1.
Submarine volcano
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Submarine volcanoes are underwater vents or fissures in the Earths surface from which magma can erupt. A large number of volcanoes are located near areas of tectonic plate movement. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the output on Earth. Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in water. The total number of volcanoes is estimated to be over 1 million. Hydrothermal vents, sites of abundant biological activity, are found near submarine volcanoes. The presence of water can alter the characteristics of a volcanic eruption. For instance, water causes magma to cool and solidify much more quickly than in a terrestrial eruption, the lava formed by submarine volcanoes is quite different from terrestrial lava. Upon contact with water, a solid crust forms around the lava, advancing lava flows into this crust, forming what is known as pillow lava. Below ocean depths of about 2200 m, where the pressure exceeds the pressure of, it can no longer boil. Without boiling sounds, deep-sea volcanoes can be difficult to detect at great distances using hydrophones, the values of the critical temperature and pressure increase in solutions of salts, which are normally present in the seawater. The actual composition of aqueous solution in the vicinity of hot basalt, One estimation is that the critical point is 407 °C and 29.9 MPa, while the solution composition corresponds to that of approximately 3. 2% of NaCl. Scientists still have much to learn about the location and activity of underwater volcanoes, the Kolumbo underwater volcano in the Aegean Sea was discovered in 1650 when it burst from the sea and erupted, killing 70 people on the nearby island of Santorini. More recently, NOAAs Office of Ocean Exploration has funded exploration of submarine volcanoes, using Remote Operated Vehicles, scientists studied underwater eruptions, ponds of molten sulfur, black smoker chimneys and even marine life adapted to this deep, hot environment. Many submarine volcanoes are seamounts, typically extinct volcanoes that rise abruptly from a seafloor of 1,000 -4,000 meters depth and they are defined by oceanographers as independent features that rise to at least 1,000 meters above the seafloor. The peaks are found hundreds to thousands of meters below the surface. An estimated 30,000 seamounts occur across the globe, with only a few having been studied, however, some seamounts are also unusual. There are two types of eruptions, One is created by the slow release and bursting of large lava bubbles
2.
Marine habitats
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The marine environment supplies many kinds of habitats that support marine life. Marine life depends in some way on the saltwater that is in the sea, a habitat is an ecological or environmental area inhabited by one or more living species. Marine habitats can be divided into coastal and open ocean habitats, coastal habitats are found in the area that extends from as far as the tide comes in on the shoreline out to the edge of the continental shelf. Most marine life is found in habitats, even though the shelf area occupies only seven percent of the total ocean area. Open ocean habitats are found in the ocean beyond the edge of the continental shelf. Alternatively, marine habitats can be divided into pelagic and demersal zones, pelagic habitats are found near the surface or in the open water column, away from the bottom of the ocean. Demersal habitats are near or on the bottom of the ocean, an organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, a living in a demersal habitat is said to be a demersal organism. Pelagic habitats are shifting and ephemeral, depending on what ocean currents are doing. Marine habitats can be modified by their inhabitants, some marine organisms, like corals, kelp, mangroves and seagrasses, are ecosystem engineers which reshape the marine environment to the point where they create further habitat for other organisms. In contrast to terrestrial habitats, marine habitats are shifting and ephemeral, swimming organisms find areas by the edge of a continental shelf a good habitat, but only while upwellings bring nutrient rich water to the surface. Shellfish find habitat on sandy beaches, but storms, tides, the presence of seawater is common to all marine habitats. Beyond that many other things determine whether a marine area makes a good habitat, the ocean occupies 71 percent of the world surface, averaging nearly four kilometres in depth. There are five major oceans, of which the Pacific Ocean is nearly as large as the rest put together, coastlines fringe the land for nearly 380,000 kilometres. Marine habitats can be divided into pelagic and demersal habitats. Pelagic habitats are the habitats of the water column, away from the bottom of the ocean. Demersal habitats are the habitats that are near or on the bottom of the ocean, an organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, a living in a demersal habitat is said to be a demersal organism
3.
Davidson Seamount
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Davidson Seamount is a seamount located off the coast of Central California,80 mi southwest of Monterey and 75 mi west of San Simeon. At 26 mi long and 8 mi wide, it is one of the largest known seamounts in the world, from base to crest, the seamount is 7,480 ft tall, yet its summit is still 4,101 ft below the sea surface. The seamount is biologically diverse, with 237 species and 27 types of deep-sea coral having been identified, discovered during the mapping of Californias coast in 1933, Davidson Seamount is named after geographer George Davidson of the U. S. National Geodetic Survey. Studied only sparsely for decades, NOAA expeditions to the seamount in 2002 and 2006 cast light upon its unique deep-sea coral ecosystem, Davidson Seamount is populated by a dense population of large, ancient corals, some of which are over 100 years of age. The data gathered during the studies fueled the making of Davidson Seamount into a part of the Monterey Bay National Marine Sanctuary in 2009, a seamount such as Davidson is an underwater volcano, this one rises over 3,280 ft above the surrounding ocean floor. Although there are over 30,000 seamounts in the Pacific Ocean alone, the aqueous environment of the seamount means that it behaves differently from volcanoes on land. Its surface is composed mostly of blocky lava flows, although some pillow lava, the summit is composed of layered deposits of volcanic ash and pyroclastic material. These rocks indicate mildly explosive eruptions of gas-rich lava near the summit of the volcano, the base of Davidson is probably buried in a deep layer of muds. At 26 mi long and 8 mi wide, Davidson Seamount is impressively large, if it were on land, it would dominate the landscape in a way similar to how Mount Shasta dominates the horizon of northern California. Put in perspective, the size of the seamount is enough to fill Monterey Bay from the Santa Cruz boardwalk to Montereys Fishermens Wharf and this group is morphologically unique, and very similar to one another. All the seamounts in the group are complex northeast-southwest trending structures, the ridges constructed run parallel to an ancient spreading center which has since been replaced in its role by the San Andreas Fault system. They are unique in this origin, as they are formed from the remnants of an old ocean-ridge spreading center, a series of knobs are aligned with the ridges, however the distinctive summit crater, evident in many oceanic volcanoes, is absent. This lack of a collapse crater suggests that magma was never stored in a chamber within the structure, analysis of argon–argon dating studies indicate that Davidson formed between 9 and 15 million years ago,5 to 12 million years after the formation of the overlaying oceanic crust. Studies have indicated that a seamount functions as an oasis of life, with a species count. However, it is believed that they provide a refuge for species that have difficulty surviving elsewhere. There are reasons that seamounts are biologically important and they rise high in the water column, creating complex current patterns that support life on, around, and above the seamount. The surface of the seamount also provides a substrate upon which organisms can attach themselves and this in turn supports the species that feed on them, in turn supporting the whole ecological food web. Scientists have found that often provide a habitat for endemic species that are not found anywhere else
4.
Littoral zone
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The littoral zone is the part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the water mark. It always includes this intertidal zone and is used to mean the same as the intertidal zone. However, the meaning of littoral zone can extend well beyond the intertidal zone, what is regarded as the full extent of the littoral zone, and the way the littoral zone is divided into subregions, varies in different contexts. The use of the term varies from one part of the world to another. For example, military commanders speak of the littoral in ways that are different from marine biologists. The adjacency of water gives a number of characteristics to littoral regions. The erosive power of water results in particular types of landforms, such as sand dunes, the natural movement of the littoral along the coast is called the littoral drift. Biologically, the availability of water enables a greater variety of plant and animal life. In addition, the local humidity due to evaporation usually creates a microclimate supporting unique types of organisms. The word littoral is used both as a noun and an adjective and it derives from the Latin noun litus, litoris, meaning shore. In oceanography and marine biology, the idea of the zone is extended roughly to the edge of the continental shelf. Starting from the shoreline, the zone begins at the spray region just above the high tide mark. From here, it moves to the region between the high and low water marks, and then out as far as the edge of the continental shelf. These three subregions are called, in order, the zone, the eulittoral zone and the sublittoral zone. The supralittoral zone is the area above the high tide line that is regularly splashed. Seawater penetrates these elevated areas only during storms with high tides, organisms here must cope also with exposure to fresh water from rain, cold, heat and predation by land animals and seabirds. At the top of this area, patches of dark lichens can appear as crusts on rocks, some types of periwinkles, Neritidae and detritus feeding Isopoda commonly inhabit the lower supralittoral
5.
Intertidal zone
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The intertidal zone, also known as the foreshore and seashore and sometimes referred to as the littoral zone, is the area that is above water at low tide and under water at high tide. This area can include different types of habitats, with many types of animals, such as starfish, sea urchins. The well-known area also includes rocky cliffs, sandy beaches. The area can be a strip, as in Pacific islands that have only a narrow tidal range. Organisms in the zone are adapted to an environment of harsh extremes. The intertidal zone is home to many several species from different taxa including Porifera, Annelids, Coelenterates, Mollusks, crustaceans, Arthropods. Water is available regularly with the tides but varies from fresh with rain to highly saline, wave splash can dislodge residents from the littoral zone. With the intertidal zones high exposure to the sun, the range can be anything from very hot with full sun to near freezing in colder climates. Some microclimates in the zone are ameliorated by local features. Adaptation in the littoral zone allows the use of nutrients supplied in high volume on a basis from the sea. Edges of habitats, in this land and sea, are themselves often significant ecologies. Along most shores, the zone can be clearly separated into the following subzones, high tide zone, middle tide zone. The intertidal zone is one of a number of biomes or habitats, including estuaries, neritic, surface. Marine biologists divide the region into three zones, based on the overall average exposure of the zone. The low intertidal zone, which borders on the shallow subtidal zone, is exposed to air at the lowest of low tides and is primarily marine in character. The mid intertidal zone is exposed and submerged by average tides. The high intertidal zone is covered by the highest of the high tides. The high intertidal zone borders on the splash zone, on shores exposed to heavy wave action, the intertidal zone will be influenced by waves, as the spray from breaking waves will extend the intertidal zone
6.
Estuary
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An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a zone between river environments and maritime environments. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The inflows of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea began to rise about 10. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns, the banks of many estuaries are amongst the most heavily populated areas of the world, with about 60% of the worlds population living along estuaries and the coast. The word estuary is derived from the Latin word aestuarium meaning tidal inlet of the sea, there have been many definitions proposed to describe an estuary. However, this definition excludes a number of water bodies such as coastal lagoons. This broad definition also includes fjords, lagoons, river mouths, an estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides. The sea water entering the estuary is diluted by the water flowing from rivers. The pattern of dilution varies between different estuaries and depends on the volume of water, the tidal range. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border, the width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m, examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, and Delaware Bay along the Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast. They are relatively common in tropical and subtropical locations and these estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches partially encloses the estuary, with only narrow inlets allowing contact with the ocean waters, bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments, barrier beaches form in shallow water and are generally parallel to the shoreline, resulting in long, narrow estuaries
7.
