by Bill Bryson
When underwater researchers realized that the Navy had no intention of pursuing a promised exploration programme, there was a pained outcry. Partly to placate its critics, the Navy provided funding for a more advanced submersible, to be operated by the Woods Hole Oceanographic Institution of Massachusetts. Called Alvin, in somewhat contracted honour of the oceanographer Allyn C. Vine, it would be a fully manoeuvrable mini-submarine, though it wouldn’t go anywhere near as deep as Trieste. There was just one problem: the designers couldn’t find anyone willing to build it. According to William J. Broad in The Universe Below: “No big company like General Dynamics, which made submarines for the Navy, wanted to take on a project disparaged by both the Bureau of Ships and Admiral Rickover, the gods of naval patronage.” Eventually, not to say improbably, Alvin was constructed by General Mills, the food company, at a factory where it made the machines to produce breakfast cereals.
As for what else was down there, people really had very little idea. Well into the 1950s, the best maps available to oceanographers were overwhelmingly based on a little detail from scattered surveys going back to 1929 grafted onto, essentially, an ocean of guesswork. The US Navy had excellent charts with which to guide submarines through canyons and around guyots, but it didn’t wish such information to fall into Soviet hands, so it kept its knowledge classified. Academics therefore had to make do with sketchy and antiquated surveys or rely on hopeful surmise. Even today our knowledge of the ocean floors remains remarkably low resolution. If you look at the Moon with a standard backyard telescope you will see substantial craters—Fracastorius, Blancanus, Zach, Planck and many others familiar to any lunar scientist—that would be unknown if they were on our own ocean floors. We have better maps of Mars than we do of our own seabeds.
At the surface level, investigative techniques have also been a trifle ad hoc. In 1994, 34,000 ice hockey gloves were swept overboard from a Korean cargo ship during a storm in the Pacific. The gloves washed up all over, from Vancouver to Vietnam, helping oceanographers to trace currents more accurately than they ever had before.
Today Alvin is forty years old, but it remains the world’s premier research vessel. There are still no submersibles that can go anywhere near the depth of the Mariana Trench and only five, including Alvin, that can reach the depths of the “abyssal plain”—the deep ocean floor—which covers more than half the planet’s surface. A typical submersible costs about $25,000 a day to operate, so they are hardly dropped into the water on a whim, still less put to sea in the hope that they will randomly stumble on something of interest. It’s rather as if our first-hand experience of the surface world were based on the work of five guys exploring on garden tractors after dark. According to Robert Kunzig, humans may have scrutinized “perhaps a millionth or a billionth of the sea’s darkness. Maybe less. Maybe much less.”
The venerable and productive mini-submarine Alvin, which was launched from Woods Hole, Massachusetts, in 1964 and has been making important discoveries ever since. (credit 18.7)
But oceanographers are nothing if not industrious and they have made several important discoveries with their limited resources—including, in 1977, one of the most important and startling biological discoveries of the twentieth century. In that year Alvin found teeming colonies of large organisms living on and around deep-sea vents off the Galápagos Islands—tube worms over 3 metres long, clams 30 centimetres wide, shrimps and mussels in profusion, wriggling spaghetti worms. They all owed their existence to vast colonies of bacteria that were deriving their energy and sustenance from hydrogen sulphides—compounds profoundly toxic to surface creatures—that were pouring steadily from the vents. It was a world independent of sunlight, oxygen or anything else normally associated with life. This was a living system based not on photosynthesis but on chemosynthesis, an arrangement that biologists would have dismissed as preposterous had anyone been imaginative enough to suggest it.
