Secret treasures of the deep

Posted: 11 October 2000

Author: Sylvia Earle

Now is the time to uncover the mysteries of the ocean deep - the largest habitat on earth - says Sylvia Earle, internationally- renowned scientist and author.

Half a century ago, the deep sea was thought to be as remote and inaccessible as the far side of the moon. According to international law, the seabed below a few thousand feet was known as res nullius - incapable of occupation, a no-man's land.

Curiously, despite the enormous technological advances in recent years that have taken humankind to the moon, planted instruments on Mars and lofted sensors far beyond our own solar system, the deep sea remains largely unknown, unexplored, and generally inaccessible. Despite impressive discoveries and greatly improved mapping techniques in recent years, less than one per cent of the deep sea actually has been seen, let alone explored. The difficulty of gaining knowledge of the deep sea is conveyed by Willard Bascom's description of a special place in the South Pacific:

"The Tonga Trench is 15 to 30 miles wide and 7 miles deep...A mile deeper than Everest is high. As deep as seven Grand Canyons but with much steeper sides. Higher than a stack of 30 Empire State Buildings."

To sample this heroic crack, Bascom lowered a tube six feet long, weighted with lead - a gravity corer - over the side of a research ship. Hours of effort yielded one small chip of basalt.

Descending into the sea, twice atmospheric pressure - 29.4 pounds per square inch (psi) is reached at 33 feet. At 3,028 feet, about half a mile - a depth first attained in the 1930's by zoologist William Beebe and engineer Otis Barton in a small bathysphere - the pressure is 1,360 psi.sea explorationDeep sea exploration© Flip Schulke/Planet Earth PicturesDuring a single dive, sperm whales dive to as much as a mile beneath the surface and in so doing, experience a range of pressure from a few pounds to more than one ton on each square inch of their big bodies. At seven miles, the deepest sea, the pressure is about 16,000 psi.

Building systems to withstand the such pressures presents formidable challenges, but the technology and engineering skills exist to master the problems. Ironically, a successful roundtrip journey was made many years ago, in 1960, when US Navy Lieutenant Don Walsh and Swiss engineer, Jacques Piccard, travelled in the bathyscaphe, Trieste, to the bottom of the deepest place in the ocean, the Challenger Deep in the Mariana Trench, 35,800 feet down. They remained there for about half an hour.

Not until 1996 was there an attempt to return, remotely, with a large robotic vehicle, Kaiko, designed and operated by the Japanese research institution, JAMSTEC. Images relayed from cameras on the vehicle back to the surface revealed planktonic creatures throughout the water column and a diverse assortment of life on the sea floor - sea cucumbers, brittlestars, small translucent shrimp, fish, molluscs and much more. Kaiko is a wonderfully capable machine, but sadly, no nation now has the capability of delivering people seven miles down - and returning them safely to the surface.

Why bother

Sceptics may ask, why bother to go at all?

Mountain climbers justify their passion for ascending to the highest places above sea level, the top of Mount Everest, with a simple "because it's there." For some, the same rationale may work for the deep sea, that is, the lure of the unknown, the need to discover what no one has seen before, to venture where no one else has dared go.

Others have found down-to-earth practical motives in the need to retrieve things lost in the sea - search, salvage and especially submarine rescue. In the 1960's, the loss in deep water of U. S. Navy submarines Thresher and later, Scorpion, provoked intense interest in deep-diving capability. The loss of a live hydrogen bomb in more than 1,000 feet of water off the coast of Palomares, Spain, was a not-so-gentle "wake-up call" highlighting the importance of deep ocean access.

In the decade of the 1960's, another dramatic event fired interest in going deep. In a highly secret project involving the use of a large ship, Glomar Explorer, parts of a Soviet submarine were recovered - under the guise of a deep sea mining operation. Prior to that time, it was known that in some parts of the deep sea, potato-sized nodules rich in iron, manganese, copper and other metals were extremely abundant, but recovery seemed hopelessly impractical. The apparent interest of a large commercial firm in mining the nodules sparked considerable activity among many companies that did not want to miss out on what appeared to be a realistic and possibly lucrative enterprise.