Kelp forest
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Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth, smaller areas of anchored kelp are called kelp beds. Kelp forests occur worldwide throughout temperate and polar coastal oceans, in 2007, kelp forests were also discovered in tropical waters near Ecuador. Physically formed by brown macroalgae, kelp forests provide a unique, over the last century, they have been the focus of extensive research, particularly in trophic ecology, and continue to provoke important ideas that are relevant beyond this unique ecosystem. For example, kelp forests can influence coastal oceanographic patterns and provide ecosystem services. However, the influence of humans has often contributed to kelp forest degradation, of particular concern are the effects of overfishing nearshore ecosystems, which can release herbivores from their normal population regulation and result in the overgrazing of kelp and other algae. This can rapidly result in transitions to barren landscapes where relatively few species persist, the term kelp refers to marine algae belonging to the order Laminariales. Though not considered a taxonomically diverse order, kelps are highly diverse structurally and functionally, the most widely recognized species are the giant kelps, although numerous other genera such as Laminaria, Ecklonia, Lessonia, Alaria, and Eisenia are described. Many marine mammals and birds are found, including seals, sea lions, whales, sea otters, gulls, terns, snowy egrets, great blue herons. Frequently considered an ecosystem engineer, kelp provides a physical substrate, in algae, the body of an individual organism is known as a thallus rather than as a plant. The stipe is analogous to a plant stalk, extending vertically from the holdfast, the fronds are leaf- or blade-like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity. In addition, many species have pneumatocysts, or gas-filled bladders. These structures provide the necessary buoyancy for kelp to maintain a position in the water column. The environmental factors necessary for kelp to survive include hard substrate, high nutrients, water flow and turbulence facilitate nutrient assimilation across kelp fronds throughout the water column. Water clarity affects the depth to which sufficient light can be transmitted, in ideal conditions, giant kelp can grow as much as 30-60 cm vertically per day. Some species, such as Nereocystis, are annuals, while others such as Eisenia are perennials, in perennial kelp forests, maximum growth rates occur during upwelling months and die-backs correspond to reduced nutrient availability, shorter photoperiods, and increased storm frequency. Kelps are primarily associated with temperate and arctic waters worldwide, the region with the greatest diversity of kelps is the northeastern Pacific, from north of San Francisco, California, to the Aleutian Islands, Alaska. Although kelp forests are unknown in tropical waters, a few species of Laminaria have been known to occur exclusively in tropical deep waters
8.
Coral reef
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Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals. Coral reefs are built by colonies of tiny animals found in waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups, the polyps belong to a group of animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons which support, most reefs grow best in warm, shallow, clear, sunny and agitated waters. Often called rainforests of the sea, shallow coral reefs form some of the most diverse ecosystems on Earth, paradoxically, coral reefs flourish even though they are surrounded by ocean waters that provide few nutrients. They are most commonly found at depths in tropical waters. Coral reefs deliver ecosystem services to tourism, fisheries and shoreline protection, the annual global economic value of coral reefs is estimated between US$29. 8-375 billion. However, coral reefs are fragile ecosystems, partly because they are sensitive to water temperature. Most of the coral reefs we can see today were formed after the last glacial period when melting ice caused the sea level to rise and this means that most modern coral reefs are less than 10,000 years old. As communities established themselves on the shelves, the reefs grew upwards, Reefs that rose too slowly could become drowned reefs. They are covered by so much water there was insufficient light. Coral reefs are found in the sea away from continental shelves, around oceanic islands. The vast majority of islands are volcanic in origin. The few exceptions have tectonic origins where plate movements have lifted the deep ocean floor on the surface. In 1842 in his first monograph, The Structure and Distribution of Coral Reefs, Charles Darwin set out his theory of the formation of atoll reefs and he theorized uplift and subsidence of the Earths crust under the oceans formed the atolls. Darwin’s theory sets out a sequence of three stages in atoll formation and it starts with a fringing reef forming around an extinct volcanic island as the island and ocean floor subsides. As the subsidence continues, the reef becomes a barrier reef. Darwin predicted that underneath each lagoon would be a bed rock base, where the level of the underlying earth allows, the corals grow around the coast to form what he called fringing reefs, and can eventually grow out from the shore to become a barrier reef
9.
Ocean bank
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An ocean bank, sometimes referred to as a fishing bank or simply bank, is a part of the sea which is shallow compared to its surrounding area, such as a shoal or the top of an underwater hill. Somewhat like continental slopes, ocean banks slopes can upwell as tidal and other flows intercept them, because of this, some large banks, such as Dogger Bank and the Grand Banks of Newfoundland, are among the richest fishing grounds in the world. There are some banks that were reported in the 19th century by navigators, such as Wachusett Reef, ocean banks may be of volcanic nature. Banks may be carbonate or terrigenous, in tropical areas some banks are submerged atolls. As they are not associated with any landmass, banks have no source of sediments. Carbonate banks are typically platforms, rising from the ocean depths, Seamounts, by contrast, are mountains, of volcanic origin, rising from the deep sea, and are steeper, and higher in comparison to the surrounding seabed. Examples of these are Pioneer and Guide Seamounts, west of the Farallon Islands, the Pioneer Seamount has a depth of 1,000 meters, In other cases, parts of a bank may reach above the water surface, thereby forming islands
10.
Continental shelf
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The continental shelf is an underwater landmass which extends from a continent, resulting in an area of relatively shallow water known as a shelf sea. Much of the shelves were exposed during glacial periods and interglacial periods, the shelf surrounding an island is known as an insular shelf. The continental margin, between the shelf and the abyssal plain, comprises a steep continental slope followed by the flatter continental rise. Sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope, extending as far as 500 km from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rises gradient is intermediate between the slope and the shelf, on the order of 0. 5–1°, the largest shelf – the Siberian Shelf in the Arctic Ocean – stretches to 1,500 kilometers in width. The South China Sea lies over another extensive area of shelf, the Sunda Shelf, which joins Borneo, Sumatra. Other familiar bodies of water that overlie continental shelves are the North Sea, the average width of continental shelves is about 80 km. The depth of the shelf also varies, but is limited to water shallower than 150 m. The slope of the shelf is quite low, on the order of 0. 5°, vertical relief is also minimal. Though the continental shelf is treated as a province of the ocean, it is not part of the deep ocean basin proper. Passive continental margins such as most of the Atlantic coasts have wide and shallow shelves, active continental margins have narrow, relatively steep shelves, due to frequent earthquakes that move sediment to the deep sea. The shelf usually ends at a point of increasing slope, the sea floor below the break is the continental slope. Below the slope is the rise, which finally merges into the deep ocean floor. The continental shelf and the slope are part of the continental margin, the shelf area is commonly subdivided into the inner continental shelf, mid continental shelf, and outer continental shelf, each with their specific geomorphology and marine biology. The character of the shelf changes dramatically at the shelf break, with a few exceptions, the shelf break is located at a remarkably uniform depth of roughly 140 m, this is likely a hallmark of past ice ages, when sea level was lower than it is now. The continental slope is steeper than the shelf, the average angle is 3°. The slope is cut with submarine canyons. The physical mechanisms involved in forming these canyons were not well understood until the 1960s, the continental shelves are covered by terrigenous sediments, that is, those derived from erosion of the continents
11.
Neritic zone
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The neritic zone is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately 200 meters in depth. It extends from the low tide mark to the edge of the continental shelf, above the neritic zone lie the intertidal and supralittoral zones, below it the continental slope begins, descending from the continental shelf to the abyssal plain and the pelagic zone. Within the neritic, marine biologists also identify the following, The infralittoral zone is the algal dominated zone to maybe five metres below the low water mark, the circalittoral zone is the region beyond the infralittoral, which is dominated by sessile animals such as oysters. The subtidal zone is the region of the zone which is below the intertidal zone. In particular, the zone in the neritic is much more stable than in the intertidal zone. Corals are also found in the neritic zone, where they are more common than in the intertidal zone as they have less change to deal with. As in marine biology, this typically extends to the edge of the continental shelf
12.
Strait
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A strait is a naturally formed, narrow, typically navigable waterway that connects two larger bodies of water. Most commonly it is a channel of water that lies between two land masses, some straits are not navigable, for example because they are too shallow, or because of an unnavigable reef or archipelago. The terms channel, pass or passage, can be synonymous and used interchangeably with strait, in Scotland firth or kyle are also sometimes used as synonyms for strait. Straits can be important shipping routes, and wars have been fought for control of them, numerous artificial channels, called canals, have been constructed to connect two bodies of water over land, such as the Suez Canal. Although rivers and canals often provide passage between two large lakes or a lake and a sea, and these seem to suit the formal definition of strait, the term strait is typically reserved for much larger, wider features of the marine environment. There are exceptions, with straits being called canals, Pearse Canal, Straits are the converse of isthmuses. That is, while a strait lies between two masses and connects two larger bodies of water, an isthmus lies between two bodies of water and connects two larger land masses. Some straits have the potential to generate significant tidal power using tidal stream turbines, tides are more predictable than wave power or wind power. The Pentland Firth may be capable of generating 10 GW, cook Strait in New Zealand may be capable of generating 5. There may be no suspension of innocent passage through such straits, list of straits Media related to Straits at Wikimedia Commons
13.
Pelagic zone
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Any water in a sea or lake that is neither close to the bottom nor near the shore can be said to be in the pelagic zone. The word pelagic is derived from Greek πέλαγος, meaning open sea, the pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom. Conditions differ deeper in the water such that as pressure increases with depth. Depending on the depth, the column, rather like the Earths atmosphere. The pelagic zone occupies 1,330 million km3 with a depth of 3.68 km. Pelagic life decreases with increasing depth and it is affected by light intensity, pressure, temperature, salinity, the supply of dissolved oxygen and nutrients, and the submarine topography, which is called bathymetry. In deep water, the zone is sometimes called the open-ocean zone. In other contexts, coastal water not near the bottom is still said to be in the pelagic zone, the pelagic zone can be contrasted with the benthic and demersal zones at the bottom of the sea. The benthic zone is the region at the very bottom of the sea. It includes the sediment surface and some subsurface layers, Marine organisms living in this zone, such as clams and crabs, are called benthos. The demersal zone is just above the benthic zone and it can be significantly affected by the seabed and the life that lives there. Demersal fish are known as bottom feeders and groundfish. Depending on how deep the sea is, the zone can extend over up to five horizontal layers in the ocean. From the top down, these are, From the surface down to around 200 m This is the zone at the surface of the sea where enough light is available for photosynthesis. Nearly all primary production in the ocean occurs here, consequently, plants and animals are largely concentrated in this zone. Examples of organisms living in this zone are plankton, floating seaweed, jellyfish, tuna, many sharks, from 200 m down to around 1,000 m The name for this zone stems from Greek μέσον, meaning middle. Although some light penetrates this second layer it is insufficient for photosynthesis, at about 500 m the water also becomes depleted of oxygen. Organisms survive this environment by having more efficient gills or by minimizing movement, examples of animals that live here are swordfish, squid, Anarhichadidae or wolffish and some species of cuttlefish
14.