Left: An ocean vent known as the Spire disgorges a black sulphurous fluid from a depth of 3,080 metres on the mid-Atlantic Ridge. (credit 18.8a)
Right: Scientists originally assumed that no life could exist at the oceans’ deepest points because of a lack of sunlight. In fact, as a shoal of giant tube worms demonstrates, ocean vents harbour some of the most extraordinary life on the planet. (credit 18.8b)
Huge amounts of heat and energy are released by these vents. Two dozen of them together will produce as much energy as a large power station and the range of temperatures around them is enormous. The temperature at the point of outflow can be as much as 400 degrees Celsius, while a couple of metres away the water may be only two or three degrees above freezing. A type of worm called alvinellids were found living right on the margins, with the water temperature 78 degrees Celsius warmer at their heads than at their tails. Before this it had been thought that no complex organisms could survive in water warmer than about 54 degrees Celsius, and here was one that was surviving warmer temperatures than that and extreme cold to boot. The discovery transformed our understanding of the requirements for life.
It also answered one of the great puzzles of oceanography—something that many of us didn’t realize was a puzzle—namely, why the oceans don’t grow saltier with time. At the risk of stating the obvious, there is a lot of salt in the sea—enough to bury every bit of land on the planet to a depth of about 150 metres. It had been known for centuries that rivers carry minerals to the sea and that these minerals combine with ions in the ocean water to form salts. So far no problem. But what was puzzling was that the salinity levels of the sea were stable. Millions of gallons of fresh water evaporate from the ocean daily, leaving all their salts behind, so logically the seas ought to grow more salty with the passing years, but they don’t. Something takes an amount of salt out of the water equivalent to the amount being put in. For a very long time, no-one could figure out what could be responsible for this.
Alvin’s discovery of the deep-sea vents provided the answer. Geophysicists realized that the vents were acting much like the filters in a fish tank. As water is taken down into the Earth’s crust, salts are stripped from it, and eventually clean water is blown out again through the chimney stacks. The process is not swift—it can take up to ten million years to clean an ocean—but if you are not in a hurry it is marvellously efficient.
Perhaps nothing speaks more clearly of our psychological remoteness from the ocean depths than that the main expressed goal for oceanographers during International Geophysical Year, 1957/8, was to study “the use of ocean depths for the dumping of radioactive wastes.” This wasn’t a secret assignment, you understand, but a proud public boast. In fact, though it wasn’t much publicized, by 1957/8 the dumping of radioactive wastes had already been going on, with a certain appalling vigour, for over a decade. Since 1946, the United States had been ferrying 55-gallon drums of radioactive gunk out to the Fallarone Islands, some 50 kilometres off the California coast near San Francisco, where it simply threw them overboard.
It was all quite extraordinarily sloppy. Most of the drums were exactly the sort you see rusting behind petrol stations or standing outside factories, with no protective linings of any type. When they failed to sink, which was usually, navy gunners riddled them with bullets to let water in (and, of course, plutonium, uranium and strontium out). Before this dumping was halted in the 1990s, the United States had dumped many hundreds of thousands of drums into about fifty ocean sites—almost fifty thousand of them in the Fallarones alone. But the United States was by no means alone. Among the other enthusiastic dumpers were Russia, China, Japan and nearly all the nations of Europe.
Blue whales are the largest animals on Earth—indeed, the largest that have ever lived—and yet much about them is unknown, including how they communicate and where they spend most of the year. (credit 18.9)
And what effect might all this have had on life beneath the seas? Well, little, we hope, but we actually have no idea. We are astoundingly, sumptuously, radiantly ignorant of life beneath the seas. Ev
en the most substantial ocean creatures are often remarkably little known to us—including the most mighty of them all, the great blue whale, a creature of such leviathan proportions that (to quote David Attenborough) its “tongue weighs as much as an elephant, its heart is the size of a car and some of its blood vessels are so wide that you could swim down them.” It is the most gargantuan beast the Earth has yet produced, bigger even than the most cumbrous dinosaurs. Yet the lives of blue whales are largely a mystery to us. Much of the time we have no idea where they are—where they go to breed, for instance, or what routes they follow to get there. What little we know of them comes almost entirely from eavesdropping on their songs, but even these are a mystery. Blue whales will sometimes break off a song, then pick it up again at exactly the same spot six months later. Sometimes they strike up with a new song, which no member can have heard before but which each already knows. How they do this and why are not remotely understood. And these are animals that must routinely come to the surface to breathe.
