Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 8
Exploration of the Seas: Interim Report inventories of natural resources, improving navigation and commerce, and identifying important habitats. The discovery of new resources may boost the U.S. economy. New life forms, such as those found within the hydrothermal vents, may provide us with new bioproducts with applications in human health, agriculture, and industry. These discoveries may also help us generate new hypotheses about the beginning of life on Earth, and the potential for life on other planets. PRIORITY AREAS FOR OCEAN EXPLORATION Ocean exploration is a vast field and the possibilities of discovery are seemingly endless. However, some key areas for exploration have emerged as particularly valuable. Here we highlight topics that might be suitable as preliminary exploration programs. This list is not intended to be exclusive, nor prioritized, but should provide the reader with an idea of the sorts of programs the Committee feels the international community might be willing and ready to support, with foreseeable outcomes that would serve to enhance greatly our ability to study these facets of the ocean in more detail. Other targeted areas for international cooperation in ocean exploration will undoubtedly emerge as the proposed exploration initiative gets underway. In evaluating the potential of possible topics for exploration, the Committee weighed the following characteristics: international interest; current state of knowledge; characteristics of a habitat, region, or discipline that suggest significant, new discoveries will emerge; and possible benefits to humankind. Some of the promising scientific areas identified as having broad international interest include: marine biodiversity, the polar oceans, marine archaeology, deep water and its role in climate change, and exploring the ocean through time. Studies in these areas will reveal additional insights into living and non-living resources (e.g., fisheries, bioproducts, energy resources, mineral deposits), human history, and the changes in physical, chemical, and biological properties of the ocean and seafloor that affect our environment and climate. Marine Biodiversity Only a fraction of the world’s marine species have been discovered and even fewer have been scientifically identified and named (Winston, 1992; World Resources Institute, 2001). New species are discovered on virtually every expedition that seeks to uncover them, including corals, fishes, plants, and even microorganisms like Archaea, which represent an entirely new domain of life (Norse, 1993). If little is known about the overall biodiversity in the ocean, even less is known about the abundance of organisms, their ecological roles, how food webs are structured, and how vast areas of the ocean are connected through biological interactions. Since we now know that even remote areas of the ocean contain detectable levels of human contaminants (Group of Experts on the Scientific Aspects of Marine Environmental Protection, 2001), we can surmise, but not yet quantify, the extent to which humans directly and indirectly affect marine
OCR for page 9
Exploration of the Seas: Interim Report ecosystem health and productivity. Ultimately, better understanding of marine systems and our impacts on those systems will enable us to more wisely utilize the vast resources the ocean has to offer, and help us safeguard the wondrous web of life the ocean supports. A few particularly exciting areas for exploration into marine biodiversity include the following: The microbial ocean. Although we know that thousands of organisms may live in a single drop of seawater, the vast majority of these organisms cannot be cultured in the lab. New genetic tools are allowing researchers to unlock the secrets of their identities, taxonomy, spatial diversity, and role in the ecosystem using their genetic code. The ocean’s extreme environments. The ocean floor harbors some of Earth’s most extreme environments, with crushingly high pressures, temperatures from below freezing to almost boiling, and surprising chemical compositions. Up until a quarter of a century ago, the deep sea was viewed as a hostile environment with a limited supply of food descending from surface waters and low biomass. The discovery in 1977 of luxuriant ecosystems associated with deep-sea hydrothermal vents dramatically altered this view. These ecosystems exist in the deep sea and are not dependent on organic matter sinking from the sunlit surface ocean. Rather, the micro-organisms at the base of this ecosystem support it through extracting energy from chemicals in the high-temperature fluids at the vents. Equally sensational discoveries may be waiting in other unusual ocean environments including other planets and moons. The subsurface biosphere. In 1991, scientists working on the mid-ocean ridge in the eastern Pacific witnessed a “snow blizzard” of microbes and microbial debris being spewed out of the seafloor (Haymon et al., 1993). The material rose more than 100 feet above the ocean bottom and settled into a thin, white layer on the seafloor. Microbes have also been detected in cores recovered by the Ocean Drilling Program (ODP) down to depths of several hundred meters, and have been demonstrated to play an important role in crustal alteration. Coral reefs (Figure 3). Although coral reefs are spectacularly rich in species, complex in their functioning, and high in recreational, fisheries, and socio-economic values, no comprehensive global map of the reefs exists. Coral reef biologists and conservationists often must rely on naval charts and centuries-old ship logs to guess where reefs lie. Corals have been identified in cold water regions, such as the northeast Atlantic, exemplifying how little is known of their distribution, condition, or relative health. Many of the world’s coral reefs lie within the territorial waters of nations struggling to maintain environmental quality in the face of economic pressures. An international coral reef exploration program is needed to locate, understand, and protect these fragile ecosystems.