Oceanic zone
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The oceanic zone begins in the area off shore where the water measures 200 meters deep or deeper and extends to the ocean floor. It is the region of open sea beyond the edge of the continental shelf, the oceanic zone has a wide array of undersea terrain, including crevices that are often deeper than Mount Everest is tall, as well as deep-sea volcanoes and ocean basins. While it is difficult for life to sustain itself in this type of environment. The oceanic zone is subdivided into the epipelagic, mesopelagic, the epipelagic zone, also called the sunlit zone, receives enough sunlight to support photosynthesis. The temperatures in this zone range anywhere from 40 to −3 °C, the mesopelagic zone, where only small amounts of light penetrate, lies below the epipelagic zone. This zone is referred to as the Twilight Zone due to its scarce amount of light. Temperatures in the zone range from 5 to 4 °C. The pressure is higher here, it can be up to 1,470 pounds per square inch, 90% of the ocean lies in the bathypelagic zone into which no light penetrates. This is also called the zone and the deep ocean. Due to the lack of sunlight, photosynthesis cannot occur. Water pressure is intense and the temperatures are near freezing Oceanographers have divided the ocean into zones based on how far light reaches. All of the zones can be found in the oceanic zone. The epipelagic zone is the one closest to the surface and is the best lit and it extends to 200 meters and contains both phytoplankton and zooplankton that can support larger organisms like marine mammals and some types of fish. Past 200 meters, not enough light penetrates the water to support life, there are creatures however, which thrive around hydrothermal vents, or geysers located on the ocean floor that expel super heated water that is rich in minerals. These organisms feed off of chemosynthetic bacteria, which use the super heated water, the existence of these bacteria allow creatures like squids, hatchet fish, octopuses, tube worms, giant clams, spider crabs and other organisms to survive. Due to the darkness in the zones past the epipelagic zone, many organisms that survive in the deep oceans do not have eyes. Often the light is green in colour, because many marine organisms are sensitive to blue light. Two chemicals, luciferin and luciferase that react with one another to create a soft glow, the process by which bioluminescence is created is very similar to what happens when a glow stick is broken
15.
Hydrothermal vent
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A hydrothermal vent is a fissure in a planets surface from which geothermally heated water issues. Hydrothermal vents are found near volcanically active places, areas where tectonic plates are moving apart, ocean basins. Hydrothermal vents exist because the earth is both active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers, under the sea, hydrothermal vents may form features called black smokers. Chemosynthetic bacteria and archaea form the base of the chain, supporting diverse organisms, including giant tube worms, clams, limpets. Active hydrothermal vents are believed to exist on Jupiters moon Europa, and Saturns moon Enceladus, Hydrothermal vents in the deep ocean typically form along the mid-ocean ridges, such as the East Pacific Rise and the Mid-Atlantic Ridge. These are locations where two plates are diverging and new crust is being formed. The proportion of each varies from location to location, in contrast to the approximately 2 °C ambient water temperature at these depths, water emerges from these vents at temperatures ranging from 60 to as high as 464 °C. Due to the hydrostatic pressure at these depths, water may exist in either its liquid form or as a supercritical fluid at such temperatures. The critical point of water is 375 °C at a pressure of 218 atmospheres, however, introducing salinity into the fluid raises the critical point to higher temperatures and pressures. The critical point of seawater is 407 °C and 298.5 bars, accordingly, if a hydrothermal fluid with a salinity of 3.2 wt. % NaCl vents above 407 °C and 298.5 bars, furthermore, the salinity of vent fluids have been shown to vary widely due to phase separation in the crust. The critical point for lower salinity fluids is at lower temperature and pressure conditions than that for seawater, for example, a vent fluid with a 2.24 wt. % NaCl salinity has the point at 400 °C and 280.5 bars. Thus, water emerging from the hottest parts of some hydrothermal vents can be a supercritical fluid, examples of supercritical venting are found at several sites. Sister Peak vents low salinity phase-separated, vapor-type fluids, sustained venting was not found to be supercritical but a brief injection of 464 °C was well above supercritical conditions. A nearby site, Turtle Pits, was found to vent low salinity fluid at 407 °C, which is above the critical point of the fluid at that salinity. A vent site in the Cayman Trough named Beebe, which is the worlds deepest known hydrothermal site at ~5000 m below sea level, has shown sustained supercritical venting at 401 °C and 2.3 wt% NaCl
16.
Cold seep
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A cold seep is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. Cold does not mean that the temperature of the seepage is lower than that of the sea water. On the contrary, its temperature is slightly higher. Cold seeps constitute a biome supporting several endemic species, cold seeps develop unique topography over time, where reactions between methane and seawater create carbonate rock formations and reefs. These reactions may also be dependent on bacterial activity, ikaite, a hydrous calcium carbonate, can be associated with oxidizing methane at cold seeps. Types of cold seeps can be distinguished according to the depth, as cold seeps. Oil and methane seep out of fissures, get diffused by sediment. Methane is the component of what we commonly refer to as natural gas. But in addition to being an important energy source for humans, cold seep biota below 200 m typically exhibit much greater systematic specialization and reliance on chemoautotrophy than those from shelf depths. Deep-sea seeps sediments are highly heterogeneous and they sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist and background fauna. Biological research in cold seeps and hydrothermal vents has been focused on the microbiology. Much less research has been done on the smaller benthic fraction at the size of the meiofauna, community compositions orderly shift from one set of species to another is called ecological succession, The first type of organism to take advantage of this deep-sea energy source is bacteria. Aggregating into bacterial mats at cold seeps, these bacteria metabolize methane and this process of obtaining energy from chemicals is known as chemosynthesis. During this initial stage, when methane is relatively abundant, dense mussel beds also form near the cold seep, mostly composed of species in the genus Bathymodiolus, these mussels do not directly consume food. Instead, they are nourished by symbiotic bacteria that produce energy from methane. Chemosynthetic bivalves are prominent constituents of the fauna of cold seeps and are represented in that setting by five families and this microbial activity produces calcium carbonate, which is deposited on the seafloor and forms a layer of rock. During a period lasting up to decades, these rock formations attract siboglinid tubeworms. Like the mussels, tubeworms rely on chemosynthetic bacteria for survival, true to any symbiotic relationship, a tubeworm also provides for their bacteria by appropriating hydrogen sulfide from the environment
17.
Demersal zone
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The demersal zone is the part of the sea or ocean consisting of the part of the water column near to the seabed and the benthos. The demersal zone is just above the zone and forms a layer of the larger profundal zone. The distinction between species of fish and pelagic species is not always clear cut. Two types of fish inhabit the zone, those that are heavier than water and rest on the seabed. In many species of fish, neutral buoyancy is maintained by a swim bladder which can be expanded or contracted as the circumstances require. A disadvantage of this method is that adjustments need to be made constantly as the pressure varies when the fish swims higher and lower in the water column. An alternative buoyancy aid is the use of lipids, these are less dense water and squalene. In the velvet belly lanternshark, a species, 17% of the bodyweight is liver. Benthic rays and skates have smaller livers with lower concentrations of lipids, they are denser than water. Some fish have no buoyancy aids but use their pectoral fins which are so angled as to lift as they swim. The disadvantage of this is that, if they stop swimming, the fish sink, demersal fish have various feeding strategies, many feed on zooplankton or organisms or algae on the seabed, some of these feed on epifauna, while others specialise on infauna. Others are scavengers, eating the remains of plants or animals while still others are predators. Zooplankton are animals that drift with the current, but many have limited means of locomotion and have some control over the depths at which they drift. They use gas-filled sacs or accumulations of substances with low densities to provide buoyancy, where the adult, benthic organism is limited to life in a certain range of depths, their larvae need to optimise their chances of settling on a suitable substrate. Cuttlefish are able to adjust their buoyancy using their cuttlebones, lightweight rigid structures with cavities filled with gas and this enables them to swim at varying depths. Another invertebrate that feeds on the seabed and has swimming abilities is the nautilus, which stores gas in its chambers and adjusts its buoyancy by use of osmosis, pumping water in and out
18.
Benthic zone
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The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos, e. g. the benthic community, including crustaceans. The organisms generally live in relationship with the substrate bottom. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, the benthic region of the ocean begins at the shore line and extends downward along the surface of the continental shelf out to sea. The continental shelf is a gently sloping benthic region that extends away from the land mass, at the continental shelf edge, usually about 200 meters deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the sea floor. The deep-sea floor is called the plain and is usually about 4,000 meters deep. The ocean floor is not all flat but has submarine ridges, for comparison, the pelagic zone is the descriptive term for the ecological region above the benthos, including the water-column up to the surface. For information on animals that live in the areas of the oceans see aphotic zone. Generally, these life forms that tolerate cool temperatures and low oxygen levels. Benthos are the organisms live in the benthic zone, and are different from those elsewhere in the water column. Many are adapted to live on the substrate, in their habitats they can be considered as dominant creatures, but they are often a source of prey for Carcharhinidae such as the lemon shark. Many organisms adapted to deep-water pressure cannot survive in the parts of the water column. The pressure difference can be very significant, because light does not penetrate very deep into ocean-water, the energy source for the benthic ecosystem is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain, most organisms in the zone are scavengers or detritivores. Some microorganisms use chemosynthesis to produce biomass, Benthic organisms can be divided into two categories based on whether they make their home on the ocean floor or an inch or two into the ocean floor. Those living on the surface of the floor are known as epifauna. Those who live burrowed into the floor are known as infauna
19.
Mountain
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A mountain is a large landform that stretches above the surrounding land in a limited area, usually in the form of a peak. A mountain is steeper than a hill. Mountains are formed through tectonic forces or volcanism and these forces can locally raise the surface of the earth. Mountains erode slowly through the action of rivers, weather conditions, a few mountains are isolated summits, but most occur in huge mountain ranges. High elevations on mountains produce colder climates than at sea level and these colder climates strongly affect the ecosystems of mountains, different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction and recreation, the highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8,850 m above mean sea level. The highest known mountain on any planet in the Solar System is Olympus Mons on Mars at 21,171 m, there is no universally accepted definition of a mountain. Elevation, volume, relief, steepness, spacing and continuity have been used as criteria for defining a mountain, whether a landform is called a mountain may depend on local usage. The highest point in San Francisco, California, is called Mount Davidson, notwithstanding its height of 300 m, similarly, Mount Scott outside Lawton, Oklahoma is only 251 m from its base to its highest point. Whittows Dictionary of Physical Geography states Some authorities regard eminences above 600 metres as mountains, in addition, some definitions also include a topographical prominence requirement, typically 100 or 500 feet. For a while, the US defined a mountain as being 1,000 feet or taller, any similar landform lower than this height was considered a hill. However, today, the United States Geological Survey concludes that these terms do not have technical definitions in the US, using these definitions, mountains cover 33% of Eurasia, 19% of South America, 24% of North America, and 14% of Africa. As a whole, 24% of the Earths land mass is mountainous, there are three main types of mountains, volcanic, fold, and block. All three types are formed from plate tectonics, when portions of the Earths crust move, crumple, compressional forces, isostatic uplift and intrusion of igneous matter forces surface rock upward, creating a landform higher than the surrounding features. The height of the feature makes it either a hill or, if higher and steeper, major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity. Volcanoes are formed when a plate is pushed below another plate, at a depth of around 100 km, melting occurs in rock above the slab, and forms magma that reaches the surface. When the magma reaches the surface, it builds a volcanic mountain. Examples of volcanoes include Mount Fuji in Japan and Mount Pinatubo in the Philippines, the magma does not have to reach the surface in order to create a mountain, magma that solidifies below ground can still form dome mountains, such as Navajo Mountain in the US
20.