Safety officers check radioactive waste before consigning it to underground trenches. Between 1946 and the 1990s, much nuclear waste was dumped into the oceans, usually in unprotected 55-gallon drums. (credit 18.10)
For animals that need never surface, obscurity can be even more tantalizing. Consider our knowledge of the fabled giant squid. Though nothing on the scale of the blue whale, it is a decidedly substantial animal, with eyes the size of soccer balls and trailing tentacles that can reach lengths of 18 metres. It weighs nearly a tonne and is Earth’s largest invertebrate. If you dumped one in a small swimming pool, there wouldn’t be much room for anything else. Yet no scientist—no person, as far as we know—has ever seen a giant squid alive. Zoologists have devoted careers to trying to capture, or just glimpse, living giant squid and have always failed. They are known mostly from being washed up on beaches—particularly, for unknown reasons, the beaches of the South Island of New Zealand. They must exist in large numbers because they form a central part of the sperm whale’s diet, and sperm whales take a lot of feeding.1
What little we know of giant squid comes almost exclusively from bodies washed up on beaches, as with this specimen in Tasmania. (credit 18.11)
According to one estimate, there could be as many as 30 million species of animals living in the sea, most still undiscovered. The first hint of how truly abundant life is in the deep seas didn’t come until as recently as the 1960s with the invention of the epibenthic sled—a dredging device that captures organisms not just on and near the sea floor but also buried in the sediments beneath. In a single one-hour trawl along the continental shelf, at a depth of about 1.5 kilometres, Woods Hole oceanographers Howard Sandler and Robert Hessler netted over twenty-five thousand creatures—worms, starfish, sea cucumbers and the like—representing 365 species. Even at a depth of nearly 5 kilometres, they found some 3,700 creatures representing almost two hundred species of organism. But the dredge could capture only those things that were too slow or stupid to get out of the way. In the late 1960s a marine biologist named John Isaacs had the idea of lowering a camera with bait attached to it, and found still more, in particular dense swarms of writhing hagfish, a primitive eel-like creature, as well as darting shoals of grenadier fish. Where a good food source is suddenly available—for instance, when a whale dies and sinks to the bottom—as many as 390 species of marine creature have been found dining off it. Intriguingly, many of these creatures were found to have come from vents up to 1,600 kilometres away. These included such types as mussels and clams, which are hardly known as great travellers. It is now thought that the larvae of certain organisms may drift through the water until, by some unknown chemical means, they detect that they have arrived at a food opportunity and fall onto it.
An exciting but decidedly overblown rendering of a giant octopus from an 1805 French work on marine life. (credit 18.12)
So why, if the seas are so vast, do we so easily overtax them? Well, to begin with, the world’s seas are not uniformly bounteous. Altogether less than a tenth of the ocean is considered naturally productive. Most aquatic species like to be in shallow waters, where there are warmth and light and an abundance of organic matter to prime the food chain. Coral reefs, for instance, constitute well under 1 per cent of the ocean’s space but are home to about 25 per cent of its fish.
Elsewhere, the oceans aren’t nearly so rich. Take Australia. With 36,735 kilometres of coastline and over 23 million square kilometres of territorial waters, it has more sea lapping its shores than any other country, yet, as Tim Flannery notes, it doesn’t even make it into the top fifty among fishing nations. Indeed, Australia is a large net importer of seafood. This is because much of Australia’s water is, like much of Australia itself, essentially desert. (A notable exception is the Great Barrier Reef off Queensland, which is sumptuously fecund.) Because the soil is poor, it produces practically no nutrients in its run-offs.
