1.
Abyssal plain
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An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 metres and 6,000 metres. Lying generally between the foot of a rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest and least explored regions on Earth, Abyssal plains are key geologic elements of oceanic basins. In addition to elements, active oceanic basins also typically include an oceanic trench. Abyssal plains were not recognized as distinct physiographic features of the sea floor until the late 1940s and, until very recently and they are poorly preserved in the sedimentary record, because they tend to be consumed by the subduction process. The creation of the plain is the end result of spreading of the seafloor. Magma rises from above the asthenosphere and as this material reaches the surface at mid-ocean ridges it forms new oceanic crust. This is constantly pulled sideways by spreading of the seafloor, Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channelled from the continental margins along submarine canyons down into deeper water, the remainder of the sediment is composed chiefly of pelagic sediments. Metallic nodules are common in areas of the plains, with varying concentrations of metals, including manganese, iron, nickel, cobalt. These nodules may provide a significant resource for future mining ventures, owing in part to their vast size, abyssal plains are currently believed to be a major reservoir of biodiversity. The abyss also exerts significant influence upon ocean carbon cycling, dissolution of calcium carbonate, the structure and function of abyssal ecosystems are strongly influenced by the rate of flux of food to the seafloor and the composition of the material that settles. Factors such as change, fishing practices, and ocean fertilization are expected to have a substantial effect on patterns of primary production in the euphotic zone. This will undoubtedly impact the flux of material to the abyss in a similar manner and thus have a profound effect on the structure, function. The ocean can be conceptualized as being divided into zones, depending on depth. Photosynthesis in turn requires energy from sunlight to drive the chemical reactions that produce organic carbon, the stratum of the water column nearest the surface of the ocean is referred to as the photic zone. The photic zone can be subdivided into two different vertical regions, the uppermost portion of the photic zone, where there is adequate light to support photosynthesis by phytoplankton and plants, is referred to as the euphotic zone. The lower portion of the zone, where the light intensity is insufficient for photosynthesis, is called the dysphotic zone
2.
Abyssal (EP)
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Abyssal is an EP by the Japanese screamo band Envy. Abyssal likens itself with Insomniac Dozes more atmospheric sound, recorded and mixed at Bazooka Higashinakano, Spring 2007. Includes booklet with lyrics in both Japanese & English
3.
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
4.
Photic zone
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The photic zone, euphotic zone, or sunlight or zone is the depth of the water in a lake or ocean that is exposed to such intensity of sunlight which designates compensation point, i. e. It extends from the surface down to a depth where light intensity falls to one percent of that at the surface, accordingly, its thickness depends on the extent of light attenuation in the water column. Typical euphotic depths vary from only a few centimetres in highly turbid eutrophic lakes and it also varies with seasonal changes in turbidity. About 90% of all marine life lives in the photic zone, a small amount of primary production is generated deep in the abyssal zone around the hydrothermal vents which exist along some mid-oceanic ridges. The zone which extends from the base of the zone to about 200 metres is sometimes called the disphotic zone. While there is light, it is insufficient for photosynthesis. The euphotic zone together with the disphotic zone coincides with the epipelagic zone, the bottommost zone, below the euphotic zone, is called the aphotic zone. Most deep ocean waters belong to this zone, the transparency of the water, which determines the depth of the photic zone, is measured simply with a Secchi disk. It may also be measured with a photometer lowered into the water, electromagnetic absorption by water Epipelagic fish
5.
Mesopelagic zone
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The mesopelagic is that part of the pelagic zone that extends from a depth of 200 to 1000 metres below the ocean surface. It lies between the photic epipelagic above and the aphotic bathypelagic below, where there is no light at all, although some light penetrates the mesopelagic zone, it is insufficient for photosynthesis. The general types of forms found are daytime visiting herbivores, detritivores feeding on dead organisms and fecal pellets. Examples of animals in the zone are, bristlemouth, swordfish, squid, wolf eels, cuttlefish. The bristlemouth is the Earths most abundant vertebrate, numbering in the hundreds of trillions to quadrillions, the small amount of sunlight is sufficient for animals, such as the chain catshark, to be fluorescent. As of 2015 its small commercial fishery targeted meal, oil, the quantity of mesopelagic life is large enough to play a significant role in global carbon cycling. As the fish participate in the chain, they acquire carbon rendered from carbon dioxide absorbed by surface waters. Upon death, they transport that carbon into the abyss, as of 2015 the revised estimates of mesopelagic life had yet to be incorporated into climate models
6.
Bathyal zone
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The bathyal zone or bathypelagic – from Greek βαθύς, deep – is the part of the pelagic zone that extends from a depth of 1000 to 4000 meters below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below, the average temperature hovers at about 4 °C. Although larger by volume than the euphotic zone, the zone is less densely populated. Sunlight does not reach this zone, meaning primary production, if any, is almost nonexistent, there are no known plants because of the lack of sunlight necessary for photosynthesis. It is known as the zone because of this feature. Because of the lack of light, some species do not have eyes, however those possessing eyes in this include the viperfish. Many forms of live in the bathyal zone, such as squid, large whales. In the bathyal, some of the worlds largest whales feed, sponges, brachiopods, sea stars, and echinoids are also common in the bathyal zone. Animals in the zone are not threatened by predators that can see them. This zone is difficult for fish to live in, since it is hard to find nutrients. They have become very efficient, and many have slow metabolic rates to conserve energy. The fish are characterized by weak muscles, soft skin and slimy bodies, the adaptations of some of the fish that live there include small eyes and transparent skin. Except where the ocean is deep, the bathyal zone extends to the benthic zone on the ocean bed of that part of the continental slope that lies between 1000 and 4000 meters deep. The bathyal zone contains sharks, squid, octopuses, and many different species of fish, bathyal zones on the Mediterranean continental slope, An attempt. Research on marine benthos, 9th Iberian Symposium on Studies of Marine Benthos
7.
Hadal zone
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The hadal zone, also known as the hadopelagic zone and composed of trench zones, is the delineation for the deepest trenches in the ocean. The hadal zone is found from a depth to the bottom of the ocean of around 6,000 to 11,000 metres and exists in long, in total there are 33 trenches and 13 troughs around the world—46 individual hadal habitats in total. All the trenches together occupy an area less than one-quarter of one percent of the entire seafloor, the hadal zone has low population and low diversity of marine life. It is believed that most life at this depth is sustained by marine snow or the chemical reactions around thermal vents, the low nutrient level, extreme pressure and lack of sunlight create hostile living conditions in which few species are able to exist. As no sunlight reaches this layer of the ocean, deep sea creatures have reduced eyesight, the most common organisms include jellyfish, viperfish, tube worms and sea cucumbers. The hadal zone can reach far below 6,000 meters deep, at such depths the pressure in the hadal zone exceeds 1,100 standard atmospheres. In 1960, Jacques Piccard and Don Walsh reached the bottom of the Mariana Trench, the deepest known trench on Earth, james Cameron also reached the bottom in 2012 using the Deepsea Challenger. Abyssal plain Deep sea Alan Jamieson, The hadal zone - life in the deepest oceans, forscher filmen lebende Fische in Rekordtiefe from Spiegel 10/09/2008 about an expedition filming fish at a depth of more than 7,000 m
8.
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
9.
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
10.
