Foreword
By Sylvia Earle, PhD
Ambassador for the World's Oceans and National Geographic Society Explorer-in-Residence
The only other place comparable to these marvelous nether regions, must surely be naked space itself ... where the blackness of space, the shining planets, suns and stars must really be closely akin to the world of life as it appears to the eyes of an awed human being, in the open sea half a mile down.
- William Beebe, HALF MILE DOWN
Until recently, many had the impression that the diversity of life in the sea was much lower than the complexity and richness of life on the land, especially tropical rainforests and temperate woodlands. It is easy to understand how this misconception arose -- largely because of the immense diversity of insects, especially beetles, altogether comprising about half of all the species thus far named that live on land. More important, humans are terrestrial, air-breathing creatures able to travel everywhere over the face of the land, even to the highest mountains, driest deserts and coldest polar regions, and thus are familiar with the various creatures great and small that live on land. Accessing the sea is more challenging.
Although the ocean comprises 99 percent of the biosphere and only 5 percent of that has been seen -- let alone explored -- it is little wonder that misconceptions have developed about the true nature of life on Earth. Fortunately, new technologies enhance our ability to find and document life from sunlit reefs to the deepest, darkest seas -- and the results are magnificently portrayed in this volume. Great challenges remain, but those involved with the Census of Marine Life have made giant strides in evaluating the nature of the past, present and future of life in the sea, and thus of life on Earth.
Far from being monotonous empty space, as some have long believed, the ocean everywhere is alive. In a single swirl of salt water, a plankton-feeding whale shark may swallow the larval or adult stages of 15 or more phyla (or divisions) of animals -- as many as all terrestrial phyla of animals combined. That single gulp also will likely contain a dozen or so phyla of Protists, including minute photosynthetic forms that do much of the heavy lifting in terms of generating oxygen and transforming water combined with carbon dioxide into food. Then there are the microbes. Thousands of new species are being discovered in nearly every sample of seawater being analyzed with current techniques, from bacteria to members of the kingdom Archeae, discovered late in the 20th century. It is not just the small creatures that have gone unnoticed. New families as well as new genera and species of coral, sponges, echinoderms, annelids and others are turning up on nearly every dive below a thousand feet or so. When biologist-diver-explorer Richard Pyle ventures into the almost-light almost-dark region of the sea known as "the twilight zone," he finds new fish species at the rate of about seven per hour of observation.
Given the magnitude of new discoveries, and the vast areas of ocean yet to be explored, it is clear that the unknown species of marine life far exceed the 250,000 or so now accounted for. So, how many kinds of plants, animals, microbes and other forms of life are in the sea? Estimates range from a million to one hundred million, making the goal of the Census of Marine Life -- taking stock of the diversity of life in the sea -- one of the most ambitious undertakings in the history of humankind. In effect, it means exploring, analyzing and making some kind of systematic sense of most of life on Earth. It is a daunting but worthy goal, vital, in fact, if humankind is to achieve an understanding of the natural systems that make life on Earth possible.
The importance of the Census is made urgent because at the same time that more is being learned about the diversity of life in the sea than during all preceding history, more is being lost. Jacques Cousteau's personal perspective -- from pioneering dives in the 1950s in pristine seas to an era a few decades later of "paradise lost" -- inspired the world to take notice, and to act. It is not just the obvious decline of marine mammals, seabirds, fish and other wildlife owing to deliberate or incidental killing of ocean wildlife for food and products, although some, such as the Caribbean monk seal, last seen in 1952, have been eliminated thus. Numerous creatures have a narrow home range, and when their habitat is destroyed, they are lost as well. Species endemic to specific coral reefs, to individual seamounts and to highly specialized associations, such as barnacles that live only on one kind of turtle or whale or crab, are especially vulnerable. Changes in ocean temperature and chemistry through human actions, now including acidification, are causing comprehensive shifts of geological magnitude on the global environment, and in turn on the species that comprise the countless bits and pieces that make up the whole.