A type of fish known as a blenny cautiously peers out from a brain coral in the Dutch Antilles. Coral reefs take up less than 1 per cent of the oceans’ space, but provide homes for a quarter of their fish. (credit 18.13)
Even where life thrives, it is often extremely sensitive to disturbance. In the 1970s, fishermen from Australia and, to a lesser extent, New Zealand discovered shoals of a little-known fish living at a depth of about 800 metres on their continental shelves. They were known as orange roughy, they were delicious and they existed in huge numbers. In no time at all, fishing fleets were hauling in 40,000 tonnes of roughy a year. Then marine biologists made some alarming discoveries. Roughy are extremely long-lived and slow-maturing. Some may be 150 years old; any roughy you have eaten may well have been born when Victoria was Queen. Roughy have adopted this exceedingly unhurried lifestyle because the waters they live in are so resource-poor. In such waters, some fish spawn just once in a lifetime. Clearly these are populations that cannot stand a great deal of disturbance. Unfortunately, by the time this was realized the stocks had been severely depleted. Even with good management it will be decades before the populations recover, if they ever do.
Orange roughy, a sluggish but delicious ocean fish, were caught in vast numbers before marine biologists realized how desperately susceptible to extinction they were. (credit 18.14)
Elsewhere, however, the misuse of the oceans has been more wanton than inadvertent. Many fishermen “fin” sharks—that is, slice their fins off, then dump them back into the water to die. In 1998, shark fins sold in the Far East for over $110 a kilo, and a bowl of shark-fin soup retailed in Tokyo for $100. The World Wildlife Fund estimated in 1994 that the number of sharks killed each year was between 40 million and 70 million.
As of 1995, some 37,000 industrial-sized fishing ships, plus about a million smaller boats, were between them taking twice as many fish from the sea as they had just twenty-five years earlier. Trawlers are sometimes now as big as cruise ships and haul behind them nets big enough to hold a dozen jumbo jets. Some even use spotter planes to locate shoals of fish from the air.
Shark fins bagged for sale in Hong Kong. The fins are sliced from the sharks by fishermen who then throw the fish back into the water to die. (credit 18.14a)
It is estimated that about a quarter of every fishing net hauled up contains “by-catch”—fish that can’t be landed because they are too small or of the wrong type or caught in the wrong season. As one observer told The Economist: “We’re still in the Dark Ages. We just drop a net down and see what comes up.” Perhaps as much as 22 million tonnes of such unwanted fish are dumped back in the sea each year, mostly in the form of corpses. For every kilogram of shrimp harvested, about four kilograms of fish and other marine creatures are destroyed.
Large areas of the North Sea floor are dragged clean by beam trawlers as many as seven times a year, a degree of disturbance that no ecosystem can withstand. At least two-thirds of species in the North Sea, by many estimates, are being overfished. Across the Atlantic things are no better. Halibut once abounded in such numbers
off New England that individual boats could land 20,000 pounds of it in a day. Now halibut is all but extinct off the northeast coast of America.
Nothing, however, compares with the fate of cod. In the late fifteenth century, the explorer John Cabot found cod in incredible numbers on North America’s eastern banks—shallow areas of water popular with bottom-feeding fish like cod. The fish existed in such numbers, an astonished Cabot reported, that sailors scooped them up in baskets. Some of the banks were vast. Georges Banks off Massachusetts is bigger than the state it abuts. The Grand Banks off Newfoundland is bigger still, and for centuries was always dense with cod. They were thought to be inexhaustible. Of course they were anything but.
By 1960, the number of spawning cod in the north Atlantic had fallen to an estimated 1.6 million tonnes. By 1990 this had sunk to 22,000 tonnes. In commercial terms, the cod were extinct. “Fishermen,” wrote Mark Kurlansky in his fascinating history, Cod, “had caught them all.” The cod may have lost the western Atlantic for ever. In 1992, cod fishing was stopped altogether on the Grand Banks, but as of autumn 2002, according to a report in Nature, stocks had still not staged a comeback. Kurlansky notes that the fish of fish fillets or fish fingers was originally cod, but then was replaced by haddock, then by redfish and lately by Pacific pollock. These days, he notes drily, “fish” is “whatever is left.”
