View source for Seamount

{{Short description|Mountain rising from the ocean seafloor that does not reach the water's surface}}
{{For|active seamounts|Submarine volcano}}
[[File:Bear Seamount.jpg|[[Bear Seamount]]|thumb]]
{{Ocean habitat topics}}

A '''seamount''' is a large submarine [[landform]] that rises from the [[seabed|ocean floor]] without reaching the water surface ([[sea level]]), and thus is not an [[island]], [[islet]], or [[cliff]]-rock. Seamounts are typically formed from [[volcano#Extinct|extinct volcano]]es that rise abruptly and are usually found rising from the seafloor to {{cvt|100|-|4000|m|ft}} in height. They are defined by [[oceanography|oceanographers]] as independent features that rise to at least {{cvt|1000|m|ft|0}} above the seafloor, characteristically of conical form.<ref name="IHO 2008">IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco.</ref> The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the [[deep sea]].<ref>Nybakken, James W. and Bertness, Mark D., 2008. ''Marine Biology: An Ecological Approach''. Sixth Edition. Benjamin Cummings, San Francisco</ref> During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface.  After they have subsided and sunk below the sea surface, such flat-top seamounts are called "[[guyot]]s" or "tablemounts".<ref name="IHO 2008"/>

Earth's oceans contain more than 14,500 identified seamounts,<ref name=Watts2019>{{cite journal |title=Science, Seamounts and Society |last=Watts|first=T. |journal=[[Geoscientist (magazine)|Geoscientist]] |date=August 2019 |pages=10–16}}</ref> of which 9,951 seamounts and 283 guyots, covering a total area of {{cvt|8,796,150|km2|sqmi}}, have been mapped<ref name="Harris, P.T. 2014">{{cite journal |last1=Harris|first1=P. T. |last2=MacMillan-Lawler|first2=M. |last3=Rupp|first3=J. |last4=Baker|first4=E. K. |year=2014 |title=Geomorphology of the oceans |journal=[[Marine Geology (journal)|Marine Geology]] |volume=352 |pages=4–24|doi=10.1016/j.margeo.2014.01.011 |bibcode=2014MGeol.352....4H }}</ref> 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 Seamount|Kamaʻehuakanaloa]] (formerly Lōʻihi) in the [[Hawaiian Islands]].

Because of their abundance, seamounts are one of the most common [[marine ecosystem]]s in the world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract [[plankton]], [[coral]]s, fish, and [[marine mammal]]s alike. Their aggregational effect has been noted by the [[commercial fishing|commercial fishing industry]], and many seamounts support extensive fisheries. There are ongoing concerns on 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 [[Altimeter#Satellites|satellite altimetry]] are two technologies working to close 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, [[extrusive rock|extrusions]] seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive [[tsunami]]s.

==Geography==
[[File:SeamontDavidson expedition bathymetric-2002.jpg|thumb|Bathymetric mapping of part of [[Davidson Seamount]]. The dots indicate significant coral nurseries.]]

Seamounts can be found in every [[ocean basin]] in the world, distributed extremely widely both in space and in age. A seamount is technically defined as an isolated rise in elevation of {{convert|1000|m|ft|0|abbr=on}} or more from the surrounding seafloor, and with a limited summit area,<ref name=EoE-seamount/> of conical form.<ref name="IHO 2008"/> There are more than 14,500 seamounts.<ref name=Watts2019/> In addition to seamounts, there are more than 80,000 small [[Hillock|knoll]]s, ridges and hills less than 1,000&nbsp;m in height in the world's oceans.<ref name="Harris, P.T. 2014"/>

Most seamounts are volcanic in origin, and thus tend to be found on [[oceanic crust]] near [[mid-ocean ridge]]s, [[mantle plume]]s, and [[island arc]]s. 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 Sea|Mediterranean]] and [[Black Sea|Black]] seas together have only 23 seamounts and 2 guyots. The 9,951 seamounts which have been mapped cover an area of {{convert|8088550|km2|abbr=on}}. Seamounts have an average area of {{convert|790|km2|abbr=on}}, with the smallest seamounts found in the Arctic Ocean and the Mediterranean and Black Seas; whilst the largest mean seamount size, {{convert|890|km2|abbr=on}}, occurs in the [[Indian Ocean]]. The largest seamount has an area of {{convert|15,500|km2|abbr=on}} and it occurs in the North Pacific. Guyots cover a total area of {{convert|707,600|km2|abbr=on}} and have an average area of {{convert|2,500|km2|abbr=on}}, more than twice the average size of seamounts. Nearly 50% of guyot area and 42% of the number of guyots occur in the North Pacific Ocean, covering {{convert|342,070|km2|abbr=on}}. The largest three guyots are all in the North Pacific: the Kuko Guyot (estimated {{convert|24,600|km2|abbr=on}}), [[Suiko Guyot]] (estimated {{convert|20,220|km2|abbr=on}}) and the [[Pallada Guyot]] (estimated {{convert|13,680|km2|abbr=on}}).<ref name="Harris, P.T. 2014"/>

===Grouping===
{{Redirect|Seamount chain|a broader coverage of this topic|Undersea mountain range}}
Seamounts are often found in groupings or submerged [[archipelago]]s, 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 [[Hawaii (island)|island of Hawaii]].

[[File:Distribution of seamounts and guyots in the North Pacific.pdf|thumb|Distribution of seamounts and guyots in the North Pacific]][[File:N Atlantic seamounts (Converted).pdf|thumb|Distribution of seamounts and guyots in the North Atlantic]]

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 a more or less random background distribution.<ref name="Craig, C.H. 1988">{{cite journal | last1 = Craig | first1 = C.H. | last2 = Sandwell | first2 = D.T. | year = 1988 | title = Global distribution of seamounts from Seasat profiles | journal = Journal of Geophysical Research | volume = 93 | issue = B9| pages = 10408–410, 420 | doi=10.1029/jb093ib09p10408 | bibcode=1988JGR....9310408C}}</ref>  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, the [[New England Seamounts]] extend from the eastern coast of the United States to the mid-ocean ridge. Craig and Sandwell<ref name="Craig, C.H. 1988"/> 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.<ref>Kitchingman, A., Lai, S., 2004. Inferences on Potential Seamount Locations from Mid-Resolution Bathymetric Data. in: Morato, T., Pauly, D. (Eds.), FCRR Seamounts: Biodiversity and Fisheries. Fisheries Centre Research Reports. University of British Columbia, Vancouver, BC, pages 7–12.</ref> Otherwise, seamounts tend not to form distinctive chains in the Indian and Southern Oceans, but rather their distribution appears to be more or less random.

Isolated seamounts and those without clear [[volcano|volcanic]] origins are less common; examples include [[Bollons Seamount]], [[Eratosthenes Seamount]], [[Axial Seamount]] and [[Gorringe Ridge]].<ref name=agu>{{cite book |doi=10.1029/GM043 |bibcode=1987GMS....43.....K |title=Seamounts, Islands, and Atolls |series=Geophysical Monograph Series |date=1987 |isbn=978-1-118-66420-9 |last1=Keating |first1=Barbara H. |last2=Fryer |first2=Patricia |last3=Batiza |first3=Rodey |last4=Boehlert |first4=George W. |volume=43 }}{{page needed|date=September 2024}}</ref>

If all known seamounts were collected into one area, they would make a landform the size of [[Europe]].<ref name=seasci>{{cite press release |title=Seamount scientists offer new comprehensive view of deep-sea mountains |url=https://www.sciencedaily.com/releases/2010/02/100222162013.htm |work=ScienceDaily |publisher=Scripps Institution of Oceanography / UC San Diego |date=23 February 2010 }}</ref> Their overall abundance makes them one of the most common, and least understood, marine structures and [[biome]]s on Earth,<ref name=seasci-sig /> a sort of exploratory frontier.<ref name=oceanography-geo />

==Geology==
===Geochemistry and evolution===
[[File:Submarine Eruption-numbers.svg|thumb|right|Diagram of a submarine eruption (key: 1. [[Water vapor|Water vapor cloud]] 2. Water  3. [[Stratum]] 4. [[Lava|Lava flow]] 5. [[Magma conduit]] 6. [[Magma chamber]] 7. [[Dike (geology)|Dike]] 8. [[Pillow lava]]) [[:File:Submarine Eruption-numbers.svg|Click to enlarge]]]]

Most seamounts are built by one of two volcanic processes, although some, such as the [[Christmas Island Seamount Province]] near Australia, are more enigmatic.<ref name=naturegeo>{{cite journal|author1=K. Hoernle |author2=F. Hauff |author3=R. Werner |author4=P. van den Bogaard |author5=A. D. Gibbons |author6=S. Conrad |author7=R. D. Müller |name-list-style=amp |title=Origin of Indian Ocean Seamount Province by shallow recycling of continental lithosphere|journal=[[Nature Geoscience]]|date=27 November 2011|volume=4|issue=12 |pages=883–887|doi=10.1038/ngeo1331|bibcode = 2011NatGe...4..883H |citeseerx=10.1.1.656.2778}}</ref> Volcanoes near [[Divergent boundary|plate boundaries]] and [[mid-ocean ridge]]s are built by [[Igneous rock#Decompression|decompression melting]] of rock in the [[upper mantle (Earth)|upper mantle]]. The lower density [[magma]] rises through the crust to the surface. Volcanoes formed near or above [[Subduction|subducting zones]] are created because the subducting [[tectonic plate]] adds [[Volatile (astrogeology)#Igneous petrology|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 [[basalt]]ic (both [[Tholeiitic basalt|tholeiitic]] and [[Igneous rock#Chemical classification|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.<ref name=oceanography-geo/>

All volcanic seamounts follow 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, the [[2009 Tonga undersea volcanic eruption|2009 eruption]] of [[Hunga Tonga]]). After a period of explosive activity near the [[sea level|ocean surface]], the eruptions slowly die away. With eruptions becoming infrequent and the seamount losing its ability to maintain itself, the volcano starts to [[Erosion#Water|erode]]. After finally becoming [[Volcano#Extinct|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 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.<ref name=oceanography-geo>{{cite journal|author1=Hubert Straudigal |author2=David A Clauge |name-list-style=amp |title=The Geological History of Deep-Sea Volcanoes: Biosphere, Hydrosphere, and Lithosphere Interactions |journal=[[Oceanography (journal)|Oceanography]] |volume=32 |series=Seamounts Special Issue |issue=1 |url=http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/23_1/23-1_staudigel2.pdf |access-date=25 July 2010 |archive-url=https://web.archive.org/web/20100613141518/http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/23_1/23-1_staudigel2.pdf |archive-date=13 June 2010}}</ref>

Ocean-ridge volcanoes in particular have been observed to follow a certain pattern in terms of eruptive activity, first observed with [[Hawaiian - Emperor seamount chain|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 (geology)#Movement|mantle melting]]. In the second, most active stage of its life, ocean-ridge volcanoes erupt tholeiitic to mildly alkalic basalt as 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 [[xenolith]]s.<ref name=oceanography-geo/>

In recent years, geologists have confirmed that a number of seamounts are active undersea volcanoes; two examples are [[Kamaʻehuakanaloa Seamount|Kamaʻehuakanaloa]] (formerly Lo'ihi) in the [[Hawaiian Islands]] and [[Vailulu'u]] in the [[Manua|Manu'a Group]] ([[Samoa]]).<ref name=agu/>

===Lava types===
[[File:Pillow basalt crop l.jpg|thumb|right|[[Pillow lava]], a type of [[basalt]] flow that originates from lava-water interactions during submarine eruptions<ref name="noaa-pillow lava">{{cite web|title=Pillow lava|url=http://www.pmel.noaa.gov/vents/nemo/explorer/concepts/pillows.html|publisher=[[NOAA]]|access-date=25 July 2010}}</ref>]]

The most apparent lava flows at a seamount are the eruptive flows that cover their flanks, however [[Intrusion (geology)|igneous intrusions]], in the forms of [[dike (geology)|dikes]] and [[Sill (geology)|sills]], are also an important part of seamount growth. The most common type of flow is [[pillow lava]], named so after its distinctive shape. Less common are sheet flows, which are [[Volcanic glass|glassy]] and marginal, and indicative of larger-scale flows. [[Pyroclastic rock|Volcaniclastic]] [[sedimentary rock|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.<ref name=oceanography-geo/>