No one can be certain of what the consequences will be of the damage that humans have wrought to the underpinnings of what has made Earth a hospitable place for our species. No one will ever know how many kinds of creatures have been or will be destroyed as a consequence of these changes. But it is clear that maintaining the diversity of life, from individual species to large ecosystems, is the key to resilience, to holding the planet steady through the trauma of rapid climate shifts and the other unprecedented changes that are upon us. At present, about 12 percent of the land is invested in national parks and preserves, worldwide, protecting the diversity of terrestrial and freshwater species and systems while but a fraction of 1 percent of the ocean is similarly safeguarded.
In an exceptional model of international cooperation targeting a singular goal, more than two thousand Census of Marine Life scientists have delved into past records, dived into modern oceans, and extrapolated future scenarios. Together, they have yielded a priceless gift: enhanced understanding of the nature of life in the sea and its importance concerning all that humans care about -- health, the economy, security and, most important, a planet that works in our favor. A distillation of their Herculean decade of exploration is contained here, magnificently illustrated and eloquently written by the authors and contributors.
Some will treasure World Ocean Census as a valuable reference, others as a place to find white-knuckle adventures. The images alone will cause many to re-evaluate their concepts of what astonishing forms are embraced within the bounds of what constitutes an eye, a heart, a body of living tissue. The underlying similarities shared by all living things -- humans very much included -- shine through, while maintaining wonder at the infinite capacity for diversity: from the broad divisions of life to the individual speckles and shapes that distinguish each sardine, salp and starfish from every other of its kind. Above all, the breakthroughs in knowledge gained, and awareness of the magnitude of what remains to be discovered, inspire hope that the greatest era of ocean exploration -- and ocean care -- will now begin.
Introduction
Unlocking the Mystery of What Lives Below the Surface of the Global Sea
For thousands of years, indigenous traditions have described the ocean as the mythological birth place of life on Earth, a mysterious place filled with life-sustaining forces. In an ancient myth of the Yurok Indians of California, two great beings, Thunder and Earthquake, worked together to create the ocean and fill it with water. The animals came to live there because of its beauty. Their story speaks of seals that came to the newly formed ocean "as if they were thrown in by handfuls." Looking upon the ocean basin they had made -- vast, deep and full of water -- Earthquake and Thunder were satisfied that their job was done. The ocean was large enough to provide sustenance for all of Earth's creatures.
It is not surprising that the ocean has long fascinated humankind. Earth is the only planet known to have liquid water at the surface, and very little of the ocean has been scientifically investigated. However, there are accepted theories about its formation and composition and even some consensus about how it works, despite the lack of comprehensive data. Most scientists believe that the first, shallow oceans formed between 4 billion and 3.5 billion years ago. As the molten-hot newly forming crust of Earth cooled, it gave off great volumes of steam and water vapor, which in turned caused clouds to form and rain to fall. The rain carried salts and other elements from Earth's cooling surface into shallow depressions or basins in the crust. Before an ocean could form, the temperature had to fall to below 100 degree Celsius, the boiling point of water, so that the liquid could remain stable.
Over time and through complex geological processes, cooled crustal plates formed over the more molten interior mantle, and the ocean basins deepened. As the plates slowly circulated over the molten mantle, they drew together and were pulled apart over and over again, eventually forming Earth's first supercontinent -- a single landmass consisting of all the modern continents -- Vaalbara. Believed to have formed between 3.6 billion and 3.3 billion years ago, it was surrounded by a vast sea. As this early supercontinent broke apart and the crustal plates continued their journey, the configuration of the ocean changed as well. As we know it today, the world's ocean accounts for roughly 71 percent of our planet's surface and 99 percent of its inhabitable volume; its average depth is approximately 3.8 kilometers (close to 2.4 miles).