OCR for page 10
Exploration of the Seas: Interim Report Figure 3. The diversity of fish and other reef organisms rival tropical rainforests. Seamounts. These underwater mountains are another rich and functionally important marine ecosystem ripe for discovery. While the major seamounts are known from topographic mapping, many small but ecologically critical seamounts remain unknown. A recent survey of fish aggregation and spawning areas of the western Pacific has revealed an extensive array of seamounts in that portion of the world ocean, providing a good foundation for future efforts to choose sites for marine protected areas that will serve to maintain fisheries production and safeguard biodiversity. Continental shelves. The organisms that live within the sediments on continental shelves, especially temperate banks and intertidal areas, include numbers of species rivaling those of insects found in tropical forests. These sediment-dwelling organisms are thought to play an important role in linking the seafloor ecosystem with the water column above, and ultimately in supporting the marine food web. Unfortunately, the seafloor in many of these coastal areas has been degraded or destroyed through uncontrolled trawling, dredging (National Research Council, 2002), and coastal construction. Ocean exploration can take scientists to areas that are still relatively pristine to discover how these systems function and better understand the effects of human intervention. The Polar Oceans The Southern Ocean is the least explored of the world’s ocean. There are few observations during the austral winter and, even during the austral summer, there are regions beneath the floating ice shelves that remain inaccessible to ships. Highly specialized, but mostly unsampled, biota occupy the extreme habitats under the ice. The Southern Ocean is highly productive biologically, containing large stocks of living resources that require understanding for effective protection and management (Figure 4).
OCR for page 11
Exploration of the Seas: Interim Report Figure 4. Jellyfish floating under Arctic ice. The waters under the floating ice are extremely cold and dense, contributing to the formation of the Antarctic Bottom Water with special physical and chemical properties. Deep water formation is one of the most important oceanographic processes on Earth, and a driving mechanism that initiates deep-reaching convection and global-scale thermohaline circulation. The Southern Ocean is one of the regions this process is known to occur. Vast areas of the Southern Ocean seafloor remain unmapped, yet it contains records of the disintegration of the Gondwana supercontinent and the opening of the Drake Passage. Many believe the latter to be one of the key events leading to the present global climate. Many important aspects of the Southern Ocean have not been properly explored because of the lack of suitable technology. An ocean exploration program could foster the development of a new generation of specialized AUVs and other types of probes that can be lowered through holes drilled through hundreds of meters of ice. The Arctic Ocean is flanked by broad continental margins likely to contain new living and non-living resources. Because of its ice cover, remoteness, and harsh weather, it has been the target of numerous heroic, and in earlier times often tragic, visits by explorers. This region remains a high priority for exploration because of its influence on the habitability of northern North America and Eurasia. The tectonic history of the western Arctic Ocean is basically unknown. The ultra-slow spreading of the Arctic midocean ridges gives rise to spectacular topographic relief and a complex crustal architecture. Volcanic activity is markedly reduced, with the result that major portions of the ridge are composed of rocks from the mantle. Virtually nothing is known about this mechanism of building new crust in this extreme environment. The present isolation of the Arctic Ocean and its separation from all other ridge systems also raises fundamental questions about the evolution and ecology of Arctic vent fauna. Hydrographic barriers and geologic features enclosing the Arctic Ocean spreading centers pose a significant barrier to dispersal of vent species. The recent recovery of a few specimens of vent fauna while dredging along the Gakkel Ridge in the Arctic Ocean confirms the existence of vent ecosystems in this region. Indeed, these isolated ecosystems may hold keys to the evolution of life at hydrothermal vents (Figure 5).