Ocean
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An ocean is a body of saline water that composes much of a planets hydrosphere. On Earth, an ocean is one of the major divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern, the word sea is often used interchangeably with ocean in American English but, strictly speaking, a sea is a body of saline water partly or fully enclosed by land. The ocean contains 97% of Earths water, and oceanographers have stated that less than 5% of the World Ocean has been explored, the total volume is approximately 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the component of Earths hydrosphere, it is integral to all known life, forms part of the carbon cycle. The world ocean is the habitat of 230,000 known species, but because much of it is unexplored, the origin of Earths oceans remains unknown, oceans are thought to have formed in the Hadean period and may have been the impetus for the emergence of life. Extraterrestrial oceans may be composed of water or other elements and compounds, the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many planets and natural satellites, notably. The Solar Systems giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of water within a circumstellar habitable zone. Ocean planets are a type of planet with a surface completely covered with liquid. The concept of Ōkeanós has an Indo-European connection, Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases, though generally described as several separate oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean. This concept of a body of water with relatively free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits. The Mid-Oceanic Ridge of the World are connected and form the Ocean Ridge, the continuous mountain range is 65,000 km long, and the total length of the oceanic ridge system is 80,000 km long
21.
Seabed
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The seabed is the bottom of the ocean. Most of the oceans have a structure, created by common physical phenomena, mainly from tectonic movement. The mid-ocean ridge, as its name implies, is a rise through the middle of all the oceans. Typically a rift runs along the edge of this ridge, along tectonic plate edges there are typically oceanic trenches – deep valleys, created by the mantle circulation movement from the mid-ocean mountain ridge to the oceanic trench. Hotspot volcanic island ridges are created by volcanic activity, erupting periodically, in areas with volcanic activity and in the oceanic trenches there are hydrothermal vents – releasing high pressure and extremely hot water and chemicals into the typically freezing water around it. Deep ocean water is divided into layers or zones, each with features of salinity, pressure, temperature and marine life. Lying along the top of the plain is the abyssal zone. The hadal zone – which includes the oceanic trenches, lies between 6, 000–11,000 metres and is the deepest oceanic zone, the acronym mbsf meaning meters below the seafloor is a convention used for depths below the seafloor. Benthos is the community of organisms which live on, in, or near the seabed and this community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths. The benthic zone is the region on, in and immediately above the seabed, including the sediment surface. Benthos generally live in relationship with the substrate bottom. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, each area of the seabed has typical features such as common soil composition, typical topography, salinity of water layers above it, marine life, magnetic direction of rocks, and sedimentation. Seabed topography is flat where sedimentation is heavy and covers the tectonic features, marine life is abundant in the deep sea, especially around hydrothermal vents. Large deep sea communities of life have been discovered around black and white smokers—vents emitting chemicals toxic to humans. This marine life receives its energy both from the temperature difference and from chemosynthesis by bacteria. Brine pools are another seabed feature, usually connected to cold seeps, the seabed has been explored by submersibles such as Alvin and, to some extent, scuba divers with special equipment. The process that adds new material to the ocean floor is seafloor spreading. In recent years satellite images show a very clear mapping of the seabed, some childrens play songs include elements such as Theres a hole at the bottom of the sea, or A sailor went to sea
22.
Sea level
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Mean sea level is an average level of the surface of one or more of Earths oceans from which heights such as elevations may be measured. A common and relatively straightforward mean sea-level standard is the midpoint between a low and mean high tide at a particular location. Sea levels can be affected by factors and are known to have varied greatly over geological time scales. The careful measurement of variations in MSL can offer insights into ongoing climate change, the term above sea level generally refers to above mean sea level. Precise determination of a sea level is a difficult problem because of the many factors that affect sea level. Sea level varies quite a lot on several scales of time and this is because the sea is in constant motion, affected by the tides, wind, atmospheric pressure, local gravitational differences, temperature, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point, for example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. One measures the values of MSL in respect to the land, hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates. In the UK, the Ordnance Datum is the sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the datum was MSL at the Victoria Dock, in Hong Kong, mPD is a surveying term meaning metres above Principal Datum and refers to height of 1. 230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and it is used for a part of continental Europe and main part of Africa as official sea level. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001, height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum. It is also used in aviation, where some heights are recorded and reported with respect to sea level, and in the atmospheric sciences. An alternative is to base height measurements on an ellipsoid of the entire Earth, in aviation, the ellipsoid known as World Geodetic System 84 is increasingly used to define heights, however, differences up to 100 metres exist between this ellipsoid height and mean tidal height. The alternative is to use a vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, the elevation of a mountain denotes the highest point or summit and is typically illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, for one such case, see Amsterdam Airport Schiphol
23.
Island
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An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, an island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, an island may be described as such, despite the presence of an artificial land bridge. Example, Singapore and its causeway, or the various Dutch delta islands, there are two main types of islands in the sea, continental and oceanic. The word island derives from Middle English iland, from Old English igland, Old English ieg is actually a cognate of Swedish ö and German Aue, and related to Latin aqua. There is a difference between islands and continents in terms of geology, continents sit on continental lithosphere which is part of tectonic plates floating high on Earths mantle. Oceanic crust is also part of tectonic plates, but it is denser than continental lithosphere, Islands are either extensions of the oceanic crust or geologically they are part of some continent sitting on continental lithosphere. This holds true for Australia, which sits on its own continental lithosphere, continental islands are bodies of land that lie on the continental shelf of a continent. A special type of island is the microcontinental island, which is created when a continent is rifted. Examples are Madagascar and Socotra off Africa, the Kerguelen Islands, New Caledonia, New Zealand, another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. While some are transitory and may disappear if the volume or speed of the current changes, others are stable, oceanic islands are islands that do not sit on continental shelves. The vast majority are volcanic in origin, such as Saint Helena in the South Atlantic Ocean, the few oceanic islands that are not volcanic are tectonic in origin and arise where plate movements have lifted up the ocean floor above the surface. Examples are Saint Peter and Paul Rocks in the Atlantic Ocean, one type of volcanic oceanic island is found in a volcanic island arc. These islands arise from volcanoes where the subduction of one plate under another is occurring, examples are the Aleutian Islands, the Mariana Islands, and most of Tonga in the Pacific Ocean. The only examples in the Atlantic Ocean are some of the Lesser Antilles, another type of volcanic oceanic island occurs where an oceanic rift reaches the surface. There are two examples, Iceland, which is the second largest volcanic island, and Jan Mayen. A third type of oceanic island is formed over volcanic hotspots. A hotspot is more or less stationary relative to the tectonic plate above it
24.
Islet
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An islet is a very small island. As suggested by its origin as islette, an Old French diminutive of isle, use of the term implies small size, but little attention is given to drawing an upper limit on its applicability. Cay or Key – an islet formed by the accumulation of sand deposits atop a reef Motu – A reef islet formed by broken coral and sand. River island – A small islet within the current of a river, rock – A rock, in the sense of a type of islet, is an uninhabited landform composed of rock, lying offshore, and having at most minimal vegetation. Sandbar – An exposed sandbar is another type of islet, Sea stack – A thin, vertical landform jutting out of a body of water. Skerry – A small rocky island, usually defined to be too small for habitation, subsidiary islets – A more technical application is to small land features, isolated by water, lying off the shore of a larger island. Likewise, any emergent land in an atoll is called an islet. Tidal island – Often small islands lie off the mainland of an area, being connected to it in low tide. In the Caribbean and West Atlantic, islets are often called cays or keys, rum Cay in the Bahamas and the Florida Keys off Florida are examples of islets. In the Channel Islands, they are identified by the suffix -hou from the Norse -holm. In Scotland and Ireland, they are often called inches, from the Gaelic innis, which originally meant island, in Ireland they are often termed skerries. In and around Polynesia, islets are widely known by the term motu, in and around the River Thames in England, small islands are known as aits or eyots. One long-term dispute over the status of such an islet was that of Snake Island, there are thousands of islets on Earth, approximately 24,000 islands and islets in the Stockholm archipelago alone. The following is a list of example islets from around the world, Islands or Rocks, Is that the Real Question. The Treatment of Islands in the Delimitation of Maritime Boundaries, in Myron H. Nordquist, John Norton Moore, Alfred H. A. The Law of the Sea Convention, US Accession and Globalization
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Cliff
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In geography and geology, a cliff is a vertical, or nearly vertical, rock exposure. Cliffs are formed as erosion landforms by the processes of weathering, Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually formed by rock that is resistant to weathering, sedimentary rocks most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs, an escarpment is a type of cliff, formed by the movement of a geologic fault or a landslide. Most cliffs have some form of slope at their base. In arid areas or under high cliffs, they are generally exposed jumbles of fallen rock, in areas of higher moisture, a soil slope may obscure the talus. Many cliffs also feature tributary waterfalls or rock shelters, sometimes a cliff peters out at the end of a ridge, with tea tables or other types of rock columns remaining. Coastal erosion may lead to the formation of sea cliffs along a receding coastline, the Ordnance Survey distinguishes between cliffs and outcrops. Cliff is a Romance loanword that has its origins in the Latin forms clivus / clevus. Given that a cliff need not be vertical, there can be ambiguity about whether a given slope is a cliff or not. For example, given a vertical rock wall above a very steep slope. Listings of cliffs are thus inherently uncertain, some of the largest cliffs on Earth are found underwater. For example, an 8,000 m drop over a 4,250 m span can be found at a ridge sitting inside the Kermadec Trench. One candidate for highest cliff in the world is Nanga Parbats Rupal Face, according to other sources, the highest cliff in the world, about 1,340 m high, is the east face of Great Trango in the Karakoram mountains of northern Pakistan. The location of the worlds highest sea cliffs depends also on the definition of cliff that is used, guinness World Records states it is Kalaupapa, Hawaii, at 1,010 m high. Another contender is the face of Mitre Peak, which drops 1,683 m to Milford Sound. These are subject to a less stringent definition, as the slope of these cliffs at Kaulapapa is about 1.7, corresponding to an angle of 60 degrees. A more vertical drop into the sea can be found at Maujit Qaqarssuasia which is situated in the Torssukátak fjord area at the tip of South Greenland
26.
Volcano
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A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology. The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, therefore, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire. Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateaus
27.
Oceanography
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Oceanography, also known as oceanology, is the study of the physical and the biological aspects of the ocean. Paleoceanography studies the history of the oceans in the geologic past, humans first acquired knowledge of the waves and currents of the seas and oceans in pre-historic times. Observations on tides were recorded by Aristotle and Strabo, early exploration of the oceans was primarily for cartography and mainly limited to its surfaces and of the animals that fishermen brought up in nets, though depth soundings by lead line were taken. Although Juan Ponce de León in 1513 first identified the Gulf Stream, Franklin measured water temperatures during several Atlantic crossings and correctly explained the Gulf Streams cause. Franklin and Timothy Folger printed the first map of the Gulf Stream in 1769-1770, information on the currents of the Pacific Ocean was gathered by explorers of the late 18th century, including James Cook and Louis Antoine de Bougainville. James Rennell wrote the first scientific textbooks on oceanography, detailing the current flows of the Atlantic, during a voyage around the Cape of Good Hope in 1777, he mapped the banks and currents at the Lagullas. He was also the first to understand the nature of the intermittent current near the Isles of Scilly, Robert FitzRoy published a four-volume report of the Beagles three voyages. In 1841–1842 Edward Forbes undertook dredging in the Aegean Sea that founded marine ecology, the first superintendent of the United States Naval Observatory, Matthew Fontaine Maury devoted his time to the study of marine meteorology, navigation, and charting prevailing winds and currents. His 1855 textbook Physical Geography of the Sea was one of the first comprehensive oceanography studies, many nations sent oceanographic observations to Maury at the Naval Observatory, where he and his colleagues evaluated the information and distributed the results worldwide. Despite all this, human knowledge of the oceans remained confined to the topmost few fathoms of the water, almost nothing was known of the ocean depths. The Royal Navys efforts to all of the worlds coastlines in the mid-19th century reinforced the vague idea that most of the ocean was very deep. As exploration ignited both popular and scientific interest in the regions and Africa, so too did the mysteries of the unexplored oceans. The seminal event in the founding of the science of oceanography was the 1872-76 Challenger expedition. As the first true oceanographic cruise, this laid the groundwork for an entire academic. In response to a recommendation from the Royal Society, The British Government announced in 1871 an expedition to explore worlds oceans, charles Wyville Thompson and Sir John Murray launched the Challenger expedition. The Challenger, leased from the Royal Navy, was modified for scientific work, under the scientific supervision of Thomson, Challenger travelled nearly 70,000 nautical miles surveying and exploring. On her journey circumnavigating the globe,492 deep sea soundings,133 bottom dredges,151 open water trawls and 263 serial water temperature observations were taken, around 4,700 new species of marine life were discovered. The result was the Report Of The Scientific Results of the Exploring Voyage of H. M. S, Murray, who supervised the publication, described the report as the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries
28.
Deep sea
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The deep sea or deep layer is the lowest layer in the ocean, existing below the thermocline and above the seabed, at a depth of 1000 fathoms or more. Little or no light penetrates this part of the ocean, for this reason, scientists once assumed that life would be sparse in the deep ocean, but virtually every probe has revealed that, on the contrary, life is abundant in the deep ocean. From the time of Pliny until the nineteenth century. humans believed there was no life in the deep. It took an expedition in the ship Challenger between 1872 and 1876 to prove Pliny wrong, its deep-sea dredges and trawls brought up living things from all depths that could be reached. Yet even in the century scientists continued to imagine that life at great depth was insubstantial. The eternal dark, the almost inconceivable pressure, and the cold that exist below one thousand meters were, they thought, so forbidding as to have all. The reverse is in fact true, lies the largest habitat on earth. In 1960, the Bathyscaphe Trieste descended to the bottom of the Mariana Trench near Guam, at 10,911 m, if Mount Everest were submerged there, its peak would be more than a mile beneath the surface. The Trieste was retired, and for a while the Japanese remote-operated vehicle Kaikō was the vessel capable of reaching this depth. It was lost at sea in 2003, in May and June 2009, the hybrid-ROV Nereus returned to the Challenger Deep for a series of three dives to depths exceeding 10900 meters. It has been suggested that more is known about the Moon than the deepest parts of the ocean, little was known about the extent of life on the deep ocean floor until the discovery of thriving colonies of shrimps and other organisms around hydrothermal vents in the late 1970s. Before the discovery of the vents, it had been accepted that almost all life on earth obtained its energy from the sun. The new discoveries revealed groups of creatures that obtained nutrients and energy directly from thermal sources, the revolutionary discovery that life can exist under these extreme conditions changed opinions about the chances of there being life elsewhere in the universe. Scientists now speculate that Europa, one of Jupiters moons, may be able to support life beneath its icy surface, natural light does not penetrate the deep ocean, with the exception of the upper parts of the mesopelagic. Since photosynthesis is not possible, plants cannot live in this zone, since plants are the primary producers of almost all of earths ecosystems, life in this area of the ocean must depend on energy sources from elsewhere. Except for the close to the hydrothermal vents, this energy comes from organic material drifting down from the photic zone. The sinking organic material is composed of algal particulates, detritus, and other forms of biological waste, because pressure in the ocean increases by about 1 atmosphere for every 10 meters of depth, the amount of pressure experienced by many marine organisms is extreme. With the advent of traps that incorporate a special pressure-maintaining chamber, salinity is remarkably constant throughout the deep sea, at about 35 parts per thousand
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Guyot
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A guyot, also known as a tablemount, is an isolated underwater volcanic mountain, with a flat top over 200 m below the surface of the sea. The diameters of these flat summits can exceed 10 km, the guyot was named after the Swiss-American geographer and geologist Arnold Henry Guyot. The term was coined by Harry Hammond Hess, guyots are most commonly found in the Pacific Ocean. Guyots show evidence of having been above the surface with gradual subsidence through stages from fringed reefed mountain, coral atoll, the steepness gradient of most guyots is about 20 degrees. To technically be considered a guyot or tablemount, they must stand at least 914 m tall, however, there are many undersea mounts that can range from just less than 91 m to around 914 m. Very large oceanic volcanic constructions, hundreds of km across, are called oceanic plateaus, Seamounts are made by extrusion of lavas piped upward in stages from sources within the Earths mantle to vents on the seafloor. Seamounts provide data on movements of tectonic plates on which they ride, the trend of a seamount chain traces the direction of motion of the lithospheric plate over a more or less fixed heat source in the underlying asthenosphere part of the Earths mantle. There are thought to be up to an estimated 50,000 seamounts in the Pacific basin, the Emperor Seamounts are an excellent example of an entire volcanic chain undergoing this process and contain many guyots among their other examples. Another factor contributing to the guyots being underwater has to do with the oceanic ridges, mid-ocean ridges gradually spread apart over time, due to molten lava being pushed up under the surface of the earth and creating new rock. As the mid-ocean ridges spread apart, the move with them. Thus, the amount of time that passes, the deeper the guyots become. One guyot in particular, the Great Meteor Tablemount in the Northeast Atlantic Ocean, the guyots diameter is 110 km. Guyots are also associated with specific lifeforms and varying amounts of organic matter, local increases in chlorophyll a, enhanced carbon incorporation rates and changes in phytoplankton species composition were associated with the seamount. Guyots were first recognized by Harry Hammond Hess in 1945 who collected data using echo-sounding equipment on a ship he commanded during World War II, the data showed the configuration of the seafloor where he saw that some undersea mountains had flat tops. Hess postulated they were once volcanic islands that were beheaded by wave action yet they are now deep under sea level and this idea was used to help bolster the theory of plate tectonics. Hawaiian–Emperor seamount chain New England Seamounts Kodiak–Bowie Seamount chain Evolution of Hawaiian volcanoes Hotspot Atoll Seamount Wilde guyot map from Texas A&M ]
30.
Hawaiian Islands
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Formerly the group was known to Europeans and Americans as the Sandwich Islands, a name chosen by James Cook in honor of the then First Lord of the Admiralty John Montagu, 4th Earl of Sandwich. The contemporary name is derived from the name of the largest island, the Hawaiian monarchy was overthrown in 1893 and the United States annexed the islands in 1898. The Hawaiian Islands are the peaks of a great undersea mountain range known as the Hawaiian–Emperor seamount chain. The islands are about 1,860 miles from the nearest continent and this name was in use until the 1840s, when the local name Hawaii gradually began to take precedence. The Hawaiian Islands have a land area of 6,423.4 square miles. Except for Midway, which is a territory of the United States. The eight main islands of Hawaii are listed here and this number includes all minor islands and islets, or very small island, offshore of the main islands and individual islets in each atoll. Thus, the southeast island is volcanically active, whereas the islands on the northwest end of the archipelago are older and typically smaller, the age of the archipelago has been estimated using potassium-argon dating methods.4 Ma. The only active volcanism in the last 200 years has been on the island, Hawaiʻi. The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images, almost all of the magma of the hotspot has the composition of basalt, and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained gabbro and diabase, nephelinite is exposed on the islands but is extremely rare. Hawaiʻi island is the biggest and youngest island in the chain, mauna Loa, taking up over half of the Big Island, is the largest shield volcano on the Earth. The measurement from sea level to summit is more than 2.5 miles, the Hawaiian Islands have many earthquakes, generally caused by volcanic activity. Most of the earthquake monitoring took place in Hilo, by missionaries Titus Coan, Sarah J. Lyman. From 1833 to 1896, approximately 4 or 5 earthquakes were reported per year, Hawaii accounted for 7. 3% of the United States reported earthquakes with a magnitude 3.5 or greater from 1974 to 2003, with a total 1533 earthquakes. Hawaii ranked as the state with the third most earthquakes over this period, after Alaska. On October 15,2006, there was an earthquake with a magnitude of 6.7 off the northwest coast of the island of Hawaii, the initial earthquake was followed approximately five minutes later by a magnitude 5.7 aftershock. Minor-to-moderate damage was reported on most of the Big Island, several major roadways became impassable from rock slides, and effects were felt as far away as Honolulu, Oahu, nearly 150 miles from the epicenter
31.
Marine ecosystem
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Marine ecosystems are among the largest of Earths aquatic ecosystems. Examples include salt marshes, intertidal zones, estuaries, lagoons, mangroves, coral reefs, the sea. They can be contrasted with freshwater ecosystems, which have a salt content. Marine waters cover two-thirds of the surface of the Earth, such places are considered ecosystems because the plant life supports the animal life and vice versa. Marine ecosystems are essential for the health of both marine and terrestrial environments. According to the World Resource Center, coastal habitats account for about one-third of marine biological productivity, estuarine ecosystems, such as salt marshes, seagrass meadows and mangrove forests, are among the most productive ecosystems on the planet. Coral reefs provide food and shelter to the highest levels of diversity in the world. Marine ecosystems usually have a large biodiversity and are thought to have a good resistance against invasive species. However, exceptions have been observed, and the mechanisms responsible in determining the success of an invasion are not yet clear, barange M, Field JG, Harris RP, Eileen E, Hofmann EE, Perry RI and Werner F Marine Ecosystems and Global Change Oxford University Press. ISBN 978-0-19-955802-5 Boyd IL, Wanless S and Camphuysen CJ Top predators in marine ecosystems, their role in monitoring, ISBN 978-0-521-84773-5 Davenport J Challenges to Marine Ecosystems, Proceedings of the 41st European Marine Biology Symposium Volume 202 of Developments in hydrobiology. ISBN 978-1-4020-8807-0 Levner E, Linkov I and Proth J Strategic management of marine ecosystems Springer, Volume 50 of NATO Science Series IV. ISBN 978-1-4020-3158-8 Mann KH and Lazier JRN Dynamics of marine ecosystems, ISBN 978-1-4051-1118-8 Moustakas A and Karakassis I How diverse is aquatic biodiversity research. U. S. Environmental Protection Agency—EPA, Marine Ecosystems Encyclopædia Britannica Online, Marine ecosystem —, smithsonian Institution, Ocean Portal Marine Ecosystems Research Programme
32.
Plankton
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Plankton are the diverse collection of organisms that live in the water column of large bodies of water and are unable to swim against a current. They provide a source of food to many large aquatic organisms, such as fish. These organisms include bacteria, archaea, algae, protozoa and drifting or floating animals that inhabit, for example, essentially, plankton are defined by their ecological niche rather than any phylogenetic or taxonomic classification. Though many planktonic species are microscopic in size, plankton includes organisms covering a range of sizes. The name plankton is derived from the Greek adjective πλαγκτός, meaning errant and it was coined by Victor Hensen. Plankton typically flow with ocean currents, while some forms are capable of independent movement and can swim hundreds of meters vertically in a single day, their horizontal position is primarily determined by the surrounding currents. This is in contrast to nekton organisms that can swim against the ambient flow, within the plankton, holoplankton spend their entire life cycle as plankton. By contrast, meroplankton are only planktic for part of their lives, examples of meroplankton include the larvae of sea urchins, starfish, crustaceans, marine worms, and most fish. Plankton abundance and distribution are strongly dependent on such as ambient nutrient concentrations, the physical state of the water column. The study of plankton is termed planktology and an individual is referred to as a plankter. The adjective planktonic is widely used in both the scientific and popular literature, and is an accepted term. However, from the standpoint of prescriptive grammar the less commonly used planktic is more strictly the correct adjective, when deriving English words from their Greek or Latin roots the gender specific ending is normally dropped, using only the root of the word in the derivation. Among the more important groups are the diatoms, cyanobacteria, dinoflagellates and coccolithophores, zooplankton, small protozoans or metazoans that feed on other plankton and telonemia. Some of the eggs and larvae of larger animals, such as fish, crustaceans, bacterioplankton, bacteria and archaea, which play an important role in remineralising organic material down the water column. Mycoplankton, fungi and fungus-like organisms, which also are significant in nutrient cycling and this scheme divides the plankton community into broad producer, consumer and recycler groups. However, determining the level of some plankton is not straightforward. For example, although most dinoflagellates are either photosynthetic producers or heterotrophic consumers, Plankton are also often described in terms of size. Usually the following divisions are used, However, some of terms may be used with very different boundaries
33.
Coral
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Corals are marine invertebrates in the class Anthozoa of phylum Cnidaria. They typically live in colonies of many identical individual polyps. The group includes the important reef builders that inhabit tropical oceans, a coral group is a colony of myriad genetically identical polyps. Each polyp is an animal typically only a few millimeters in diameter. A set of tentacles surround a central mouth opening, an exoskeleton is excreted near the base. Over many generations, the colony creates a large skeleton that is characteristic of the species. Individual heads grow by reproduction of polyps. Corals also breed sexually by spawning, polyps of the same species release gametes simultaneously over a period of one to several nights around a full moon and these are commonly known as zooxanthellae and the corals that contain them are zooxanthellate corals. Such corals require sunlight and grow in clear, shallow water, other corals do not rely on zooxanthellae and can live in much deeper water, with the cold-water genus Lophelia surviving as deep as 3,000 metres. Some have been found on the Darwin Mounds, north-west of Cape Wrath, Corals have also been found as far north as off the coast of Washington State and the Aleutian Islands. In his Scala Naturae, Aristotle classified corals as zoophyta, animals that had characteristics of plants and were therefore hypothetically in between animals and plants, the Persian polymath Al-Biruni classified sponges and corals as animals, arguing that they respond to touch. The phylogeny of Anthozoans is not clearly understood and a number of different models have been proposed, within the Hexacorallia, the sea anemones, coral anemones and stony corals may constitute a monophyletic grouping united by their eight-fold symmetry and cnidocyte trait. The Octocorallia appears to be monophyletic, and primitive members of this group may have been stolonate, the cladogram presented here comes from a 2014 study by Stampar et al. which was based on the divergence of mitochondrial DNA within the group and on nuclear markers. Corals are classified in the class Anthozoa of the phylum Cnidaria and they are divided into three subclasses, Hexacorallia, Octocorallia, and Ceriantharia. The Hexacorallia include the stony corals, the sea anemones and the zoanthids and these groups have polyps that generally have 6-fold symmetry. The Octocorallia include blue coral, soft corals, sea pens and these groups have polyps with 8-fold symmetry, each polyp having eight tentacles and eight mesenteries. Fire corals are not true corals, being in the order Anthomedusa of the class Hydrozoa, Corals are sessile animals in the class Anthozoa and differ from most other cnidarians in not having a medusa stage in their life cycle. The body unit of the animal is a polyp, most corals are colonial, the initial polyp budding to produce another and the colony gradually developing from this small start
34.
Fish
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A fish is any member of a group of animals that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. They form a group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous, tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered obsolete or paraphyletic by excluding the tetrapods, because in this manner the term fish is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology. The traditional term pisces is considered a typological, but not a phylogenetic classification, the earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts, fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators, the first fish with jaws appeared in the Silurian period, after which many became formidable marine predators rather than just the prey of arthropods. Fish are abundant in most bodies of water and they can be found in nearly all aquatic environments, from high mountain streams to the abyssal and even hadal depths of the deepest oceans. With 33,100 described species, fish exhibit greater species diversity than any group of vertebrates. Fish are an important resource for humans worldwide, especially as food, commercial and subsistence fishers hunt fish in wild fisheries or farm them in ponds or in cages in the ocean. They are also caught by fishers, kept as pets, raised by fishkeepers. Fish have had a role in culture through the ages, serving as deities, religious symbols, fish do not represent a monophyletic group, and therefore the evolution of fish is not studied as a single event. Early fish from the record are represented by a group of small, jawless. Jawless fish lineages are mostly extinct, an extant clade, the lampreys may approximate ancient pre-jawed fish. The first jaws are found in Placodermi fossils, the diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth. It is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, fish may have evolved from a creature similar to a coral-like sea squirt, whose larvae resemble primitive fish in important ways. The first ancestors of fish may have kept the form into adulthood. Fish are a group, that is, any clade containing all fish also contains the tetrapods
35.
Marine mammal
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Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and they do not represent a distinct taxon or systematic grouping, but rather have a polyphyletic relation due to convergent evolution. They are also unified by their reliance on the environment for feeding. Marine mammal adaptation to an aquatic lifestyle vary considerably between species, both cetaceans and sirenians are fully aquatic and therefore are obligate water dwellers. Seals and sea-lions are semiaquatic, they spend the majority of their time in the water, in contrast, both otters and the polar bear are much less adapted to aquatic living. Their diet varies considerably as well, some may eat zooplankton, others may eat fish, squid, shellfish, sea-grass and this role in maintaining ecosystems makes them of particular concern as 23% of marine mammal species are currently threatened. Marine mammals were first hunted by aboriginal peoples for food and other resources, many were also the target for commercial industry, leading to a sharp decline in all populations of exploited species, such as whales and seals. Commercial hunting lead to the extinction of †Stellers sea cow and the monk seal. Other than hunting, marine mammals can be killed as bycatch from fisheries, increased ocean traffic causes collisions between fast ocean vessels and large marine mammals. Habitat degradation also threatens marine mammals and their ability to find, noise pollution, for example, may adversely affect echolocating mammals, and the ongoing effects of global warming degrade arctic environments. Marine mammals form a group of 129 species that rely on the ocean for their existence. They do not represent a taxon or systematic grouping. They are also unified by their reliance on the environment for feeding. The level of dependence on the environment for existence varies considerably with species. For example, dolphins and whales are completely dependent on the environment for all stages of their life, seals feed in the ocean but breed on land. Twenty three percent of mammal species are threatened. Five of these lineages are extinct, despite the diversity in morphology seen between groups, improving foraging efficiency has been the main driver in the evolution in these lineages. Today, fully aquatic marine mammals belong to one of two orders, Cetartiodactyla or Sirenia, based on molecular and morphological research, the cetaceans genetically and morphologically fall firmly within the Artiodactyla
36.
Commercial fishing
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Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the earth, large-scale commercial fishing is also known as industrial fishing. This profession has gained in popularity with the development of such as Deadliest Catch, Swords. The major fishing industries are not only owned by major corporations, the industry has had to adapt through the years in order to keep earning a profit. A study taken on some small family-owned commercial fishing companies showed that they adapted to continue to earn a living but not necessarily make a large profit. Commercial fishermen harvest a variety of animals, ranging from tuna, cod, carp, and salmon to shrimp, krill, lobster, clams, squid. There are large and important fisheries worldwide for species of fish, mollusks, crustaceans. However, a small number of species support the majority of the worlds fisheries. Some of these species are herring, cod, anchovy, tuna, flounder, mullet, squid, shrimp, salmon, crab, lobster, oyster and scallops. All except these last four provided a catch of well over a million tonnes in 1999, with herring. Many other species are fished in smaller numbers, commercial fishing may offer an abundance of jobs, but the pay varies from boat to boat, season to season. That may be true, but there are also the boats who dont do well, a 2009 paper in Science estimates, for the first time, the total world fish biomass as somewhere between 0.8 and 2.0 billion tonnes. Sustainability of fisheries is improved by using equipment that eliminates or minimizes catching non-targeted species. Fishing methods vary according to the region, the species being fished for, a commercial fishing enterprise may vary from one man with a small boat with hand-casting nets or a few pot traps, to a huge fleet of trawlers processing tons of fish every day. Billions of dollars are spent each year in researching/developing new techniques to reduce the injury, in fact, there was a study taken in 2000 on different deterrents and how effective they are at deterring the target species. The study showed that most auditory deterrents helped prevent whales from being caught while more physical barriers helped prevent birds from getting tangled within the net. During 2000–2006, commercial fishing was one of the most dangerous occupations in the United States, falling overboard specifically killed 182 fishermen in the period between 2000 and 2010. This fatality rate is 3 times that of the next most dangerous job in the U. S. also, between the years of 1919 and 2005,4111 fishermen died in fishing related accidents in the United Kingdom industry alone
37.
Orange roughy
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The orange roughy, red roughy, slimehead, or deep sea perch is a relatively large deep-sea fish belonging to the slimehead family. The UK Marine Conservation Society has categorized orange roughy as vulnerable to exploitation and it is found in 3 to 9 °C, deep waters of the Western Pacific Ocean, eastern Atlantic Ocean, Indo-Pacific, and in the Eastern Pacific off Chile. The orange roughy is notable for its lifespan, living for up to 149 years. It is important to commercial deep-trawl fisheries, the fish is a bright, brick-red color, fading to a yellowish-orange after death. Like other slimeheads, orange roughy is slow-growing and late to mature, many stocks became severely depleted within 3–20 years, but several have subsequently recovered. The orange roughy is not a vertically slender fish and its rounded head is riddled with muciferous canals, as is typical of slimeheads. The single dorsal fin contains four to six spines and 15 to 19 soft rays, the 19 to 25 ventral scutes form a hard, bony median ridge between the pelvic fins and anus. The pectoral fins contain 15-18 soft rays each, the fins are thoracic and contain one spine and six soft rays. The interior of the mouth and gill cavity is a bluish black, the scales are ctenoid and adherent. The lateral line is uninterrupted, with 28 to 32 scales whose spinules or ctenii largely obscure the lateral lines pores, the orange roughy is the largest known slimehead species at a maximum standard length of 75 cm and a maximum weight of 7 kg. The average commercial catch size is commonly between 35 and 45 centimetres in length, again, varying by area. Orange roughy are generally sluggish and demersal, they form aggregations with a population density of up to 2.5 fish per m2. These aggregations form in and around structures, such as undersea canyons and seamounts. The aggregations are not necessarily for spawning or feeding, the fish are thought to cycle through metabolic phases and they lose almost all pigmentation while inactive, when they are very approachable. Predators include large, deep-roving sharks, cutthroat eels, merluccid hakes, the diet of the orange roughy is depth-related, with adult diets inversely related to that of juveniles. For example, juvenile consumption of crustaceans is lowest at 900 metres but increases with depth while crustaceans in the adult diet peaks at 800–1,000 metres and decreases with depth, the consumption of fish is the opposite, juvenile consumption decreases with depth while adult consumption increases. This inverse feeding pattern may be an example of resource-partitioning to avoid competition for the available food at depths where prey is less abundant. The orange roughys metabolic phases are thought to be related to variations in prey concentrations
38.
Bottom trawling
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Bottom trawling is trawling along the sea floor. It is also referred to as dragging, the scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towing a net at the bottom of the ocean. Bottom trawling can be contrasted with midwater trawling, where a net is towed higher in the water column, Trawling is done by a trawler, which can be a small open boat with only 30 hp or a large factory trawler with 10,000 hp. Bottom trawling can be carried out by one trawler or by two trawlers fishing cooperatively, an early reference to fishery conservation measures comes from a complaint about a form of trawling dating from the 14th century, during the reign of Edward III. A petition was presented to Parliament in 1376 calling for the prohibition of a subtlety contrived instrument called the wondyrchoum, until the late 18th century sailing vessels were only capable of towing small trawls. However, in the years of that century a type of vessel emerged that was capable of towing a large trawl. The development of type of craft, the sailing trawler, is credited to the fishermen of Brixham in Devon. The new method proved to be far more efficient than traditional long-lining, at first its use was confined to the western half of the English Channel, but as the Brixham men extended their range to the North Sea and Irish Sea it became the norm there too. By the end of the 19th century there were more than 3,000 sailing trawlers in commission in UK waters, despite the availability of steam, trawling under sail continued to be economically efficient, and sailing trawlers continued to be built until the middle of the 1920s. Some were still operating in UK waters until the outbreak of World War II, and in Scandinavia, English commissions in the 19th century determined that there should be no limitation on trawling. They believed that bottom trawling, like tilling of land, actually increased production, as evidence, they noted that a second trawler would often follow a first trawler, and that the second trawler would often harvest even more fish than the first. Bottom trawling has been implicated in the population collapse of a variety of fish species, locally and worldwide, including orange roughy, barndoor skate, shark. The size and design of net used is determined by the species being targeted and this method is mainly used on smaller vessels, fishing for flatfish or prawns, relatively close inshore. Otter trawling derives its name from the large rectangular otter boards which are used to keep the mouth of the net open. They also act like a plough, digging up to 15 cm into the seabed, creating a turbid cloud, the net is held open vertically on an otter trawl by floats and/or kites attached to the headline, and weighted bobbins attached to the foot rope. These bobbins can also be designed to lift the net off the seabed when they hit an obstacle and these are known as rock-hopper gear. The body of the trawl is funnel-like, wide at its mouth and narrowing towards the cod end and it is long enough to assure adequate flow of water and prevent fish from escaping the net, after having been caught
39.
Bathymetry
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Bathymetry is the study of underwater depth of lake or ocean floors. In other words, bathymetry is the equivalent to hypsometry or topography. The name comes from Greek βαθύς, deep, and μέτρον, Bathymetric maps may also use a Digital Terrain Model and artificial illumination techniques to illustrate the depths being portrayed. The global bathymetry is combined with topography data to yield a Global Relief Model. Paleobathymetry is the study of past underwater depths, originally, bathymetry involved the measurement of ocean depth through depth sounding. Early techniques used pre-measured heavy rope or cable lowered over a ships side and this technique measures the depth only a singular point at a time, and is therefore inefficient. It is also subject to movements of the ship and currents moving the line out of true and therefore is inaccurate. The amount of time it takes for the sound or light to travel through the water, bounce off the seafloor, lIDAR/LADAR surveys are usually conducted by airborne systems. Starting in the early 1930s, single-beam sounders were used to make bathymetry maps, today, multibeam echosounders are typically used, which use hundreds of very narrow adjacent beams arranged in a fan-like swath of typically 90 to 170 degrees across. The tightly packed array of narrow individual beams provides very high angular resolution, in general a wide swath, which is depth dependent, allows a boat to map more seafloor in less time than a single-beam echosounder by making fewer passes. The beams update many times per second, allowing faster boat speed while maintaining 100% coverage of the seafloor, attitude sensors allow for the correction of the boats roll and pitch on the ocean surface, and a gyrocompass provides accurate heading information to correct for vessel yaw. A boat-mounted Global Positioning System positions the soundings with respect to the surface of the earth, sound speed profiles of the water column correct for refraction or ray-bending of the sound waves owing to non-uniform water column characteristics such as temperature, conductivity, and pressure. A computer system processes all the data, correcting for all of the factors as well as for the angle of each individual beam. The resulting sounding measurements are processed either manually, semi-automatically or automatically to produce a map of the area. As of 2010 a number of different outputs are generated, including a sub-set of the measurements that satisfy some conditions or integrated Digital Terrain Models. Historically, selection of measurements was more common in hydrographic applications while DTM construction was used for engineering surveys, geology, flow modeling, 2003–2005, DTMs have become more accepted in hydrographic practice. Satellites are also used to measure bathymetry, satellite radar maps deep-sea topography by detecting the subtle variations in sea level caused by the gravitational pull of undersea mountains, ridges, and other masses. On average, sea level is higher over mountains and ridges than over abyssal plains, coastal bathymetry data is available from NOAAs National Geophysical Data Center, which is now merged into National Centers for Environmental Information
40.
Altimeter
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An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, altitude can be determined based on the measurement of atmospheric pressure. The greater the altitude, the lower the pressure, when a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is called a pressure altimeter or barometric altimeter. A pressure altimeter is the altimeter found in most aircraft, hikers and mountain climbers use wrist-mounted or hand-held altimeters, in addition to other navigational tools such as a map, magnetic compass, or GPS receiver. The calibration of an altimeter follows the equation z = c T log , where c is a constant, T is the temperature, P is the pressure at altitude z. The constant c depends on the acceleration of gravity and the mass of the air. A barometric altimeter, used along with a map, can help to verify ones location. An altimeter is the most important piece of skydiving equipment, after the parachute itself, altitude awareness is crucial at all times during the jump, and determines the appropriate response to maintain safety. This is the most basic and common type, and is used by all student skydivers. The common design has a face marked from 0 to 4000m, the face plate sports sections prominently marked with yellow and red respectively, signifying the recommended deployment altitude, as well as emergency procedure decision altitude. Some advanced electronic altimeters are also available which use of the familiar analogue display. Digital visual altimeters, mounted on the wrist or hand and this type always operates electronically, and conveys the altitude as a number, rather than a pointer on a dial. An electronic altimeter is turned on on the ground before jump, if the intended landing zone is at a different elevation than the takeoff point, the user needs to input the appropriate offset by using a designated function. These are inserted into ones helmet, and emit a warning tone at a predefined altitude, audibles are strictly auxiliary devices, and do not replace, but complement a visual altimeter which remains the primary tool for maintaining altitude awareness. Audibles are not recommended and often banned from use by student skydivers and these do not show the precise altitude, but rather help maintain a general indicator in ones peripheral vision. The exact choice of altimeters depends heavily on the individual preferences, experience level, primary disciplines. On one end of the spectrum, a demonstration jump with water landing and no free fall might waive the mandated use of altimeters. Another skydiver doing similar types of jumps might wear a digital altimeter for their primary visual one, in aircraft, an aneroid barometer measures the atmospheric pressure from a static port outside the aircraft
41.
Tsunami
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A tsunami or tidal wave, also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Unlike normal ocean waves which are generated by wind, or tides which are generated by the pull of the Moon and Sun. Tsunami waves do not resemble normal undersea currents or sea waves, Tsunamis generally consist of a series of waves with periods ranging from minutes to hours, arriving in a so-called internal wave train. Wave heights of tens of metres can be generated by large events, numerous terms are used in the English language to describe waves created in a body of water by the displacement of water, however, none of the terms in frequent use are entirely accurate. The term tsunami, meaning harbour wave in literal translation, comes from the Japanese 津波, while not entirely accurate, as tsunami are not restricted to harbours, tsunami is currently the term most widely accepted by geologists and oceanographers. Tsunami are sometimes referred to as tidal waves and this once-popular term derives from the most common appearance of tsunami, which is that of an extraordinarily high tidal bore. Although the meanings of tidal include resembling or having the form or character of the tides, use of the tidal wave is discouraged by geologists. The term seismic sea wave also is used to refer to the phenomenon, prior to the rise of the use of the term tsunami in English-speaking countries, scientists generally encouraged the use of the term seismic sea wave rather than tidal wave. The Sumatran region is not unused to tsunamis either, with earthquakes of varying magnitudes regularly occurring off the coast of the island, Tsunamis are an often underestimated hazard in the Mediterranean Sea and parts of Europe. The tsunami claimed more than 123,000 lives in Sicily, the Storegga Slide in the Norwegian sea and some examples of tsunamis affecting the British Isles refer to landslide and meteotsunamis predominantly and less to earthquake-induced waves. The cause, in my opinion, of this phenomenon must be sought in the earthquake, at the point where its shock has been the most violent the sea is driven back, and suddenly recoiling with redoubled force, causes the inundation. Without an earthquake I do not see how such an accident could happen, the principal generation mechanism of a tsunami is the displacement of a substantial volume of water or perturbation of the sea. This displacement of water is attributed to either earthquakes, landslides, volcanic eruptions, glacier calvings or more rarely by meteorites. The waves formed in this way are then sustained by gravity, tides do not play any part in the generation of tsunamis. Tsunami can be generated when the sea floor abruptly deforms and vertically displaces the overlying water and they grow in height when they reach shallower water, in a wave shoaling process described below. A tsunami can occur in any state and even at low tide can still inundate coastal areas. On April 1,1946, the 8.6 Mw Aleutian Islands earthquake occurred with a maximum Mercalli intensity of VI and it generated a tsunami which inundated Hilo on the island of Hawaii with a 14-metre high surge. Between 165 and 173 were killed, the area where the earthquake occurred is where the Pacific Ocean floor is subducting under Alaska
42.
Oceanic basin
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In hydrology, an oceanic basin may be anywhere on Earth that is covered by seawater, but geologically ocean basins are large geologic basins that are below sea level. Older references consider the oceanic basins to be the complement to the continents, with dominating the latter. Earth is the known planet in the solar system where hypsography is characterized by different kinds of crust, oceanic crust. Oceans cover 70% of the Earths surface, because oceans lie lower than continents, the former serve as sedimentary basins that collect sediment eroded from the continents, known as clastic sediments, as well as precipitation sediments. Ocean basins also serve as repositories for the skeletons of carbonate- and silica-secreting organisms such as reefs, diatoms, radiolarians. Geologically, a basin may be actively changing size or may be relatively, tectonically inactive. The elements of an active - and growing - oceanic basin include an elevated mid-ocean ridge, the elements of an active oceanic basin often include the oceanic trench associated with a subduction zone. The Atlantic ocean and the Arctic ocean are good examples of active, growing oceanic basins, the Pacific Ocean is also an active, shrinking oceanic basin, even though it has both spreading ridge and oceanic trenches. Perhaps the best example of an oceanic basin is the Gulf of Mexico. The Aleutian Basin is another example of an inactive oceanic basin. The Japan Basin in the Sea of Japan which formed in the Miocene, is still active although recent changes have been relatively mild. List of abyssal plains and oceanic basins List of oceanic landforms Solid Earth Wright, John et al
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Oceanic crust
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Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate. The crust overlies the solidified and uppermost layer of the mantle, the crust and the solid mantle layer together constitute oceanic lithosphere. Oceanic crust is the result of erupted mantle material originating from below the plate, cooled and in most instances and this occurs mostly at mid-ocean ridges, but also at scattered hotspots, and also in rare but powerful occurrences known as flood basalt eruptions. It is primarily composed of rocks, or sima, which is rich in iron. Although a complete section of oceanic crust has not yet been drilled, Oceanic crust is significantly simpler than continental crust and generally can be divided in three layers. Layer 1 is on an average 0.4 km thick and it consists of unconsolidated or semiconsolidated sediments, usually thin or even not present near the mid-ocean ridges but thickens farther away from the ridge. Layer 3 is formed by slow cooling of magma beneath the surface and consists of coarse grained gabbros and it constitutes over two-thirds of oceanic crust volume with almost 5 km thickness. The most voluminous volcanic rocks of the floor are the mid-oceanic ridge basalts. These rocks have low concentrations of large ion lithophile elements, light rare earth elements, volatile elements, there can be found basalts enriched with incompatible elements, but they are rare and associated with mid-ocean ridge hot spots such as surroundings of Galapagos Islands, the Azores and Iceland. Oceanic crust is continuously being created at mid-ocean ridges, as plates diverge at these ridges, magma rises into the upper mantle and crust. As it moves away from the ridge, the lithosphere becomes cooler and denser, the youngest oceanic lithosphere is at the oceanic ridges, and it gets progressively older away from the ridges. As the mantle rises it cools and melts, as the pressure decreases, the amount of melt produced depends only on the temperature of the mantle as it rises. Hence most oceanic crust is the same thickness, an example of this is the Gakkel Ridge under the Arctic Ocean. Thicker than average crust is found above plumes as the mantle is hotter and hence it crosses the solidus and melts at a depth, creating more melt. An example of this is Iceland which has crust of thickness ~20 km, the oceanic lithosphere subducts at what are known as convergent boundaries. These boundaries can exist between oceanic lithosphere on one plate and oceanic lithosphere on another, or between oceanic lithosphere on one plate and continental lithosphere on another, in the second situation, the oceanic lithosphere always subducts because the continental lithosphere is less dense. The subduction process consumes older oceanic lithosphere, so oceanic crust is more than 200 million years old. The process of super-continent formation and destruction via repeated cycles of creation and destruction of oceanic crust is known as the Wilson cycle, the oldest large scale oceanic crust is in the west Pacific and north-west Atlantic - both are about up to 180-200 million years old
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Mid-ocean ridge
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A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
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Mantle plume
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A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the Earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from plate boundaries, for example. Others represent unusually large-volume volcanism, whether on plate boundaries, e. g. Iceland, a mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earths mantle becoming a diapir in the Earths crust. The currently active volcanic centers are known as hot spots, the hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes, another hypothesis for unusual volcanic regions is the Plate model. In 1971, geophysicist W. Jason Morgan proposed the hypothesis of mantle plumes, in this hypothesis, convection in the mantle transports heat from the core to the Earths surface in thermal diapirs. The latter type of convection is postulated to be independent of plate motions, the sizes and occurrence of mushroom mantle plumes can be predicted easily by transient instability theory developed by Tan and Thorpe. The theory predicts mushroom mantle plumes of about 2000 km diameter with a time of about 830 Myr for a core mantle heat flux of 20 mW/m2. The number of mantle plumes is predicted to be about 17, the plume hypothesis was studied using laboratory experiments conducted in small fluid-filled tanks in the early 1970s. Thermal or compositional fluid-dynamical plumes produced in that way were presented as models for the much larger postulated mantle plumes, the entire structure is considered to resemble a mushroom. The bulbous head of thermal plumes forms because hot material moves upward through the faster than the plume itself rises through its surroundings. In the late 1980s and early 1990s, experiments with thermal models showed that as the bulbous head expands it may entrain some of the adjacent mantle into the head. When a plume head encounters the base of the lithosphere, it is expected to flatten out against this barrier and it may then erupt onto the surface. Numerical modelling predicts that melting and eruption will take place several million years. These eruptions have been linked to flood basalts, although many of those erupt over much shorter time scales, flood basalts in the oceans are known as oceanic plateaus, and include the Ontong Java plateau of the western Pacific Ocean and the Kerguelen Plateau of the Indian Ocean. As the overlying tectonic plate moves over this hot spot, the eruption of magma from the fixed conduit onto the surface is expected to form a chain of volcanoes that parallels plate motion, the Hawaiian Islands chain in the Pacific Ocean is the type example. The eruption of continental flood basalts is often associated with continental rifting and this has led to the hypothesis that mantle plumes contribute to continental rifting and the formation of ocean basins. In the context of the alternative Plate model, continental breakup is an integral to plate tectonics
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Island arc
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An island arc is a type of archipelago, often composed of a chain of volcanoes, with arc-shaped alignment, situated parallel and close to a boundary between two converging tectonic plates. Most of these island arcs are formed as one oceanic plate subducts another one and. For example, large parts of the Andes/Central American/Canadian mountain chain may be known as a volcanic arc, on the other hand, the Aegean or Hellenic arc in the Mediterranean area, composed of numerous islands such as Crete, is an island arc, but is not volcanic. Parallel to it is the South Aegean Volcanic Arc, which is the island arc of the same tectonic system. There is some debate about the usefulness of the distinction between island arcs and volcanic arcs, the term volcanic island arc is merely a sub-classification of island arc. Island arcs are tectonically created arc-shaped mountain belts that are partly below sea level, essentially, they represent a specific geographic-topographic situation in which a mountain belt is partly submerged in ocean. Many of these are composed of volcanoes, and can thus be classified as volcanic island arcs. This process, called flux melting, generates low-density calc-alkaline magma that rises to intrude. The resulting volcano chain has the shape of an arc parallel to the convergent plate boundary, on the subducting side of the island arc is a deep and narrow oceanic trench, which is the trace at the Earth’s surface of the boundary between the downgoing and overriding plates. This trench is created by the pull of the relatively dense subducting plate pulling the leading edge of the plate downward. Multiple earthquakes occur along this boundary with the seismic hypocenters located at increasing depth under the island arc. Ocean basins that are being reduced by subduction are called remnant oceans as they will slowly be shrunken out of existence and this process has happened repeatedly in the geological history of the Earth. Insular Islands Intermontane Islands Back-arc basin High island Volcanic arc
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Arctic Ocean
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The Arctic Ocean is the smallest and shallowest of the worlds five major oceans. Alternatively, the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean, located mostly in the Arctic north polar region in the middle of the Northern Hemisphere, the Arctic Ocean is almost completely surrounded by Eurasia and North America. It is partly covered by sea ice throughout the year and almost completely in winter, the summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center uses satellite data to provide a record of Arctic sea ice cover. The Arctic may become ice free for the first time in human history within a few years or by 2040, for much of European history, the north polar regions remained largely unexplored and their geography conjectural. He was probably describing loose sea ice known today as growlers or bergy bits, his Thule was probably Norway, early cartographers were unsure whether to draw the region around the North Pole as land or water. The makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank and this lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an Open Polar Sea was persistent, john Barrow, longtime Second Secretary of the British Admiralty, promoted exploration of the region from 1818 to 1845 in search of this. In the United States in the 1850s and 1860s, the explorers Elisha Kane, even quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea. Nevertheless, as all the explorers who travelled closer and closer to the reported, the polar ice cap is quite thick. Fridtjof Nansen was the first to make a crossing of the Arctic Ocean. The first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard, with air support. The first nautical transit of the pole was made in 1958 by the submarine USS Nautilus. Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean, scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes. In World War II, the European region of the Arctic Ocean was heavily contested, the Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2, almost the size of Antarctica. The coastline is 45,390 km long and it is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands. It is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea, countries bordering the Arctic Ocean are, Russia, Norway, Iceland, Greenland, Canada and the United States. There are several ports and harbours around the Arctic Ocean In Alaska, in Canada, ships may anchor at Churchill in Manitoba, Nanisivik in Nunavut, Tuktoyaktuk or Inuvik in the Northwest territories
. PMID 19127302. Retrieved December 3, 2009.