Stratification (water)
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These layers are normally arranged according to density, with the least dense water masses sitting above the more dense layers. Water stratification also creates barriers to nutrient mixing between layers and this can affect the primary production in an area by limiting photosynthetic processes. When nutrients from the benthos cannot travel up into the photic zone, lower primary production also leads to lower net productivity in waters. Stratification may be upset by turbulence and this creates mixed layers of water. Forms of turbulence may include surface friction, upwelling and downwelling. Marshall et al. suggest that baroclinic eddies may be an important factor in maintaining stratification, canfield ocean Cline Lake stratification Meromictic
11.
Halocline
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In oceanography, a halocline is a subtype of chemocline caused by a strong, vertical salinity gradient within a body of water. Because salinity affects the density of seawater, it can play a role in its vertical stratification, increasing salinity by one kg/m3 results in an increase of seawater density of around 0.7 kg/m3. In the midlatitudes, an excess of evaporation over precipitation leads to surface waters being saltier than deep waters, in such regions, the vertical stratification is due to surface waters being warmer than deep waters and the halocline is destabilizing. Such regions may be prone to salt fingering, a process results in the preferential mixing of salinity. In these regions, the halocline is important in allowing for the formation of sea ice, haloclines are also found in fjords, and poorly mixed estuaries where fresh water is deposited at the ocean surface. In the plot, one can discern three layers, About 50 m of low salinity water swimming on top of the ocean, the temperature is -1.8 °C, which is very near to the freezing point. This layer blocks heat transfer from the warmer, deeper levels into the sea ice, about 150 m of steeply rising salinity and increasing temperature. The deep layer with nearly constant salinity and slowly decreasing temperature, a halocline can be easily created and observed in a drinking glass or other clear vessel. A halocline is most commonly confused with a thermocline - a thermocline is an area within a body of water that marks a change in temperature. Haloclines are common in water-filled caves near the ocean, less dense fresh water from the land forms a layer over salt water from the ocean. For underwater cave explorers, this can cause the illusion of air space in caverns. Passing through the halocline tends to stir up the layers, thermocline - A cline based on difference in water temperature, Chemocline - A cline based on difference in water chemistry, Pycnocline - A cline based on difference in water density. Hypersaline lake Isopycnal Thermohaline circulation Osmotic power
12.
Thermocline
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A thermocline is a thin but distinct layer in a large body of fluid in which temperature changes more rapidly with depth than it does in the layers above or below. In the ocean, the thermocline divides the upper mixed layer from the deep water below. Factors that affect the depth and thickness of a thermocline include seasonal weather variations, latitude and local conditions, such as tides. Most of the energy of sunlight is absorbed in the first few centimeters at the oceans surface. Below this mixed layer, the temperature remains relatively stable over day/night cycles, the temperature of the deep ocean drops gradually with depth. As saline water does not freeze until it reaches −2.3 °C the temperature well below the surface is not far from zero degrees. It is semi-permanent in the tropics, variable in temperate regions and shallow to nonexistent in the polar regions, a layer of sea ice will act as an insulation blanket. Technically, this stems from a discontinuity in the acoustic impedance of water created by the sudden change in density. It gives the water an appearance of wrinkled glass that is used to obscure bathroom windows and is caused by the altered refractive index of the cold or warm water column. These same schlieren can be observed when hot air rises off the tarmac at airports or desert roads and is the cause of mirages, thermoclines can also be observed in lakes. In colder climates, this leads to a phenomenon called stratification, during the summer, warm water, which is less dense, will sit on top of colder, denser, deeper water with a thermocline separating them. The warm layer is called the epilimnion and the layer is called the hypolimnion. Because the warm water is exposed to the sun during the day, as winter approaches, the temperature of the surface water will drop as nighttime cooling dominates heat transfer. This process is aided by wind or any process that agitates the water. This effect also occurs in Arctic and Antarctic waters, bringing water to the surface which and this enriching of surface nutrients may produce blooms of phytoplankton, making these areas productive. As the temperature continues to drop, the water on the surface may get cold enough to freeze, a new thermocline develops where the densest water sinks to the bottom, and the less dense water rises to the top. Once this new stratification establishes itself, it lasts until the water warms enough for the turnover, which occurs after the ice melts. During this transition, a bar may develop
13.
Thermohaline circulation
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Thermohaline circulation is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, wind-driven surface currents travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes. This dense water then flows into the ocean basins, while the bulk of it upwells in the Southern Ocean, the oldest waters upwell in the North Pacific. Extensive mixing therefore takes place between the basins, reducing differences between them and making the Earths oceans a global system. On their journey, the water masses transport both energy and matter around the globe, as such, the state of the circulation has a large impact on the climate of the Earth. The thermohaline circulation is called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt. On occasion, it is used to refer to the overturning circulation. Moreover, temperature and salinity gradients can lead to circulation effects that are not included in the MOC itself. The movement of surface currents pushed by the wind is fairly intuitive, for example, the wind easily produces ripples on the surface of a pond. Thus the deep ocean—devoid of wind—was assumed to be perfectly static by early oceanographers, however, modern instrumentation shows that current velocities in deep water masses can be significant. In general ocean water velocities range from fractions of centimeters per second to more than 1 m/s in surface currents like the Gulf Stream. In the deep ocean, the predominant driving force is differences in density, caused by salinity, there is often confusion over the components of the circulation that are wind and density driven. Note that ocean currents due to tides are also significant in places, most prominent in relatively shallow coastal areas. There they are thought to facilitate mixing processes, especially diapycnal mixing. The density of water is not globally homogeneous, but varies significantly and discretely. Sharply defined boundaries exist between water masses which form at the surface, and subsequently maintain their own identity within the ocean, but these sharp boundaries are not to be imagined spatially but rather in a T-S-diagram where water masses are distinguished. They position themselves above or below each other according to their density, warm seawater expands and is thus less dense than cooler seawater. Saltier water is denser than water because the dissolved salts fill interstices between water molecules, resulting in more mass per unit volume
14.
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
15.
Lake stratification
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Lake stratification is the separation of lakes into three layers, Epilimnion, the top of the lake. Metalimnion, the layer, which may change depth throughout the day. The thermal stratification of lakes refers to a change in the temperature at different depths in the lake, cold water is denser than warm water and the epilimnion generally consists of water that is not as dense as the water in the hypolimnion. However, the temperature of maximum density for freshwater is 4 °C, for example, in dimictic lakes the lake water turns over during the spring and the fall. This process occurs slowly in deeper water and as a result. If the stratification of water lasts for extended periods, the lake is meromictic, conversely, for most of the time, the relatively shallower meres are unstratified, that is, the mere is considered all epilimnion. Natural resource and environmental managers are often challenged by problems caused by lake, fish die-offs have been directly associated with thermal gradients, stagnation, and ice cover. Excessive growth of plankton may limit the use of lakes. With severe thermal stratification in a lake, the quality of drinking water also can be adversely affected, one commonly used tool to reduce the severity of these lake management problems is to eliminate or lessen thermal stratification through aeration. Many types of equipment have been used to thermally destratify lakes. Aeration has met some success, although it has rarely proved to be a panacea. Lake Stratification in Lake Lanier and its effects on the Chattahoochee River Lackey, a technique for eliminating thermal stratification in lakes. Water Resources Bulletin, Journal of the American Water Resources Association, response of physical and chemical parameters to eliminating thermal stratification in a reservoir. Water Resources Bulletin, Journal of the American Water Resources Association, http, //onlinelibrary. wiley. com/doi/10. 1111/j. 1752-1688.1972. tb05181. x/abstract Lackey, Robert T. and Donald W. Holmes. Evaluation of two methods of aeration to prevent winterkill, density Stratification, part of an educational website Water on the Web operated by the University of Minnesota, Duluth. Aquatic Science Stratification Hypoxia Freshwater ecosystems Water column Lake aeration Aquatic Science Hypoxia Freshwater ecosystems Water column
16.
