disease, and the use of dynamite and cyanide to stun and capture reef fish for food or aquariums. If current trends continue, most of the world's reefs will disappear before the end of the next century, according to a report to the UN Commission on Sustainable Development.

"The loss of coral reefs is something to be very concerned about," says Ira Rubinoff, director of the Smithsonian Tropical Research Institute in Panama City, Panama. "Next to the rainforests, reefs are probably the areas of the highest biodiversity on the planet. They protect shores, build islands, fix carbon, amuse tourists, and provide a wealth of food. It's a terrible loss."

The decline of species from Caribbean corals to Canadian cod eggs is being hastened by changing sea temperatures, raising concerns that global warming may also being playing a role in the decline of ocean systems. Scientists are now nearly certain that the world's use of fossil fuels is responsible for a 1 degree increase in average surface temperatures over the past century. The UN Panel on Climate Change estimates an increase of 1.5 to 6 degrees by 2100, triggering a sea-level rise of between 10 and 31 inches and putting tens of millions of people at risk.

At the poles (where temperature changes are most dramatic), there are already signs of major climatic changes that will affect marine and human life alike.

"The general predictions are that climate change will increase with latitude, and this appears to be what is happening," says Oran Young, director of the Institute of Arctic Studies at Dartmouth College in Hanover, New Hampshire.

The Arctic Sea ice cover declined by almost 6 percent between 1980 and 1994, and parts of the Antarctic ice shelves are breaking up as temperatures increase there. Scientists aren't sure if these changes are due to normal planetary climate cycles or global warming, but either way they are probably contributing to the declines of many marine species.

Even a small change in water temperature can dramatically affect the survival of fish eggs and larvae, as well as the tiny animals that fish eat. Nova Scotia Fisheries Minster Jim Barkhouse blames melting Arctic ice for the recent cooling of the Labrador Current, which appears to be killing many cod eggs in the region's damaged fisheries. "All of these problems are interconnected," says Dr. Norse. "It's usually a combination of several factors that causes the collapse of an ecosystem, which makes it very difficult to make direct cause-and-effect predictions."

Nobody has easy answers for how to reverse the decline of marine ecosystems.

Preventing eutrophication or global warming is enormously difficult because it requires significant costs and sacrifices by a wide range of industries and individuals whose livelihoods are not directly tied to the health of the oceans.

Other problems are easier to address. Most experts identify overfishing as the most serious problem affecting marine ecology. Carl Safina, director of the National Audubon Society's Living Oceans Program in Islip, N.Y., says we could see dramatic improvements by simply "doing what everyone learns as a child when they first go fishing: Throw the little ones back and don't take too many."

Putting such wisdom into practice is complicated because of disagreements over how many of a given fish can be safely taken and industry resistance to new restrictions or expensive changes in fishing gear.

Beyond 200 miles from shore, no government has jurisdiction over fish stocks, making enforcement impossible. Others are promoting the establishment of "marine protected areas" to protect vital habitats and spawning areas from mining, bottom trawling, and pollution.

"A network of protected areas, combined with good fisheries management, would serve as 'savings banks' for marine resources," says Cheri Recchia of the World Wildlife Fund Canada, which is promoting the concept.

"By protecting habitats and ecological processes in these areas, we can better ensure that the seas and oceans can continue producing the resources we rely on," Ms. Recchia says.

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