===Structure===
Seamounts can form in 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.<ref name=oceanography-geo/> Some are built very large and very low, such as [[Koko Guyot]]<ref>{{cite web|url=http://www-odp.tamu.edu/publications/197_IR/chap_01/c1_9.htm|title=SITE 1206|work=Ocean Drilling Program Database-Results of Site 1206|publisher=[[Ocean Drilling Program]]|access-date=26 July 2010}}</ref> and [[Detroit Seamount]];<ref name="Stanford-2005">{{cite web|url=http://pangea.stanford.edu/research/groups/crustal/docs/Kerr.DetroitSeamount.G3.2005.pdf |title=Seismic stratigraphy of Detroit Seamount, Hawaiian–Emperor Seamount chain|author1=Kerr, B. C. |author2=D. W. Scholl |author3=S. L. Klemperer|date=July 12, 2005|publisher=[[Stanford University]]|access-date=15 July 2010}}</ref> others are built more steeply, such as [[Kamaʻehuakanaloa Seamount]]<ref name="HCV-Main">{{cite web| last = Rubin| first = Ken| title = General Information About Loihi| work = Hawaii Center for Volcanology| publisher = [[School of Ocean and Earth Science and Technology]]| date = January 19, 2006| url = http://www.soest.hawaii.edu/GG/HCV/loihi.html| access-date = 26 July 2010}}</ref> and [[Bowie Seamount]].<ref name=SI>{{cite web | title = The Bowie Seamount Area | publisher=John F. Dower and Frances J. Fee | date = February 1999 | url = http://www.dfo-mpo.gc.ca/Library/246468.pdf |access-date=26 July 2010}}</ref> Some seamounts also have a [[Carbonate rock|carbonate]] or [[sediment]] [[caprock|cap]].<ref name=oceanography-geo/>

Many seamounts show signs of [[intrusion|intrusive activity]], which is likely to lead to [[Deformation (volcanology)|inflation]], steepening of volcanic slopes, and ultimately, flank collapse.<ref name=oceanography-geo/> There are also several sub-classes of seamounts. The first are [[guyot]]s, seamounts with a flat top. These tops must be {{convert|200|m|ft|0|abbr=on}} or more below the surface of the sea; the diameters of these flat summits can be over {{convert|10|km|mi|1|abbr=on}}.<ref>{{cite encyclopedia|title=Guyots|url=http://www.britannica.com/EBchecked/topic/250080/guyot|encyclopedia=[[Encyclopædia Britannica]]|access-date=24 July 2010}}</ref>  [[Knoll (oceanography)|Knolls]] are isolated elevation spikes measuring less than {{convert|1000|m|ft|0|sp=us}}.{{clarify|date=July 2023}} Lastly, [[Pinnacle (geology)|pinnacles]] are small pillar-like seamounts.<ref name=EoE-seamount/>

{{clear}}

==Ecology==
===Ecological role of seamounts===
[[File:Diurnal Flow over a Ridge - NOAA-PMEL.gif|thumb|Animations depicting current flow over seamounts and ridges.]]

Seamounts are exceptionally important to their biome ecologically, but their role in their environment is poorly understood. Because they project out above the surrounding sea floor, they disturb standard water flow, causing [[Eddy (fluid dynamics)|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&nbsp;knots, or 48&nbsp;centimeters per second. Because of this upwelling seamounts often carry above-average [[plankton]] populations, seamounts are thus centers where the fish that feed on them aggregate, in turn falling prey to further predation, making seamounts important biological hotspots.<ref name=EoE-seamount>{{cite encyclopedia|title=Seamount|url=http://www.eoearth.org/article/Seamount|encyclopedia=[[Encyclopedia of Earth]]|access-date=24 July 2010|date=December 9, 2008}}</ref>

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 the ocean floor. [[Marine mammal]]s, [[shark]]s, [[tuna]], and [[cephalopod]]s all congregate over seamounts to feed, as well as some species of [[seabird]]s when the features are particularly shallow.<ref name=EoE-seamount/>