Aquatic ecosystem
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An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on other and on their environment live in aquatic ecosystems. The two main types of ecosystems are marine ecosystems and freshwater ecosystems. Marine ecosystems cover approximately 71% of the Earths surface and contain approximately 97% of the planets water and they generate 32% of the worlds net primary production. They are distinguished from freshwater ecosystems by the presence of dissolved compounds, especially salts, approximately 85% of the dissolved materials in seawater are sodium and chlorine. Seawater has a salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems, marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, the benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides, in this figure it is termed the littoral zone, other near-shore zones can include estuaries, salt marshes, coral reefs, lagoons and mangrove swamps. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web, classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals, cephalopods, echinoderms, and sharks. Fishes caught in marine ecosystems are the biggest source of commercial foods obtained from wild populations, environmental problems concerning marine ecosystems include unsustainable exploitation of marine resources, marine pollution, climate change, and building on coastal areas. Freshwater ecosystems cover 0. 78% of the Earths surface and inhabit 0. 009% of its total water and they generate nearly 3% of its net primary production. Freshwater ecosystems contain 41% of the known fish species. There are three types of freshwater ecosystems, Lentic, slow moving water, including pools, ponds. Lotic, faster moving water, for example streams and rivers, wetlands, areas where the soil is saturated or inundated for at least part of the time. Lake ecosystems can be divided into zones, one common system divides lakes into three zones. The first, the zone, is the shallow zone near the shore. This is where rooted wetland plants occur, the offshore is divided into two further zones, an open water zone and a deep water zone
17.
Wild fisheries
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A fishery is an area with an associated fish or aquatic population which is harvested for its commercial value. Fisheries can be marine or freshwater and they can also be wild or farmed. Wild fisheries are sometimes called capture fisheries, the aquatic life they support is not controlled in any meaningful way and needs to be captured or fished. Wild fisheries exist primarily in the oceans, and particularly around coasts and they also exist in lakes and rivers. Issues with wild fisheries are overfishing and pollution, significant wild fisheries have collapsed or are in danger of collapsing, due to overfishing and pollution. Overall, production from the wild fisheries has levelled out. As a contrast to wild fisheries, farmed fisheries can operate in sheltered waters, in rivers, lakes and ponds. Farmed fisheries are technological in nature, and revolve around developments in aquaculture, farmed fisheries are expanding, and Chinese aquaculture in particular is making many advances. Nevertheless, the majority of fish consumed by humans continues to be sourced from wild fisheries, as of the early 21st century, fish is humanitys only significant wild food source. This can be contrasted with 59.9 million tonnes produced in fish farms, worldwide, freshwater lakes have an area of 1.5 million square kilometres. Saline inland seas add another 1.0 million square kilometres, there are 28 freshwater lakes with an area greater than 5,000 square kilometres, totalling 1.18 million square kilometres or 79 percent of the total. Pollution is the introduction of contaminants into an environment, land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into the sea. Pollution from ships is also a problem, Marine debris is human-created waste that ends up floating in the sea. Oceanic debris tends to accumulate at the centre of gyres and coastlines, eighty percent of all known marine debris is plastic - a component that has been rapidly accumulating since the end of World War II. Discarded plastic bags, six rings and other forms of plastic waste which finish up in the ocean present dangers to wildlife. Aquatic life can be threatened through entanglement, suffocation, and ingestion, nurdles, also known as mermaids tears, are plastic pellets typically under five millimetres in diameter, and are a major contributor to marine debris. They are used as a raw material in manufacturing, and are thought to enter the natural environment after accidental spillages. Nurdles are also created through the weathering of larger plastic debris
18.
Greek language
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Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
19.
Giant tube worm
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Giant tube worms, Riftia pachyptila, are marine invertebrates in the phylum Annelida related to tube worms commonly found in the intertidal and pelagic zones. Riftia pachyptila live over a deep, and up to several miles deep, on the floor of the Pacific Ocean near black smokers. These worms can reach a length of 2.4 m, ambient temperature in their natural environment ranges from 2 to 30 degrees Celsius. The common name giant tube worm is also applied to the largest living species of shipworm, Kuphus polythalamia. Riftia develop from a free-swimming, pelagic, non-symbiotic trochophore larva, the symbiotic bacteria, on which adult worms depend for sustenance, are not present in the gametes, but are acquired from the environment via the digestive tract. The digestive tract transiently connects from a mouth at the tip of the medial process to a foregut, midgut, hindgut. They have a highly vascularized, red plume at the tip of their free end which is an organ for exchanging compounds with the environment, the tube worm does not have many predators. If threatened, the plume may be retracted into the protective tube. The plume provides essential nutrients to bacteria living inside the trophosome, tube worms have no digestive tract, but the bacteria convert oxygen, hydrogen sulfide, carbon dioxide, etc. into organic molecules on which their host worms feed. This process, known as chemosynthesis, was recognized within the trophosome by Colleen Cavanaugh, the bright red color of the plume structures results from several extraordinarily complex hemoglobins, which contain up to 144 globin chains. These tube worm hemoglobins are remarkable for carrying oxygen in the presence of sulfide, nitrate and nitrite are toxic, but nitrogen is required for biosynthetic processes. To transport nitrate to the bacteria, R. pachyptila concentrate nitrate in their blood, the exact mechanism of R. pachyptila’s ability to withstand and concentrate nitrate is still unknown. With sunlight not available directly as a form of energy, the tube worms rely on bacteria in their habitat to oxidize hydrogen sulfide and this reaction provides the energy needed for chemosynthesis. In this way tube worms are similar to forms of ocean life which live at depths that sunlight cannot penetrate. However, tube worms are unique in being able to use bacteria to obtain almost all the materials they need for growth from molecules dissolved in water. Some nutrients have to be filtered out of the water, tube worm growth resembles that of hydroponically grown fungi more than it does that of typical animals which need to eat. To reproduce, Riftia pachyptila females release lipid-rich eggs into the water so they start to float upwards. The males then unleash sperm bundles that swim to meet the eggs, after the eggs have hatched, the larvae swim down to attach themselves to the rock
20.
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
21.
Pacific Ocean
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The Pacific Ocean is the largest and deepest of the Earths oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west, the Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres. Both the center of the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean, the oceans current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means peaceful sea, important human migrations occurred in the Pacific in prehistoric times. Long-distance trade developed all along the coast from Mozambique to Japan, trade, and therefore knowledge, extended to the Indonesian islands but apparently not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality, from 1404 to 1433 Zheng He led expeditions into the Indian Ocean. The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and he named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. Later, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Castilian expedition of world circumnavigation starting in 1519, Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters. The ocean was often called the Sea of Magellan in his honor until the eighteenth century, sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, and Papua New Guinea. In 1542–43 the Portuguese also reached Japan, in 1564, five Spanish ships consisting of 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi and sailed to the Philippines and Mariana Islands. The Manila galleons operated for two and a half centuries linking Manila and Acapulco, in one of the longest trade routes in history, Spanish expeditions also discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, and the Admiralty Islands in the South Pacific. In the 16th and 17th century Spain considered the Pacific Ocean a Mare clausum—a sea closed to other naval powers, as the only known entrance from the Atlantic the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western end of the Pacific Ocean the Dutch threatened the Spanish Philippines, Spain also sent expeditions to the Pacific Northwest reaching Vancouver Island in southern Canada, and Alaska. The French explored and settled Polynesia, and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest, one of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789–1794. It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific. Growing imperialism during the 19th century resulted in the occupation of much of Oceania by other European powers, and later, Japan, in Oceania, France got a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853 respectively. After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro managed to negotiate an incorporation of the island into Chile with native Rapanui in 1888, by occupying Easter Island, Chile joined the imperial nations
22.
Giant squid
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The giant squid is a deep-ocean dwelling squid in the family Architeuthidae. The mantle is about 2 m long, and the length of the squid excluding its tentacles rarely exceeds 5 m, claims of specimens measuring 20 m or more have not been scientifically documented. The number of different giant squid species has been debated, in 2004, Japanese researchers took the first images of a live giant squid in its natural habitat, and in July 2012, a live adult was first filmed in its natural habitat off Chichi-jima. Like all squid, a giant squid has a mantle, eight arms, the arms and tentacles account for much of the squids great length, making it much lighter than its chief predator, the sperm whale. Scientifically documented specimens have masses of hundreds, rather than thousands, the inside surfaces of the arms and tentacles are lined with hundreds of subspherical suction cups,2 to 5 cm in diameter, each mounted on a stalk. The circumference of these suckers is lined with sharp, finely serrated rings of chitin, the perforation of these teeth and the suction of the cups serve to attach the squid to its prey. It is common to find circular scars from the suckers on or close to the head of sperm whales that have attacked giant squid, each tentacular club is divided into three regions – the carpus, manus and dactylus. The carpus has a cluster of cups, in six or seven irregular. The manus is broader, closer to the end of the club, the bases of all the arms and tentacles are arranged in a circle surrounding the animals single, parrot-like beak, as in other cephalopods. Giant squid have small fins at the rear of their mantles used for locomotion, like other cephalopods, they are propelled by jet – by pulling water into the mantle cavity, and pushing it through the siphon, in gentle, rhythmic pulses. They can also move quickly by expanding the cavity to fill it with water, Giant squid breathe using two large gills inside the mantle cavity. The circulatory system is closed, which is a characteristic of cephalopods. Like other squid, they contain dark ink used to deter predators, the giant squid has a sophisticated nervous system and complex brain, attracting great interest from scientists. It also has the largest eyes of any living creature except perhaps the colossal squid – up to at least 27 cm in diameter, large eyes can better detect light, which is scarce in deep water. The giant squid probably cannot see colour, but it can discern small differences in tone. Giant squid and some other large squid species maintain neutral buoyancy in seawater through an ammonium chloride solution which is found throughout their bodies and is lighter than seawater and this differs from the method of flotation used by most fish, which involves a gas-filled swim bladder. The solution tastes somewhat like salmiakki and makes giant squid unattractive for general human consumption, like all cephalopods, giant squid use organs called statocysts to sense their orientation and motion in water. The age of a giant squid can be determined by growth rings in the statocysts statolith, much of what is known about giant squid age is based on estimates of the growth rings and from undigested beaks found in the stomachs of sperm whales
23.
Pascal (unit)
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The pascal is the SI derived unit of pressure used to quantify internal pressure, stress, Youngs modulus and ultimate tensile strength. It is defined as one newton per square meter and it is named after the French polymath Blaise Pascal. Common multiple units of the pascal are the hectopascal which is equal to one millibar, the unit of measurement called standard atmosphere is defined as 101,325 Pa and approximates to the average pressure at sea-level at the latitude 45° N. Meteorological reports typically state atmospheric pressure in hectopascals, the unit is named after Blaise Pascal, noted for his contributions to hydrodynamics and hydrostatics, and experiments with a barometer. The name pascal was adopted for the SI unit newton per square metre by the 14th General Conference on Weights, one pascal is the pressure exerted by a force of magnitude one newton perpendicularly upon an area of one square metre. The unit of measurement called atmosphere or standard atmosphere is 101325 Pa and this value is often used as a reference pressure and specified as such in some national and international standards, such as ISO2787, ISO2533 and ISO5024. In contrast, IUPAC recommends the use of 100 kPa as a standard pressure when reporting the properties of substances, geophysicists use the gigapascal in measuring or calculating tectonic stresses and pressures within the Earth. Medical elastography measures tissue stiffness non-invasively with ultrasound or magnetic resonance imaging, in materials science and engineering, the pascal measures the stiffness, tensile strength and compressive strength of materials. In engineering use, because the pascal represents a small quantity. The pascal is also equivalent to the SI unit of energy density and this applies not only to the thermodynamics of pressurised gases, but also to the energy density of electric, magnetic, and gravitational fields. In measurements of sound pressure, or loudness of sound, one pascal is equal to 94 decibels SPL, the quietest sound a human can hear, known as the threshold of hearing, is 0 dB SPL, or 20 µPa. The airtightness of buildings is measured at 50 Pa, the units of atmospheric pressure commonly used in meteorology were formerly the bar, which was close to the average air pressure on Earth, and the millibar. Since the introduction of SI units, meteorologists generally measure pressures in hectopascals unit, exceptions include Canada and Portugal, which use kilopascals. In many other fields of science, the SI is preferred, many countries also use the millibar or hectopascal to give aviation altimeter settings. In practically all fields, the kilopascal is used instead. Centimetre of water Metric prefix Orders of magnitude Pascals law
24.
Pounds per square inch
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The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units. Now converting the psi to standard atmospheres,1 atm =101325 Pa =101325 Pa 6894.757293168 Pa / psi ≈14.70 psi Therefore,1 atmosphere is approximately 14.7 pounds per square inch. Pounds per square inch absolute is used to make it clear that the pressure is relative to a rather than the ambient atmospheric pressure. Since atmospheric pressure at sea level is around 14.7 psi, the converse is pounds per square inch gauge or pounds per square inch gage, indicating that the pressure is relative to atmospheric pressure. For example, a bicycle tire pumped up to 65 psi above atmospheric pressure. When gauge pressure is referenced to something other than ambient atmospheric pressure, the kilopound per square inch is a scaled unit derived from psi, equivalent to a thousand psi. Ksi are not widely used for gas pressures and they are mostly used in materials science, where the tensile strength of a material is measured as a large number of psi. The conversion in SI Units is 1 ksi =6.895 MPa, the megapound per square inch is another multiple equal to a million psi. It is used in mechanics for the modulus of the materials. The conversion in SI Units is 1 Mpsi =6.895 GPa, inch of water,0.036 psid Blood pressure – clinically normal human blood pressure,2.32 psig/1.55 psig Natural gas residential piped in for consumer appliance, 4–6 psig. Boost pressure provided by a turbocharger, 6–15 psig NFL football,12. 5–13.5 psig Atmospheric pressure at sea level,14
25.
Mariana Trench
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The Mariana Trench or Marianas Trench is the deepest part of the worlds oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands, the trench is about 2,550 kilometres long with an average width of 69 kilometres. At the bottom of the trench the water column above exerts a pressure of 1,086 bars, more than 1,000 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4. 96%, the temperature at the bottom is 1 to 4 °C. The trench is not the part of the seafloor closest to the center of the Earth and this is because the Earth is not a perfect sphere, its radius is about 25 kilometres less at the poles than at the equator. As a result, parts of the Arctic Ocean seabed are at least 13 kilometres closer to the Earths center than the Challenger Deep seafloor. Xenophyophores have been found in the trench by Scripps Institution of Oceanography researchers at a depth of 10.6 kilometres below the sea surface. On 17 March 2013, researchers reported data that suggested microbial life forms thrive within the trench, the Mariana Trench is named for the nearby Mariana Islands. The islands are part of the arc that is formed on an over-riding plate, called the Mariana Plate. The Mariana Trench is part of the Izu-Bonin-Mariana subduction system that forms the boundary between two tectonic plates, in this system, the western edge of one plate, the Pacific Plate, is subducted beneath the smaller Mariana Plate that lies to the west. The deepest area at the boundary is the Mariana Trench proper. The movement of the Pacific and Mariana plates is also responsible for the formation of the Mariana Islands. These volcanic islands are caused by melting of the upper mantle due to release of water that is trapped in minerals of the subducted portion of the Pacific Plate. The trench was first sounded during the Challenger expedition in 1875, using a weighted rope, in 1877, a map was published called Tiefenkarte des Grossen Ozeans by Petermann, which showed a Challenger Tief at the location of that sounding. In 1899, USS Nero, a collier, recorded a depth of 5,269 fathoms. In 1951, Challenger II surveyed the trench using echo sounding, during this survey, the deepest part of the trench was recorded when the Challenger II measured a depth of 5,960 fathoms at 11°19′N 142°15′E, known as the Challenger Deep. In 1957, the Soviet vessel Vityaz reported a depth of 11,034 metres at a location dubbed the Mariana Hollow, in 1962, the surface ship M. V. Spencer F. Baird recorded a depth of 10,915 metres using precision depth gauges
26.
Bathyscaphe
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The float is filled with gasoline because it is readily available, buoyant, and, for all practical purposes, incompressible. By contrast, the cabin must withstand a huge pressure differential and is massively built. Buoyancy at the surface can be trimmed easily by replacing gasoline with water, Auguste Piccard, inventor of the first bathyscaphe, composed the name bathyscaphe using the Ancient Greek words βαθύς bathys and σκάφος skaphos. For example, the pressure at the bottom of the Challenger Deep is more than seven times that in a standard H-type compressed gas cylinder, instead, ballast in the form of iron shot is released to ascend, the shot being lost to the ocean floor. The iron shot containers are in the form of one or more hoppers which are open at the bottom throughout the dive, the iron shot being held in place by an electromagnet at the neck. This is a device as it requires no power to ascend, in fact, in the event of a power failure, shot runs out by gravity. The first bathyscaphe was dubbed FNRS-2, named after the Fonds National de la Recherche Scientifique, propulsion was provided by battery-driven electric motors. The float held 37,850 litres of aviation gasoline, there was no access tunnel, the sphere had to be loaded and unloaded while on deck. The first journeys were detailed in the Jacques Cousteau book The Silent World, as described in the book, the vessel had serenely endured the pressure of the depths, but had been destroyed in a minor squall. FNRS-3 was a new submersible, using the crew sphere from the damaged FNRS-2, Piccards second bathyscaphe was actually a third vessel Trieste, which was purchased by the United States Navy from Italy in 1957. It had two water ballast tanks and eleven buoyancy tanks holding 120,000 litres of gasoline, in 1960 Trieste, carrying Piccards son Jacques Piccard and Lt. Don Walsh, reached the deepest known point on the Earths surface, the Challenger Deep, in the Mariana Trench. The onboard systems indicated a depth of 37,800 ft but this was corrected to 35,813 ft by taking into account variations arising from salinity. Later and more accurate measurements made in 1995 have found the Challenger Deep to be slightly shallower at 35,798 ft. The crew of the Trieste noted that the floor consisted of diatomaceous ooze and reported observing some type of flatfish, resembling a sole, in 1995, the Japanese sent an unmanned submersible to this depth, Kaikō, but it was later lost at sea. In 2009, a team from the Woods Hole Oceanographic Institution sent a submarine named Nereus to the bottom of the trench. On 25 March 2012, James Cameron reached the Challenger Deep in the Deepsea Challenger submersible, siphonophores and the Deep Scattering Layer. The US Navy account of the dive, with photographs Brewington, depth of the Deepest Dive in a Bathyscaphe. History of the Bathyscape Trieste FNRS-213,000 Feet Under the Sea in the French Bathyscaphe Popular Mechanics, May 1954, Deepsea Challenger – Mariana Trench Dive
27.
Bathyscaphe Trieste
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On 23 January 1960, Jacques Piccard and US Navy Lieutenant Don Walsh achieved the goal of Project Nekton. Trieste was the first manned vessel to have reached the bottom of the Challenger Deep, Trieste consisted of a float chamber filled with gasoline for buoyancy, with a separate pressure sphere to hold the crew. This configuration, allowed for a dive, rather than the previous bathysphere designs in which a sphere was lowered to depth. Trieste was designed by the Swiss scientist Auguste Piccard and originally built in Italy and his pressure sphere, composed of two sections, was built by the company Acciaierie Terni. The upper part was manufactured by the company Cantieri Riuniti dellAdriatico, in the Free Territory of Trieste, the installation of the pressure sphere was done in the Cantiere navale di Castellammare di Stabia, near Naples. Trieste was launched on 26 August 1953 into the Mediterranean Sea near the Isle of Capri, the design was based on previous experience with the bathyscaphe FNRS-2. Trieste was operated by the French Navy, after several years of operation in the Mediterranean Sea, the Trieste was purchased by the United States Navy in 1958 for $250,000. At the time of Project Nekton, Trieste was more than 15 m long, the pressure sphere provided just enough room for two people. Trieste was subsequently fitted with a new sphere, manufactured by the Krupp Steel Works of Essen, Germany. To withstand the pressure of 1.25 metric tons per cm² at the bottom of Challenger Deep. The sphere weighed 14.25 metric tons in air and 8 metric tons in water, outside illumination for the craft was provided by quartz arc-light bulbs, which proved to be able to withstand the over 1,000 standard atmospheres of pressure without any modification. Trieste departed San Diego on 5 October 1959 for Guam aboard the freighter Santa Maria to participate in Project Nekton, on 23 January 1960, she reached the ocean floor in the Challenger Deep, carrying Jacques Piccard and Don Walsh. This was the first time a vessel, manned or unmanned, had reached the deepest known point of the Earths oceans, the descent to the ocean floor took 4 hours 47 minutes at a descent rate of 0.9 metres per second. After passing 9,000 metres, one of the outer Plexiglas window panes cracked, the two men spent barely twenty minutes on the ocean floor. The temperature in the cabin was 7 °C at the time, while at maximum depth, Piccard and Walsh unexpectedly regained the ability to communicate with the support ship, USS Wandank, using a sonar/hydrophone voice communications system. While at the bottom, Piccard and Walsh observed a number of small sole and their claim the fish were swimming would prove at least some vertebrate life can withstand the extreme pressure at the oceans deepest point. They noted that the floor of the Challenger Deep consisted of diatomaceous ooze, the ascent took 3 hours and 15 minutes. Beginning in April 1963, Trieste was modified and used in the Atlantic Ocean to search for the missing submarine USS Thresher, Trieste was delivered to Boston Harbor by USS Point Defiance under the command of Captain H. H. Haisten
28.