OCR for page 12
Exploration of the Seas: Interim Report Figure 5. Mussels, worms, and a spider crab at a hydrocarbon seep community. The Arctic sea ice cover existed millions of years ago. Properties of the “warm” Arctic Ocean prior to the sea ice cover are unknown and can only be resolved by applying new technology to sample the history of oceanic sediments beneath the ice. These sediments may illustrate past examples of a scenario that could develop again due to global warming. Exploration of the polar oceans will be most effectively undertaken through a large, multi-platform ocean exploration program. Expense and logistical support necessitate strong international collaboration, for which there is growing support. Because our current understanding of the polar oceans is fragmented and spatially limited they are a strong candidate for program initiation. Marine Archaeology One cannot imagine a history of our globe without watercraft. From the primitive floats or rafts that carried the first people to Australia 50,000 years ago to the giant oil tankers and aircraft carriers of today, boats and ships have allowed the discovery, colonization, supply, and defense of entire continents. The study of the history of ships is therefore important in itself. But just as important, virtually everything ever made by humans, from tiny obsidian blades and bits of jewelry to the huge marble elements of entire temples and churches, has been transported at one time or another over water. Thus, the exploration of shipwrecks of all periods will write definitive histories of weapons, tools and other utensils, glass, ceramics, games, sculpture, weights and measures, metallurgy, and, especially in later times, instruments and machines of all types (Figure 6). Equally important, shipwrecks can teach us about economic history. Marine
OCR for page 13
Exploration of the Seas: Interim Report archaeology can also uncover inundated coastal habitation sites that teach us about our early ancestors. Exploration of the Earth’s blue museum will rewrite whole chapters in history and could reveal the most startling archaeological discoveries of the 21st century. Figure 6. Carolyn visits a medieval shipwreck whose cargo consisted of millstones (used with permission from Tufan Turanli, Institute of Nautical Archaeology). Deep Water and Its Role in Climate Change The ocean and the atmosphere store heat derived from the sun and redistribute that heat from the Equator toward the poles. The ocean’s mass may slow the transitions from one climate regime to another, as the slow overturning of the deep-ocean limits heat absorption and release at the ocean surface. On the other hand, there is also evidence that a reduction in surface salinity due to melting polar ice in the North Atlantic Ocean could increase the speed of climatic transitions. Suppression of the flow of cold, salty, dense surface water into the deep ocean (the North Atlantic Deep Water [NADW] formation) could alter the global-scale thermohaline circulation, resulting in less intense surface currents and less poleward transport of heat. The formation of NADW has other effects on global climate as well because it carries greenhouse gases to the deep ocean, out of contact with the atmosphere for hundreds of years. Finally, extraction of fresh water from the ocean via evaporation, which produces the high salinity of the NADW, provides water for the global hydrological cycle. A better understanding of the global climate system requires a much more sophisticated understanding of the thermohaline circulation, its vulnerability to change, and the processes that govern water mass formation rates (National Research Council, 1994, 2001). Retrospective exploration of deep ocean water temperatures over time may provide new insights to trends in global climate. Surface water temperature can be measured with limited accuracy but high resolution, from space. New systems like the Array for Real-Time Geostrophic Oceanography can measure the temperature of the ocean to depths of 1,000 m with an average of 300 km resolution. Ocean thermometry using acoustic methods can resolve deep
Representative terms from entire chapter: