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82-524: Vema Seamount is a seamount in the South Atlantic Ocean . Discovered in 1959 by a ship with the same name, it lies 1,600 kilometres (1,000 mi) from Tristan da Cunha and 1,000 kilometres (620 mi) northwest of Cape Town . The seamount has a flat top at a mean depth of 73 metres (40 fathoms ) which was eroded into the seamount at a time when sea levels were lower; the shallowest point lies at 26 metres (14 fathoms) depth. The seamount

164-409: A buffer to stabilise it in the range 7.37–7.43: Exhaled CO 2 (g) depletes CO 2 (aq) , which in turn consumes H 2 CO 3 , causing the equilibrium of the first reaction to try to restore the level of carbonic acid by reacting bicarbonate with a hydrogen ion, an example of Le Châtelier's principle . The result is to make the blood more alkaline (raise pH). By the same principle, when

246-415: A commensal relationship , for example brittle stars , who climb the coral to get themselves off the seafloor, helping them to catch food particles, or small zooplankton, as they drift by. This is in sharp contrast with the typical deep-sea habitat, where deposit-feeding animals rely on food they get off the ground. In tropical zones extensive coral growth results in the formation of coral atolls late in

328-399: A certain pattern in terms of eruptive activity, first observed with Hawaiian seamounts but now shown to be the process followed by all seamounts of the ocean-ridge type. During the first stage the volcano erupts basalt of various types, caused by various degrees of mantle melting . In the second, most active stage of its life, ocean-ridge volcanoes erupt tholeiitic to mildly alkalic basalt as

410-720: A classic example being the Emperor Seamounts , an extension of the Hawaiian Islands . Formed millions of years ago by volcanism , they have since subsided far below sea level. This long chain of islands and seamounts extends thousands of kilometers northwest from the island of Hawaii . There are more seamounts in the Pacific Ocean than in the Atlantic, and their distribution can be described as comprising several elongate chains of seamounts superimposed on

492-437: A daunting task due to their sheer number. The most detailed seamount mappings are provided by multibeam echosounding ( sonar ), however after more than 5000 publicly held cruises, the amount of the sea floor that has been mapped remains minuscule. Satellite altimetry is a broader alternative, albeit not as detailed, with 13,000 catalogued seamounts; however this is still only a fraction of the total 100,000. The reason for this

574-500: A depth of 4,600 metres (2,500 fathoms), where it occupies a breadth of 56 kilometres (35 mi) and forms an isolated conical feature. The seafloor from which Vema rises is part of the abyssal plain of the Cape Basin . From there, the slopes of Vema first rise steeply and feature subsidiary summits; above 130 metres (70 fathoms) depth the slopes flatten. Volcanic rocks such as tuff as well as calcareous aggregates are found on

656-405: A global understanding of seamount ecosystems, and the roles they have in the biogeography , biodiversity , productivity and evolution of marine organisms. Possibly the best ecologically studied seamount in the world is Davidson Seamount , with six major expeditions recording over 60,000 species observations. The contrast between the seamount and the surrounding area was well-marked. One of

738-471: A minimum depth of 11 metres (36 ft) for the seamount, while recent bathymetric surveys have found a minimum depth of 21.5 metres (71 ft). The flat top is a summit plateau with a width of 8.0 kilometres (5 mi) and as more recently determined 11 by 8.5 kilometres (6.8 mi × 5.3 mi) at a mean depth of 73 metres (40 fathoms) and has been named Emerson Plateau; it has a vaguely triangular shape pointing west, and Collins Point lies close to

820-587: A model with fractional bonds and delocalized charges: Metal carbonates generally decompose on heating, liberating carbon dioxide leaving behind an oxide of the metal. This process is called calcination , after calx , the Latin name of quicklime or calcium oxide , CaO, which is obtained by roasting limestone in a lime kiln : As illustrated by its affinity for Ca , carbonate is a ligand for many metal cations. Transition metal carbonate and bicarbonate complexes feature metal ions covalently bonded to carbonate in

902-651: A more or less random background distribution. Seamount chains occur in all three major ocean basins, with the Pacific having the most number and most extensive seamount chains. These include the Hawaiian (Emperor), Mariana, Gilbert, Tuomotu and Austral Seamounts (and island groups) in the north Pacific and the Louisville and Sala y Gomez ridges in the southern Pacific Ocean. In the North Atlantic Ocean,

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984-468: A number of seamounts are active undersea volcanoes; two examples are Kamaʻehuakanaloa (formerly Lo‘ihi) in the Hawaiian Islands and Vailulu'u in the Manu'a Group ( Samoa ). The most apparent lava flows at a seamount are the eruptive flows that cover their flanks, however igneous intrusions , in the forms of dikes and sills , are also an important part of seamount growth. The most common type of flow

1066-420: A particular pattern of growth, activity, subsidence and eventual extinction. The first stage of a seamount's evolution is its early activity, building its flanks and core up from the sea floor. This is followed by a period of intense volcanism, during which the new volcano erupts almost all (e.g. 98%) of its total magmatic volume. The seamount may even grow above sea level to become an oceanic island (for example,

1148-429: A result of a larger area melting in the mantle. This is finally capped by alkalic flows late in its eruptive history, as the link between the seamount and its source of volcanism is cut by crustal movement. Some seamounts also experience a brief "rejuvenated" period after a hiatus of 1.5 to 10 million years, the flows of which are highly alkalic and produce many xenoliths . In recent years, geologists have confirmed that

1230-466: A sample from 3,000 metres (9,800 ft) depth gave an age of 18 million years. Light-coloured rocks on the summit platform may constitute a former carbonate platform. Vema is an intraplate volcano. It is considered to be the present-day location of a hotspot , the Vema hotspot, although the hotspot itself may have moved farther south or west (by about 200 kilometres (120 mi)) since when it created

1312-460: A summit collapse on the northern edge of Vlinder Seamount resulted in a pronounced headwall scarp and a field of debris up to 6 km (4 mi) away. A catastrophic collapse at Detroit Seamount flattened its whole structure extensively. Lastly, in 2004, scientists found marine fossils 61 m (200 ft) up the flank of Kohala mountain in Hawaii . Subsidation analysis found that at

1394-484: A total area of 8,796,150 km (3,396,210 sq mi), have been mapped but only a few have been studied in detail by scientists. Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Kamaʻehuakanaloa (formerly Lōʻihi) in

1476-406: A variety of bonding modes. Lithium , sodium , potassium , rubidium , caesium , and ammonium carbonates are water-soluble salts, but carbonates of 2+ and 3+ ions are often poorly soluble in water. Of the insoluble metal carbonates, CaCO 3 is important because, in the form of scale , it accumulates in and impedes flow through pipes. Hard water is rich in this material, giving rise to

1558-484: A wide variety of tectonic settings, resulting in a very diverse structural bank. Seamounts come in a wide variety of structural shapes, from conical to flat-topped to complexly shaped. Some are built very large and very low, such as Koko Guyot and Detroit Seamount ; others are built more steeply, such as Kamaʻehuakanaloa Seamount and Bowie Seamount . Some seamounts also have a carbonate or sediment cap . Many seamounts show signs of intrusive activity , which

1640-425: Is Bowie Seamount , which has also been declared a marine protected area by Canada for its ecological richness. The study of seamounts has been hindered for a long time by the lack of technology. Although seamounts have been sampled as far back as the 19th century, their depth and position meant that the technology to explore and sample seamounts in sufficient detail did not exist until the last few decades. Even with

1722-413: Is pillow lava , named so after its distinctive shape. Less common are sheet flows, which are glassy and marginal, and indicative of larger-scale flows. Volcaniclastic sedimentary rocks dominate shallow-water seamounts. They are the products of the explosive activity of seamounts that are near the water's surface, and can also form from mechanical wear of existing volcanic rock. Seamounts can form in

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1804-532: Is a salt of carbonic acid , ( H 2 CO 3 ), characterized by the presence of the carbonate ion , a polyatomic ion with the formula CO 2− 3 . The word "carbonate" may also refer to a carbonate ester , an organic compound containing the carbonate group O=C(−O−) 2 . The term is also used as a verb, to describe carbonation : the process of raising the concentrations of carbonate and bicarbonate ions in water to produce carbonated water and other carbonated beverages – either by

1886-402: Is double bonded. These compounds are also known as organocarbonates or carbonate esters, and have the general formula R−O−C(=O)−O−R′ , or RR′CO 3 . Important organocarbonates include dimethyl carbonate , the cyclic compounds ethylene carbonate and propylene carbonate , and the phosgene replacement, triphosgene . Three reversible reactions control the pH balance of blood and act as

1968-490: Is helped by geochemical exchange between the seamounts and the ocean water. Seamounts may thus be vital stopping points for some migratory animals , specifically whales . Some recent research indicates whales may use such features as navigational aids throughout their migration. For a long time it has been surmised that many pelagic animals visit seamounts as well, to gather food, but proof of this aggregating effect has been lacking. The first demonstration of this conjecture

2050-406: Is hurt by the simple lack of information available. Seamounts are very poorly studied, with only 350 of the estimated 100,000 seamounts in the world having received sampling, and fewer than 100 in depth. Much of this lack of information can be attributed to a lack of technology, and to the daunting task of reaching these underwater structures; the technology to fully explore them has only been around

2132-604: Is likely to lead to inflation , steepening of volcanic slopes, and ultimately, flank collapse. There are also several sub-classes of seamounts. The first are guyots , seamounts with a flat top. These tops must be 200 m (656 ft) or more below the surface of the sea; the diameters of these flat summits can be over 10 km (6.2 mi). Knolls are isolated elevation spikes measuring less than 1,000 meters (3,281 ft). Lastly, pinnacles are small pillar-like seamounts. Seamounts are exceptionally important to their biome ecologically, but their role in their environment

2214-721: Is one of the first instances of a seamount fishery collapsing, and has been cited as an example of how fisheries outside of exclusive economic zones end up ungoverned and abused. Vema Seamount was closed to fishery in 2007 by the South East Atlantic Fisheries Organisation , and man-made debris such as crab traps and ropes can be found there. The ecosystem is classified as "threatened" by the Food and Agriculture Organization . Seamount Earth's oceans contain more than 14,500 identified seamounts, of which 9,951 seamounts and 283 guyots, covering

2296-452: Is poorly understood. Because they project out above the surrounding sea floor, they disturb standard water flow, causing eddies and associated hydrological phenomena that ultimately result in water movement in an otherwise still ocean bottom. Currents have been measured at up to 0.9 knots, or 48 centimeters per second. Because of this upwelling seamounts often carry above-average plankton populations, seamounts are thus centers where

2378-441: Is related to the disparate lattice energies of solids composed of mono- vs dianions, as well as mono- vs dications. In aqueous solution , carbonate, bicarbonate, carbon dioxide, and carbonic acid participate in a dynamic equilibrium . In strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion is prevalent. In more acid conditions, aqueous carbon dioxide , CO 2 (aq) ,

2460-477: Is responsible for as much as 95% of ecological damage to seamounts. Corals from seamounts are also vulnerable, as they are highly valued for making jewellery and decorative objects. Significant harvests have been produced from seamounts, often leaving coral beds depleted. Individual nations are beginning to note the effect of fishing on seamounts, and the European Commission has agreed to fund

2542-404: Is that often, in the late of stages of their life, extrusions begin to seep in the seamount. This activity leads to inflation, over-extension of the volcano's flanks, and ultimately flank collapse , leading to submarine landslides with the potential to start major tsunamis , which can be among the largest natural disasters in the world. In an illustration of the potent power of flank collapses,

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2624-399: Is that the fishes that are targeted over seamounts are typically long-lived, slow-growing, and slow-maturing. The problem is confounded by the dangers of trawling , which damages seamount surface communities, and the fact that many seamounts are located in international waters, making proper monitoring difficult. Bottom trawling in particular is extremely devastating to seamount ecology, and