Teleoperation
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Teleoperation indicates operation of a system or machine at a distance. It is similar in meaning to the remote control but is usually encountered in research, academic. It is most commonly associated with robotics and mobile robots but can be applied to a range of circumstances in which a device or machine is operated by a person from a distance. The term teleoperation is in use in research and technical communities as a term for referring to operation at a distance. This is as opposed to telepresence which is a standard term. The history of teleoperation can be traced back to the beginnings of radio communication, teleoperation is now moving into the hobby industry with first-person view equipment. FPV equipment mounted on cars, planes and helicopters give a TV-style transmission back to the operator. There are several types of systems that are often controlled remotely. Industrial machinery is operated remotely, particularly in hazardous environments. One notable example is in the construction of the Object Shelter or sarcophagus at Chernobyl after the Chernobyl accident, remotely operated vehicles are extensively used in hazardous environments. Remote surgery Unmanned aerial vehicles, also known as drones Telerobotics Remote manipulator Telecommand NASA Telerobotics
29.
Submarine
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A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability, the term most commonly refers to a large, crewed vessel. It is also used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine. The noun submarine evolved as a form of submarine boat, by naval tradition, submarines are usually referred to as boats rather than as ships. Although experimental submarines had been built before, submarine design took off during the 19th century, Submarines were first widely used during World War I, and now figure in many navies large and small. Civilian uses for submarines include marine science, salvage, exploration and facility inspection, Submarines can also be modified to perform more specialized functions such as search-and-rescue missions or undersea cable repair. Submarines are also used in tourism, and for undersea archaeology, most large submarines consist of a cylindrical body with hemispherical ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines, this structure is the sail in American usage, a conning tower was a feature of earlier designs, a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller at the rear, and various hydrodynamic control fins, smaller, deep-diving and specialty submarines may deviate significantly from this traditional layout. Submarines use diving planes and also change the amount of water, Submarines have one of the widest ranges of types and capabilities of any vessel. Submarines can work at greater depths than are survivable or practical for human divers, modern deep-diving submarines derive from the bathyscaphe, which in turn evolved from the diving bell. In 1578, the English mathematician William Bourne recorded in his book Inventions or Devises one of the first plans for an underwater navigation vehicle and its unclear whether he ever carried out his idea. The first submersible of whose construction there exists reliable information was designed and built in 1620 by Cornelis Drebbel and it was propelled by means of oars. By the mid-18th century, over a dozen patents for submarines/submersible boats had been granted in England, in 1747, Nathaniel Symons patented and built the first known working example of the use of a ballast tank for submersion. His design used leather bags that could fill with water to submerge the craft, a mechanism was used to twist the water out of the bags and cause the boat to resurface. In 1749, the Gentlemens Magazine reported that a design had initially been proposed by Giovanni Borelli in 1680. By this point of development, further improvement in design stagnated for over a century, until new industrial technologies for propulsion. The first military submarine was the Turtle, a hand-powered acorn-shaped device designed by the American David Bushnell to accommodate a single person and it was the first verified submarine capable of independent underwater operation and movement, and the first to use screws for propulsion
30.
Nereus (underwater vehicle)
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Nereus was a hybrid unmanned autonomous underwater vehicle built by the Woods Hole Oceanographic Institution. Constructed as a vehicle to operate at depths of up to 11,000 metres, it was designed to explore Challenger Deep. On 10 May 2014, Nereus was lost while exploring the Kermadec Trench at a depth of 9,900 metres, communications were cut off at around 2 p. m. local time, and debris retrieved later revealed that it imploded due to high pressure. Being a hybrid ROV means that the vehicle could operate untethered or tethered with an optic fiber cable. The latter enabled it to deep dives while being highly maneuverable. The optic fiber tether has the diameter of a human hair. It is made up of a layer of plastic surrounding a slender glass fiber core. The vehicle carried approximately 40 kilometers of cable wound in two small canisters that play out the fiber as the vehicle descends and this slim tether is smaller, lighter, and more cost effective than cable. Nereus weighed approximately 3 tons in air and was about 4.25 meters long and 2.3 meters wide, approximately 2,000 lithium-ion batteries provided its power. The vehicle made use of precisely designed ceramic spheres rather than the much heavier syntactic foam that is used for submersible vehicles. Each hull contained between 700 and 800 9-cm hollow spheres that were designed to handle intense pressure. Nereus had a robotic manipulator arm to conduct the sample collecting that operates hydraulically and was able to perform under intense pressure. As an alternative to the tether, the Nereus could be switched to a free-swimming mode and operated as an autonomous vehicle to survey the ocean floor. The Challenger Deep is located in the Western Pacific Ocean near the island of Guam in the Mariana Trench, the deepest known part of an ocean on earth, and the deepest known location on earth. The May 2009 dive by the Nereus achieved a depth of 10,902 metres, making it the worlds deepest-diving vehicle then in operation, to accomplish this dive, the vehicle had to sustain pressures over 1,000 times the atmospheric pressure at the Earths surface. It hovered over the trench for more than 10 hours and sent back live video to the mother ship, Nereus is the third vehicle in the world to reach the bottom of the Pacific Oceans Challenger Deep. The first was the manned Bathyscaphe Trieste, which carried U. S. Navy Lieutenant Don Walsh and Swiss engineer Jacques Piccard, as of 2012 this had been the only manned voyage to the Challenger Deep. The Nereus dive aimed for the same spot, on 24 March 1995 a Japanese robotic deep-sea probe called Kaikō made the first unmanned trip to the Challenger Deep
31.
Deepsea Challenger
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Deepsea Challenger is a 7. 3-metre deep-diving submersible designed to reach the bottom of Challenger Deep, the deepest-known point on Earth. On 26 March 2012, Canadian film director James Cameron piloted the craft to accomplish this goal in the second manned dive reaching the Challenger Deep. Deepsea Challenger was secretly built in Australia, in partnership with the National Geographic Society and with support from Rolex, the construction of the submersible was headed by Australian engineer Ron Allum. Many of the developer team members hail from Sydneys cave-diving fraternity including Allum himself with many years cave-diving experience. The foam is composed of small hollow glass spheres suspended in an epoxy resin. The foam supersedes gasoline-filled tanks for flotation as used in the historic submarine, Allum also built many innovations, necessary to overcome the limitations of existing products. Allum gained much of his developing the electronic communication used in Camerons Titanic dives in filming Ghosts of the Abyss, Bismarck. Power systems for the submarine were supplied by batteries that were housed within the foam. The lithium battery charging systems were designed by Ron Allum, the submersible contains over 180 onboard systems, including batteries, thrusters, life support, 3D cameras, and LED lighting. These interconnected systems are monitored and controlled by a programmable automation controller from Temecula, the crucial structural elements, such as the backbone and pilot sphere that carried Cameron, were engineered by the Tasmanian company Finite Elements. The submersible features a pilot sphere measuring 1.1 metres in diameter, the sphere, with steel walls 64 mm thick, was tested for its ability to withstand the required 114 megapascals of pressure in a pressure chamber at Pennsylvania State University. The sphere sits at the base of the 11. 8-tonne vehicle, the vehicle operates in a vertical attitude, and carries 500 kg of ballast weight that allows it to both sink to the bottom, and when released, rise to the surface. In late January 2012, to test systems, Cameron spent three hours in the submersible while submerged just below the surface in Australias Sydney Naval Yard. On 21 February 2012, a test dive intended to reach a depth of over 1,000 m was aborted after only an hour because of problems with cameras and life support systems. On 28 February 2012, during a dive, Cameron spent six hours in the submersible at a depth of 3,700 m. Power system fluctuations and unforeseen currents presented unexpected challenges, on 4 March 2012, a record-setting dive to more than 7,260 m stopped short of the bottom of the New Britain Trench when problems with the vertical thrusters led Cameron to return to the surface. Days later, with the problem solved, Cameron successfully took the submersible to the bottom of the New Britain Trench. There, he found a plain of loose sediment, anemones, jellyfish
32.
Ocean current
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Depth contours, shoreline configurations, and interactions with other currents influence a currents direction and strength. Therefore ocean currents are primarily horizontal water movements, Ocean currents flow for great distances, and together, create the global conveyor belt which plays a dominant role in determining the climate of many of the Earth’s regions. More specifically, ocean currents influence the temperature of the regions through which they travel, for example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any region at the same latitude. Another example is Lima, Peru where the climate is cooler than the tropical latitudes in which the area is located, in these wind driven currents, the Ekman spiral effect results in the currents flowing at an angle to the driving winds. In addition, the areas of ocean currents move somewhat with the seasons. Deep ocean basins generally have a surface current, in that the eastern equatorward-flowing branch is broad. These western boundary currents are a consequence of the rotation of the Earth, Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation is known as the oceans conveyor belt. These currents, called submarine rivers, flow under the surface of the ocean and are hidden from immediate detection, where significant vertical movement of ocean currents is observed, this is known as upwelling and downwelling. Deep ocean currents are currently being researched using a fleet of robots called Argo. The South Equatorial Currents of the Atlantic and Pacific straddle the equator, though the Coriolis effect is weak near the equator, water moving in the currents on either side of the equator is deflected slightly poleward and replaced by deeper water. Thus, equatorial upwelling occurs in these westward flowing equatorial surface currents, upwelling is an important process because this water from within and below the pycnocline is often rich in nutrients and greatly benefits the growth of marine organisms. By contrast, generally poor conditions for growth prevail in most of the tropical ocean because strong layering isolates deep. Ocean currents are measured in sverdrup, where 1 sv is equivalent to a flow rate of 1,000,000 m3 per second. Surface currents are found on the surface of an ocean, and are driven by large scale wind currents and they are directly affected by the wind—the Coriolis effect plays a role in their behaviors. Horizontal and vertical currents also exist below the pycnocline in the deeper waters. The movement of water due to differences in density as a function of water temperature, ripple marks in sediments, scour lines, and the erosion of rocky outcrops on deep-ocean floors are evidence that relatively strong, localized bottom currents exist
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Biological pump
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The biological pump, in its simplest form, is the oceans biologically driven sequestration of carbon from the atmosphere to deep sea water and sediment. The biological pump can be divided into three phases, the first of which is the production of fixed carbon by planktonic phototrophs in the euphotic surface region of the ocean. In these surface waters, phytoplankton use carbon dioxide, nitrogen, phosphorus, and other trace elements during photosynthesis to make carbohydrates, lipids, some plankton, combine calcium and dissolved carbonates to form a calcium carbonate protective coating. The sinking particles will often form aggregates as they sink, greatly increasing the sinking rate and it is this aggregation that gives particles a better chance of escaping predation and decomposition in the water column and eventually make it to the sea floor. The fixed carbon that is decomposed by bacteria on the way down or once on the sea floor then enters the final phase of the pump and is remineralized to be used again in primary production. The particles that escape these processes entirely are sequestered in the sediment and it is this sequestered carbon that is responsible for ultimately lowering atmospheric CO2. The first step in the pump is the synthesis of both organic and inorganic carbon compounds by phytoplankton in the uppermost, sunlit layers of the ocean. The ratio of carbon to nitrogen and phosphorus varies little and has a ratio of 106C, 16N, 1P. Oceanic primary production accounts for half of the carbon fixation carried out on Earth. Approximately 50–60 Pg of carbon are fixed by marine phytoplankton each year despite the fact that they comprise less than 1% of the total biomass on Earth. The majority of carbon fixation is carried out in the open ocean while the remaining amount occurs in the very productive upwelling regions of the ocean. Despite these productive regions producing 2 to 3 times as much fixed carbon per area, carbon is also biologically fixed in the form of calcium carbonate used as a protective coating for many planktonic species as well as larger marine organisms. The formation and sinking of CaCO3 drives a surface to deep alkalinity gradient which serves to raise the pressure of dissolved CO2 in surface waters. In addition, the sequestration of CaCO3 serves to lower overall oceanic alkalinity, the vast majority of carbon incorporated in organic and inorganic biological matter is formed at the sea surface and then must sink to the ocean floor. A single phytoplankton cell has a rate around 1 m per day and with 4000 m as the average depth of the ocean. However, through such as coagulation and expulsion in predator fecal pellets. These aggregates, known as snow, have sinking rates orders of magnitude greater than individual cells. Of the 50–60 Pg of carbon fixed annually, roughly 10% leaves the surface mixed layer of the oceans, most is retained in regenerated production in the euphotic zone and a significant portion is remineralized in midwater processes during particle sinking
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Dissolved organic carbon