Scientists are still trying to unravel one of the greatest mysteries of Earth: when did "life" first appear and how did it happen? The scientific community has been debating the timing and mechanisms of the origin of life for many years. However, most agree that the earliest life-forms evolved in the ocean, most likely as primitive, one-celled forms that appeared about 3 billion years ago. This primitive life was all that existed for approximately the next 2 billion years. Then a profusion of multicellular life exploded, in incredibly complex forms, and began to fill the oceans. As some marine species became able to live on land, new and increasingly complex forms of life began to appear all over the planet.
Many of the microscopic life-forms, or microbes, that currently live in the ocean may be similar to Earth's early life, and their abundance is extraordinary. Microbiologist Mitch Sogin and his team at the Marine Biological Laboratory at Woods Hole, Massachusetts, discovered more than 20,000 kinds of microbes in a single liter (about 1 quart) of seawater; previous research had led them to expect only 1,000 to 3,000. "Peering through a laboratory microscope into a drop of seawater is like looking at the stars on a clear night," says Census marine microbiologist Victor Gallardo, of Universidad de Concepción, Chile. "New DNA tag-sequencing technology increases resolution much like the Hubble Telescope did for space. We can see marine microbial diversity to which we were blind before. These rare ancient organisms are likely to prove a key part of nature's history and strategy."
The current average salt content of this cradle of life is approximately 35 parts to 1,000 parts of ocean water. Some scientists estimate that the oceans contain as much as 50 quadrillion (50 million billion) tons of dissolved solids, mainly dissolved salts such as sodium chloride. If the salt in the sea were removed and spread evenly over the earth's land surface, it would form a layer more than 150 meters (500 feet) thick, about the height of a 40-story office building! Salts become concentrated in the sea because the sun's heat evaporates almost pure water from the ocean surface, leaving the salts and salty water behind. This process is part of a continual exchange of water between the earth and the atmosphere called the hydrologic cycle.
The salinity of ocean water varies. It is affected by such factors as melting ice, inflow of river water, evaporation, rain, snowfall, winds, wave motion and ocean currents that cause horizontal and vertical mixing of the saltwater. Small changes in salinity can greatly affect ocean life. Some organisms can tolerate wide swings in salinity, while others, such as many corals, can tolerate only narrow salinity ranges. The saltiest water occurs in the Red Sea and the Persian Gulf, where rates of evaporation are very high. Of the major ocean basins, the North Atlantic is the saltiest. Low salinities occur in polar seas, where the salt water is diluted by melting ice and frequent precipitation.
Salinity is not the only variable that affects marine life. Other parameters include temperature, available nutrients, currents, winds, storms and ice. To fully comprehend how species survive in the ocean, it is important to understand how the ocean works. Important unanswered questions remain about the interdependency of oceanic parameters, such as how winds affect currents, how currents affect the temperature and flow of nutrients, and how nutrients control productivity. The limits to our current understanding can be overcome only by further ocean exploration -- by initiatives such as the Census of Marine Life that are investigating the biology of the global ocean and how its physical properties affect its inhabitants.
Launched in 2000 with the goal of producing the first-ever ocean census by 2010, the Census of Marine Life brought together 2,000 explorers from 82 nations to answer three important questions: What once lived in the global ocean? What is living there now? What will live there in the future? So little is known about what lives below the surface in the global ocean that the Census is much like a space program; it too has inherent challenges and dangers, and likewise generates excitement about exploring the unknown. To reach the depths of the global ocean -- as deep as 11 kilometers (7 miles) below the surface -- requires equipment that is just as sophisticated as the technology used to explore the outer reaches of the universe. Unlike space programs, however, underwater technology has only recently become advanced enough to allow explorers a fish's-eye view of what lives in the deepest, darkest, coldest reaches of the ocean.
Census of Marine Life scientists have been working at the cutting edge, using new technology to explore previously unreachable places and capturing images of the incredible life-forms -- everything from blind lobsters to worms that live without oxygen -- that exist at the bottom of the sea. This book provides an inside look at their many adventures, reveals their findings and shares the fabulous images they have captured as they unlock the mystery of what lives below the surface in the wondrous global sea.