2706-463: Is that uncertainties in the technology limit recognition to features 1,500 m (4,921 ft) or larger. In the future, technological advances could allow for a larger and more detailed catalogue. Observations from CryoSat-2 combined with data from other satellites has shown thousands of previously uncharted seamounts, with more to come as data is interpreted. Seamounts are a possible future source of economically important metals. Even though

2788-439: Is the type locality for the deepwater sponge Desmacidon clavata . A number of fish have been encountered at Vema, although most fish species appear to be pelagic species that are not directly bound to the seamount environment. Fishing operations have attracted seabirds to Vema Seamount. Humpback whales have been detected through their sounds, and baleen whales feed at Vema. Euphausiids and copepods are also found in

2870-444: Is the main form, which, with water, H 2 O , is in equilibrium with carbonic acid – the equilibrium lies strongly towards carbon dioxide. Thus sodium carbonate is basic, sodium bicarbonate is weakly basic, while carbon dioxide itself is a weak acid. In organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which

2952-453: Is the simplest oxocarbon anion . It consists of one carbon atom surrounded by three oxygen atoms, in a trigonal planar arrangement, with D 3h molecular symmetry . It has a molecular mass of 60.01  g/mol and carries a total formal charge of −2. It is the conjugate base of the hydrogencarbonate (bicarbonate) ion, HCO − 3 , which is the conjugate base of H 2 CO 3 , carbonic acid . The Lewis structure of

3034-498: The 2009 eruption of Hunga Tonga ). After a period of explosive activity near the ocean surface , the eruptions slowly die away. With eruptions becoming infrequent and the seamount losing its ability to maintain itself, the volcano starts to erode . After finally becoming extinct (possibly after a brief rejuvenated period), they are ground back down by the waves. Seamounts are built in a far more dynamic oceanic setting than their land counterparts, resulting in horizontal subsidence as

3116-451: The Hawaiian Islands . Because of their abundance, seamounts are one of the most common marine ecosystems in the world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton , corals , fish, and marine mammals alike. Their aggregational effect has been noted by the commercial fishing industry , and many seamounts support extensive fisheries. There are ongoing concerns on

3198-761: The New England Seamounts extend from the eastern coast of the United States to the mid-ocean ridge. Craig and Sandwell noted that clusters of larger Atlantic seamounts tend to be associated with other evidence of hotspot activity, such as on the Walvis Ridge , Vitória-Trindade Ridge , Bermuda Islands and Cape Verde Islands . The mid-Atlantic ridge and spreading ridges in the Indian Ocean are also associated with abundant seamounts. Otherwise, seamounts tend not to form distinctive chains in

3280-437: The sea snail species Austromitra rosenbergi discovered in 2015 and the sponge Strongylodesma areolata described in 1969; it is estimated that about 22-36% of all species at Vema are endemic, similar to the proportion of endemic species at other seamounts of the world. The holothurian Holothuria vemae is named after the seamount, where it was discovered in 1965-1966 as is the sea snail Trivia vemacola . Vema Seamount

3362-479: The Indian and Southern Oceans, but rather their distribution appears to be more or less random. Isolated seamounts and those without clear volcanic origins are less common; examples include Bollons Seamount , Eratosthenes Seamount , Axial Seamount and Gorringe Ridge . If all known seamounts were collected into one area, they would make a landform the size of Europe . Their overall abundance makes them one of

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3444-524: The OASIS project, a detailed study of the effects of fishing on seamount communities in the North Atlantic . Another project working towards conservation is CenSeam , a Census of Marine Life project formed in 2005. CenSeam is intended to provide the framework needed to prioritise, integrate, expand and facilitate seamount research efforts in order to significantly reduce the unknown and build towards

3526-538: The Vema Seamount and may not be active anymore. Earlier volcanism caused by the Vema hotspot may have manifested itself in southern Namibia in the form of alkaline volcanics that define a HIMU suite. Seismic tomography has shown what may be a mantle plume underneath Vema, another theory considers the Vema hotspot is a consequence of the Tristan hotspot shedding a secondary diapir . The hotspot origin of

3608-488: The Vema Seamount is not universally agreed upon. Water temperatures at Vema range between 18–21 °C (64–70 °F), and decrease with increasing depth. The cold Benguela Current does not reach the seamount, which is instead influenced by the South Atlantic oceanic gyre . The movement and strength of ocean eddies are altered when they interact with Vema Seamount, with Agulhas eddies often splitting apart at

3690-512: The addition of carbon dioxide gas under pressure or by dissolving carbonate or bicarbonate salts into the water. In geology and mineralogy , the term "carbonate" can refer both to carbonate minerals and carbonate rock (which is made of chiefly carbonate minerals), and both are dominated by the carbonate ion, CO 2− 3 . Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock . The most common are calcite or calcium carbonate , CaCO 3 ,

3772-695: The average size of seamounts. Nearly 50% of guyot area and 42% of the number of guyots occur in the North Pacific Ocean, covering 342,070 km (132,070 sq mi). The largest three guyots are all in the North Pacific: the Kuko Guyot (estimated 24,600 km (9,500 sq mi)), Suiko Guyot (estimated 20,220 km (7,810 sq mi)) and the Pallada Guyot (estimated 13,680 km (5,280 sq mi)). Seamounts are often found in groupings or submerged archipelagos ,

3854-459: The carbonate ion has two (long) single bonds to negative oxygen atoms, and one short double bond to a neutral oxygen atom. This structure is incompatible with the observed symmetry of the ion, which implies that the three bonds are the same length and that the three oxygen atoms are equivalent. As in the case of the isoelectronic nitrate ion, the symmetry can be achieved by a resonance among three structures: This resonance can be summarized by

3936-453: The chief constituent of limestone (as well as the main component of mollusc shells and coral skeletons); dolomite , a calcium-magnesium carbonate CaMg(CO 3 ) 2 ; and siderite , or iron(II) carbonate , FeCO 3 , an important iron ore . Sodium carbonate ("soda" or "natron"), Na 2 CO 3 , and potassium carbonate ("potash"), K 2 CO 3 , have been used since antiquity for cleaning and preservation, as well as for

4018-750: The crust to the surface. Volcanoes formed near or above subducting zones are created because the subducting tectonic plate adds volatiles to the overriding plate that lowers its melting point . Which of these two process involved in the formation of a seamount has a profound effect on its eruptive materials. Lava flows from mid-ocean ridge and plate boundary seamounts are mostly basaltic (both tholeiitic and alkalic ), whereas flows from subducting ridge volcanoes are mostly calc-alkaline lavas. Compared to mid-ocean ridge seamounts, subduction zone seamounts generally have more sodium , alkali , and volatile abundances, and less magnesium , resulting in more explosive, viscous eruptions. All volcanic seamounts follow

4100-495: The distance from Cape Town is about 1,000 kilometres (620 mi). An unrelated seamount with the same name lies in the North Atlantic , close to the Mid-Atlantic Ridge . The seamount has a conical shape with a flat top; the shallowest point rises to an elevation of 26 metres (14 fathoms ) below sea level - later determined to be 21.5 metres (71 ft) deep - and is called Collins Point. At least one source gives

4182-425: The effect of seamounts on endemicity. They have , however, been confidently shown to provide a habitat to species that have difficulty surviving elsewhere. The volcanic rocks on the slopes of seamounts are heavily populated by suspension feeders , particularly corals , which capitalize on the strong currents around the seamount to supply them with food. These coral are therefore host to numerous other organisms in

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4264-465: The first two have any potential of being targeted by mining in the next few decades. Some seamounts have not been mapped and thus pose a navigational danger. For instance, Muirfield Seamount is named after the ship that hit it in 1973. More recently, the submarine USS San Francisco ran into an uncharted seamount in 2005 at a speed of 35 knots (40.3 mph; 64.8 km/h), sustaining serious damage and killing one seaman. One major seamount risk

4346-417: The fish that feed on them aggregate, in turn falling prey to further predation, making seamounts important biological hotspots. Seamounts provide habitats and spawning grounds for these larger animals, including numerous fish. Some species, including black oreo (Allocyttus niger) and blackstripe cardinalfish (Apogon nigrofasciatus) , have been shown to occur more often on seamounts than anywhere else on

4428-453: The gap. There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield Seamount is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses; as they get older, extrusions seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive tsunamis . Seamounts can be found in every ocean basin in

4510-497: The last few decades. Before consistent conservation efforts can begin, the seamounts of the world must first be mapped , a task that is still in progress. Overfishing is a serious threat to seamount ecological welfare. There are several well-documented cases of fishery exploitation, for example the orange roughy ( Hoplostethus atlanticus ) off the coasts of Australia and New Zealand and the pelagic armorhead ( Pseudopentaceros richardsoni ) near Japan and Russia. The reason for this

4592-473: The long-term carbon cycle, due to the large number of marine organisms (especially coral) which are made of calcium carbonate. Increased solubility of carbonate through increased temperatures results in lower production of marine calcite and increased concentration of atmospheric carbon dioxide. This, in turn, increases Earth temperature. The amount of CO 2− 3 available is on a geological scale and substantial quantities may eventually be redissolved into

4674-435: The manufacture of glass . Carbonates are widely used in industry, such as in iron smelting, as a raw material for Portland cement and lime manufacture, in the composition of ceramic glazes , and more. New applications of alkali metal carbonates include: thermal energy storage, catalysis and electrolyte both in fuel cell technology as well as in electrosynthesis of H 2 O 2 in aqueous media. The carbonate ion

4756-530: The most common, and least understood, marine structures and biomes on Earth, a sort of exploratory frontier. Most seamounts are built by one of two volcanic processes, although some, such as the Christmas Island Seamount Province near Australia, are more enigmatic. Volcanoes near plate boundaries and mid-ocean ridges are built by decompression melting of rock in the upper mantle . The lower density magma rises through

4838-412: The need for infrastructural water softening . Acidification of carbonates generally liberates carbon dioxide : Thus, scale can be removed with acid. In solution the equilibrium between carbonate, bicarbonate, carbon dioxide and carbonic acid is sensitive to pH, temperature, and pressure. Although di- and trivalent carbonates have low solubility, bicarbonate salts are far more soluble. This difference

4920-439: The negative impact of fishing on seamount ecosystems, and well-documented cases of stock decline, for example with the orange roughy ( Hoplostethus atlanticus ). 95% of ecological damage is done by bottom trawling , which scrapes whole ecosystems off seamounts. Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close

5002-470: The ocean floor. Marine mammals , sharks , tuna , and cephalopods all congregate over seamounts to feed, as well as some species of seabirds when the features are particularly shallow. Seamounts often project upwards into shallower zones more hospitable to sea life, providing habitats for marine species that are not found on or around the surrounding deeper ocean bottom. Because seamounts are isolated from each other they form "undersea islands" creating

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5084-470: The ocean makes up 70% of Earth's surface area, technological challenges have severely limited the extent of deep sea mining . But with the constantly decreasing supply on land, some mining specialists see oceanic mining as the destined future, and seamounts stand out as candidates. Seamounts are abundant, and all have metal resource potential because of various enrichment processes during the seamount's life. An example for epithermal gold mineralization on

5166-410: The pH is too high, the kidneys excrete bicarbonate ( HCO − 3 ) into urine as urea via the urea cycle (or Krebs–Henseleit ornithine cycle). By removing the bicarbonate, more H is generated from carbonic acid ( H 2 CO 3 ), which comes from CO 2 (g) produced by cellular respiration . Crucially, a similar buffer operates in the oceans. It is a major factor in climate change and

5248-406: The plateau. Collins Point is composed of phonolite , which contains aegirine , alkali feldspar , augite and nepheline . Olivine -containing basalt has also been found. A minimum age of 11.0 ± 0.3 million years has been obtained from samples taken at Collins Point by potassium-argon dating , with another age estimate being 15 million years. Older ages have been obtained deeper on the seamount;

5330-551: The primary ecological havens on the seamount is its deep sea coral garden, and many of the specimens noted were over a century old. Following the expansion of knowledge on the seamount there was extensive support to make it a marine sanctuary , a motion that was granted in 2008 as part of the Monterey Bay National Marine Sanctuary . Much of what is known about seamounts ecologically is based on observations from Davidson. Another such seamount

5412-399: The right technology available, only a scant 1% of the total number have been explored, and sampling and information remains biased towards the top 500 m (1,640 ft). New species are observed or collected and valuable information is obtained on almost every submersible dive at seamounts. Before seamounts and their oceanographic impact can be fully understood, they must be mapped,

5494-439: The same biogeographical interest. As they are formed from volcanic rock , the substrate is much harder than the surrounding sedimentary deep sea floor. This causes a different type of fauna to exist than on the seafloor, and leads to a theoretically higher degree of endemism . However, recent research especially centered at Davidson Seamount suggests that seamounts may not be especially endemic, and discussions are ongoing on

5576-412: The sea and released to the atmosphere, increasing CO 2 levels even more. It is generally thought that the presence of carbonates in rock is strong evidence for the presence of liquid water. Recent observations of the planetary nebula NGC 6302 show evidence for carbonates in space, where aqueous alteration similar to that on Earth is unlikely. Other minerals have been proposed which would fit

5658-728: The seafloor is Conical Seamount, located about 8 km south of Lihir Island in Papua New Guinea. Conical Seamount has a basal diameter of about 2.8 km and rises about 600 m above the seafloor to a water depth of 1050 m. Grab samples from its summit contain the highest gold concentrations yet reported from the modern seafloor (max. 230 g/t Au, avg. 26 g/t, n=40). Iron - manganese , hydrothermal iron oxide , sulfide , sulfate , sulfur , hydrothermal manganese oxide , and phosphorite (the latter especially in parts of Micronesia) are all mineral resources that are deposited upon or within seamounts. However, only

5740-475: The seamount moves with the tectonic plate towards a subduction zone . Here it is subducted under the plate margin and ultimately destroyed, but it may leave evidence of its passage by carving an indentation into the opposing wall of the subduction trench. The majority of seamounts have already completed their eruptive cycle, so access to early flows by researchers is limited by late volcanic activity. Ocean-ridge volcanoes in particular have been observed to follow

5822-529: The seamount's life. In addition soft sediments tend to accumulate on seamounts, which are typically populated by polychaetes ( annelid marine worms ) oligochaetes ( microdrile worms), and gastropod mollusks ( sea slugs ). Xenophyophores have also been found. They tend to gather small particulates and thus form beds, which alters sediment deposition and creates a habitat for smaller animals. Many seamounts also have hydrothermal vent communities, for example Suiyo and Kamaʻehuakanaloa seamounts. This

5904-401: The seamount. During the ice ages , sea level drop may have exposed part of the summit platform. The seamount features both shallow-water and deep-water life. Its summit is shallow enough that sunlight can reach it, resulting in the growth of various types of algae and seaweeds such as Ecklonia kelp . Such kelp covers large parts of the seamount, and a coral framework makes up much of

5986-704: The smallest seamounts found in the Arctic Ocean and the Mediterranean and Black Seas; whilst the largest mean seamount size, 890 km (340 sq mi), occurs in the Indian Ocean . The largest seamount has an area of 15,500 km (6,000 sq mi) and it occurs in the North Pacific. Guyots cover a total area of 707,600 km (273,200 sq mi) and have an average area of 2,500 km (970 sq mi), more than twice

6068-728: The summit platform. A number of animals inhabit Vema, usually hidden or encrusting animals. Ascidians , black corals , non- reef building corals including gorgonia and scleractinia , crayfish such as the rock lobster ( Jasus tristani ), and other decapods , holothurians , hydroids , polyzoa , sea fans and sponges live on the seamount. Other animals such as bryozoans , echinoderms , gastropods , oysters , pelecypods , serpulids and other worms have also left their traces on Vema. Rock lobsters propagate from Gough Island and Tristan da Cunha to Vema Seamount, while other species appear to originate from South Africa . Several species appear to be endemic to Vema Seamount, including

6150-441: The time of their deposition, this would have been 500 m (1,640 ft) up the flank of the volcano, far too high for a normal wave to reach. The date corresponded with a massive flank collapse at the nearby Mauna Loa , and it was theorized that it was a massive tsunami, generated by the landslide, that deposited the fossils. Geology Ecology Geography and geology Ecology Carbonate A carbonate

6232-403: The waters, including at least one copepod that parasitizes fish. Among the fish species encountered at Vema Seamount are: Fish on the seamount were commercially fished. Rock lobsters in particular were heavily exploited; they disappeared from Vema Seamount after overfishing in the 1960s, briefly recovered and then disappeared again by 1981 due to renewed overfishing. The collapse of this fishery

6314-531: The western margin of the Emerson Plateau. Other points on the Plateau also rise to depths of less than 55 metres (30 fathoms). The summit plateau mostly consists of hard rock, like the upper slopes, with rocky outcrops separated by sandy plains. The plateau appears to be a wave-cut platform of Pleistocene age, when sea levels were lower, and is swept by strong ocean currents . The seamount rises from

6396-702: The world's oceans. Most seamounts are volcanic in origin, and thus tend to be found on oceanic crust near mid-ocean ridges , mantle plumes , and island arcs . Overall, seamount and guyot coverage is greatest as a proportion of seafloor area in the North Pacific Ocean, equal to 4.39% of that ocean region. The Arctic Ocean has only 16 seamounts and no guyots, and the Mediterranean and Black seas together have only 23 seamounts and 2 guyots. The 9,951 seamounts which have been mapped cover an area of 8,088,550 km (3,123,010 sq mi). Seamounts have an average area of 790 km (310 sq mi), with

6478-415: The world, distributed extremely widely both in space and in age. A seamount is technically defined as an isolated rise in elevation of 1,000 m (3,281 ft) or more from the surrounding seafloor, and with a limited summit area, of conical form. There are more than 14,500 seamounts. In addition to seamounts, there are more than 80,000 small knolls , ridges and hills less than 1,000 m in height in

6560-644: Was discovered by the research ship RV  Vema of the Lamont–Doherty Earth Observatory in 1959. Vema was one of the first seamounts to be the subject of scientific study, and the first seamount investigated by scuba divers without special equipment. It lies in international waters and its summit is so shallow that it is a navigation hazard to ships. Vema Seamount lies in the South Atlantic Ocean , 1,600 kilometres (1,000 mi) from Tristan da Cunha . The cities of Cape Town and Lüderitz lie east-southeast and northeast of Vema, respectively;

6642-402: Was formed between 15-11 million years ago, possibly by a hotspot . The seamount rises high enough that its summit is at shallow depth, allowing sunlight to reach it and thus permitting the growth of kelp and algae . A number of sea animals and fish are encountered on the seamount; active fisheries existed at Vema Seamount and caused the disappearance of some animal species. Vema Seamount

6724-822: Was published in 2008. The effect that seamounts have on fish populations has not gone unnoticed by the commercial fishing industry . Seamounts were first extensively fished in the second half of the 20th century, due to poor management practices and increased fishing pressure seriously depleting stock numbers on the typical fishing ground, the continental shelf . Seamounts have been the site of targeted fishing since that time. Nearly 80 species of fish and shellfish are commercially harvested from seamounts, including spiny lobster (Palinuridae), mackerel (Scombridae and others), red king crab ( Paralithodes camtschaticus ), red snapper ( Lutjanus campechanus ), tuna (Scombridae), Orange roughy ( Hoplostethus atlanticus ), and perch (Percidae). The ecological conservation of seamounts

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