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Dissolved organic carbon is a broad classification for organic molecules of varied origin and composition within aquatic systems. The dissolved fraction of carbon is an operational classification. Many researchers use the term dissolved for compounds below 0.45 micrometers, a practical definition of dissolved typically used in marine chemistry is all substances that pass through a GF/F filter. The recommended measure technique is the HTCO technique after filtration on precombusted glass fiber filters, the source of DOC depends on the body of water. In general, organic compounds are a result of decomposition processes from dead organic matter such as plants or marine organisms. When water contacts highly organic soils, these components can drain into rivers, DOC is also extremely important in the transport of metals in aquatic systems. Metals form extremely strong complexes with DOC, enhancing metal solubility while also reducing metal bioavailability, DOC is a food supplement, supporting growth of microorganisms and plays an important role in the global carbon cycle through the microbial loop. Moreover, it is an indicator of organic loadings in streams, dissolved organic carbon has a high proportion of biodegradable dissolved organic carbon in first order streams compared to higher order streams. In the absence of extensive wetlands, bogs, or swamps, Carbon concentrations considerably vary across ecosystems. For example, the Everglades may be near the top of the range, occasionally, high concentrations of organic carbon indicate anthropogenic influences, but most DOC originates naturally. The BDOC fraction consists of organic molecules that heterotrophic bacteria can use as a source of energy, some subset of DOC constitutes the precursors of disinfection byproducts for drinking water. BDOC can contribute to undesirable biological regrowth within water distribution systems, more precise measurement techniques developed in the late 1990s have allowed for a good understanding of how DOC is distributed in marine environments both vertically and across the surface. It is now understood that DOC in the ocean spans a range from very labile to very refractory. The labile DOC is mainly produced by organisms and is consumed in the surface ocean, and consists of sugars, proteins. Therefore, the vertical distribution consists of high concentrations in the upper water column. In addition to vertical distributions, horizontal distributions have been modeled and sampled as well, in the surface ocean at a depth of 30 meters, the higher DOC concentrations are found in the South Pacific Gyre, the South Atlantic Gyre, and the Indian Ocean. At a depth of 3000 meters, highest concentrations are in the North Atlantic Deep Water where DOC from the high concentration surface ocean is removed to depth, colored dissolved organic matter Foam lines Microbial loop Stone, Richard. Marine Biogeochemistry, The Invisible Hand Behind A Vast Carbon Reservoir
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Marine snow
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In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the photic zone to the aphotic zone below. The term was first coined by the explorer William Beebe as he observed it from his bathysphere, as the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for living in the aphotic zone. Marine snow is made up of a variety of organic matter, including dead or dying animals and phytoplankton, protists, fecal matter, sand. A majority of marine snow composition is made up of aggregates of smaller particles held together by a sugary mucus. These are natural polymers exuded as waste products mostly by phytoplankton, mucus secreted by zooplankton also contribute to the constituents of marine snow aggregates. These aggregates grow over time and may reach several centimeters in diameter, Marine snow often forms during algal blooms. As phytoplankton accumulate, they aggregate or get captured in other aggregates, aggregation and sinking is actually thought to be a large component of sources for algae loss from surface water. Most organic components of marine snow are consumed by microbes, zooplankton, the small percentage of material not consumed in shallower waters becomes incorporated into the muddy ooze blanketing the ocean floor, where it is further decomposed through biological activity. Marine snow aggregates exhibit characteristics that fit Goldmans aggregate spinning wheel hypothesis and this hypothesis states that phytoplankton, microorganisms and bacteria live attached to aggregate surfaces and are involved in rapid nutrient recycling. Phytoplankton have been shown to be able to take up nutrients from small local concentrations of organic material, as the aggregates slowly sink to the bottom of the ocean, the many microorganisms residing on them are constantly respiring and contribute greatly to the microbial loop. Aggregates begin as the fraction, which typically contains particles sized between 1 nm and several micrometers. The colloidal fraction of the ocean contains an amount of organic matter unavailable to grazers. This fraction has a higher total mass than either phytoplankton or bacteria but is not readily available due to size characteristics of the particles in relation to potential consumers. The colloidal fraction must aggregate in order to be more bioavailable, Particles in Brownian motion interact randomly due to the impact of solute molecules. These interactions lead to collision and aggregation of small particles. The small aggregates then collide and aggregate with other aggregates and particles until the aggregate in question is several micrometers in diameter, shear Once particles have aggregated to several micrometers in diameter, they begin to accumulate bacteria, since there is sufficient site space for feeding and reproduction
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Benthos
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Benthos is the community of organisms that live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column. The pressure difference can be very significant and this dead and decaying matter sustains the benthic food chain, most organisms in the benthic zone are scavengers or detritivores. The term benthos, coined by Haeckel in 1891, comes from the Greek noun βένθος depth of the sea, Benthos is also used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams. There is also a redundant synonym, benthon, the main food sources for the benthos are algae and organic runoff from land. The depth of water, temperature and salinity, and type of local substrate all affect what benthos is present, in coastal waters and other places where light reaches the bottom, benthic photosynthesizing diatoms can proliferate. Filter feeders, such as sponges and bivalves, dominate hard, deposit feeders, such as polychaetes, populate softer bottoms. Fish, such as dragonets, as well as sea stars, snails, cephalopods, and crustaceans are important predators and scavengers. Benthic organisms, such as sea stars, oysters, clams, sea cucumbers, brittle stars and sea anemones, play an important role as a source for fish, such as the California sheephead. They are easily visible to the eye with the lower range of body size at 0.5 mm. In the coastal water ecosystem, they include several species of organisms from different taxa including Porifera, Annelids, Coelenterates, Mollusks, Crustaceans, zoobenthos comprises the animals belonging to the benthos. Phytobenthos comprises the plants belonging to the benthos, mainly benthic diatoms, endobenthos lives buried, or burrowing in the sediment, often in the oxygenated top layer, e. g. a sea pen or a sand dollar. Epibenthos lives on top of the sediments, e. g. like a sea cucumber or a sea snail crawling about, hyperbenthos lives just above the sediment, e. g. a rock cod. Contrast the terms plankton, nekton, and neuston, ryan, Paddy Benthic communities Te Ara - the Encyclopædia of New Zealand, updated 21 September 2007. Yip, Maricela and Madl, Pierre Benthos University of Salzburg
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Mid-ocean ridges
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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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Primary production
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In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. Almost all life on Earth relies directly or indirectly on primary production, the organisms responsible for primary production are known as primary producers or autotrophs, and form the base of the food chain. In terrestrial ecoregions, these are mainly plants, while in aquatic ecoregions algae predominate in this role, ecologists distinguish primary production as either net or gross, the former accounting for losses to processes such as cellular respiration, the latter not. Primary production is the production of energy in organic compounds by living organisms. The main source of energy is sunlight but a minute fraction of primary production is driven by lithotrophic organisms using the chemical energy of inorganic molecules. Regardless of its source, this energy is used to complex organic molecules from simpler inorganic compounds such as carbon dioxide. Consumption of primary producers by heterotrophic organisms, such as animals, then transfers these organic molecules up the food web, gross primary production is the amount of chemical energy as biomass that primary producers create in a given length of time. Some fraction of this energy is used by primary producers for cellular respiration. The remaining fixed energy is referred to as net primary production, some net primary production goes toward growth and reproduction of primary producers, while some is consumed by herbivores. Both gross and net primary production are in units of mass per area per unit time interval. In terrestrial ecosystems, mass of carbon per area per year is most often used as the unit of measurement. On the land, almost all production is now performed by vascular plants, with a small fraction coming from algae and non-vascular plants such as mosses. Before the evolution of plants, non-vascular plants likely played a more significant role. Primary production on land is a function of many factors, but principally local hydrology, while plants cover much of the Earths surface, they are strongly curtailed wherever temperatures are too extreme or where necessary plant resources are limiting, such as deserts or polar regions. Water is consumed in plants by the processes of photosynthesis and transpiration, the latter process is driven by the evaporation of water from the leaves of plants. Transpiration allows plants to transport water and mineral nutrients from the soil to growth regions, diffusion of water vapour out of a leaf, the force that drives transpiration, is regulated by structures known as stomata. These structure also regulate the diffusion of carbon dioxide from the atmosphere into the leaf, certain plants use alternative forms of photosynthesis, called Crassulacean acid metabolism and C4. In a reversal of the pattern on land, in the oceans, almost all photosynthesis is performed by algae, with a small fraction contributed by vascular plants, algae encompass a diverse range of organisms, ranging from single floating cells to attached seaweeds
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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