Rich deposits

In 1970, drafters of the United Nations Law of the Sea Treaty proposed that the deep sea bed in the areas beyond national jurisdiction - then typically three to twelve miles - be held in trust by the United Nations as the "Common Heritage of Mankind," and that its resources be developed by a United Nations enterprise. The plan was not acceptable to many nations, but a compromise was reached with respect to deep sea mining, with certain concessions to nations that had already made an investment in exploration.

In the years that followed, as nations claimed the area offshore to 200 miles to be their Exclusive Economic Zone (EEZ), deep water areas became part of the equation for many, especially certain small island nations. Within 200 miles of the Cook Islands in the South Pacific, for example, there are hundreds of square miles of ocean bottom in 15,000 to 20,000 feet of water and on their muddy surface rests some of the most dense accumulations of manganese nodules known.

Since then, interest in deep sea mining has waxed and waned repeatedly, largely linked to economic feasibility - or lack of it. Attention has also extended to the potential for mining crusts of metal-bearing ores created in association with hydrothermal vents and hot seeps in the deep sea. Discovery of rich deposits in deep water within the EEZ of Papua New Guinea has attracted commercial mining operations, and other areas are being targeted for exploitation.

Among the most compelling economic reasons for gaining access to the deep sea is that offshore oil and gas extraction has been moving steadily deeper. Once limited to a few hundred feet, operations are now underway in thousands of feet underwater, far offshore, using sophisticated systems that rival technology developed for living and working in space.

New kingdom

New technology has also provided effective ways to find and extract wildlife from the sea. Acoustic techniques developed to identify and track submarines have been adapted to detect aggregations of fish that have heretofore escaped notice, and new lightweight, strong, and durable materials for nets facilitate their capture - even in thousands of feet of water.

The consequences of exploiting remote parts of the ocean, either for living resources or for minerals, before these areas have been explored, before their overall significance to planetary functions has been considered, is beginning to arouse concern. Sizing up the assets, whether for environmental or economic values, has become an increasingly compelling reason to explore the deep sea. whale© Kevin Atkin/Still PicturesMost of what is known about the ocean has been learned since Beebe and Barton first glimpsed creatures living half a mile underwater, half a century ago. Coincident with the development of technology for effective access to the depths, revolutionary new insights have been achieved concerning the existence of entire subsea mountain ranges, of global processes involving the motion of continents and of the deep sea floor. Just as revolutionary have been biological discoveries - previously unknown communities with a life-style based on chemosynthesis, an awakening awareness of the enormous diversity of life throughout all of the sea, the discovery of a new kingdom of microbes that provides clues concerning the origin of life itself - and much more.

Largest habitat

Meanwhile, vast perturbations, caused by increasing human disruption to natural systems worldwide, have given a sense of urgency to an already lively interest in planetary processes. As a new millennium approaches, concerns are being widely voiced about the consequences of global warming, the effects of El Niño, the sharp decline of once abundant ocean wildlife, the quality of air, water, and life in general. There is a growing awareness of the need to understand how the Earth's overall physical, chemical and biological systems interact. It seems reasonable that exploration of deep sea - the largest habitat on Earth - should be taken into account as a natural extension of the rest of the planet. This is the time to "put it all together," with nothing less than the future of mankind at stake.

Dr Sylvia A. Earle is an oceanographer and founder of Deep Ocean Exploration Research (DOER) and holder of numerous awards for her work in marine science and conservation, including the 1997 Bal de la Mer Foundation's Sea Keeper Award. Dr Earle has led more than 50 underwater expeditions and holds a depth record for solo diving (1000 metres). She is author of numerous publications concerning marine science, including Sea Change (published by Constable, London,1995, £18.95).