[[File:Bubblegum coral on davidson.jpg|thumb|right|[[Grenadier (fish)|Grenadier]] fish (''Coryphaenoides sp.'') and [[Bubblegum Coral|bubblegum coral]] (''Paragorgia arborea'') on the crest of [[Davidson Seamount]]. These are two species attracted to the seamount; ''Paragorgia arborea'' in particular grows in the surrounding area as well, but nowhere near as profusely.<ref name=physorg.com>{{cite web|url=http://www.physorg.com/news153594680.html|title=Seamounts may serve as refuges for deep-sea animals that struggle to survive elsewhere|publisher=[[PhysOrg]]|date=February 11, 2009|access-date=December 7, 2009}}</ref>]]

Seamounts often project upwards into shallower zones more hospitable to sea life, providing [[habitat (ecology)|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 the same [[biogeographical]] interest. As they are formed from [[volcanic rock]], the substrate is much harder than the surrounding [[sediment]]ary 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]].<ref name=noaa2006-sheet>{{cite web|url=http://oceanexplorer.noaa.gov/explorations/06davidson/background/conservation/davidson_fact_sheet.pdf|title=Davidson Seamount|year=2006|publisher=[[NOAA]], [[Monterey Bay National Marine Sanctuary]]|access-date=2 December 2009}}</ref> However, recent research especially centered at [[Davidson Seamount]] suggests that seamounts may not be especially endemic, and discussions are ongoing on the effect of seamounts on endemicity. They ''have'', however, been confidently shown to provide a habitat to species that have difficulty surviving elsewhere.<ref name="PLoS ONE-2009">{{cite journal|author2=Lundsten L. |author3=Ream M., Barry J. |author4=DeVogelaere A.|date=January 7, 2009|title=Endemicity, Biogeography, Composition, and Community Structure On a Northeast Pacific Seamount|journal=[[PLoS ONE]]|volume=4|issue=1|doi=10.1371/journal.pone.0004141|last=McClain|first=Craig R.|article-number=e4141|pmid=19127302|pmc=2613552|editor1-last=Rands|editor1-first=Sean|bibcode = 2009PLoSO...4.4141M |doi-access=free}}</ref><ref name="DeVogelaere et. al.-2009">{{cite journal|author2=J. P. Barry |author3=G. M. Cailliet |author4=D. A. Clague |author5=A. DeVogelaere |author6=J. B. Geller|date=January 13, 2009|title=Benthic invertebrate communities on three seamounts off southern and central California|journal=[[Marine Ecology Progress Series]]|volume=374|pages=23–32|doi=10.3354/meps07745|last=Lundsten|first=L|bibcode=2009MEPS..374...23L|doi-access=free}}</ref>

The volcanic rocks on the slopes of seamounts are heavily populated by [[suspension feeder]]s, particularly [[coral]]s, which capitalize on the strong currents around the seamount to supply them with food. These coral are therefore host to numerous other organisms in a [[commensal relationship]], for example [[brittle star]]s, who climb the coral to get themselves off the seafloor, helping them to catch food particles, or small zooplankton, as they drift by.<ref>{{cite web | url=https://oceanexplorer.noaa.gov/explorations/04mountains/background/commensals/commensals.html | title=NOAA Ocean Explorer: Mountains in the Sea 2004 }}</ref> This is in sharp contrast with the typical deep-sea habitat, where deposit-feeding animals rely on food they get off the ground.<ref name=EoE-seamount/> In [[tropical zone]]s extensive coral growth results in the formation of [[atoll|coral atoll]]s late in the seamount's life.<ref name="DeVogelaere et. al.-2009" /><ref name=oceanography-census />

In addition soft sediments tend to accumulate on seamounts, which are typically populated by [[polychaete]]s ([[annelid]] [[marine worm]]s) [[oligochaete]]s ([[microdrile]] worms), and [[Gastropoda|gastropod mollusks]] ([[sea slug]]s). [[Xenophyophore]]s 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.<ref name=EoE-seamount/> Many seamounts also have [[hydrothermal vent]] communities, for example [[Suiyo Seamount|Suiyo]]<ref>{{cite journal|last1=Higashi|first1=Y|title=Microbial diversity in hydrothermal surface to subsurface environments of Suiyo Seamount, Izu-Bonin Arc, using a catheter-type in situ growth chamber|journal=FEMS Microbiology Ecology|year=2004|volume=47|pmid=19712321|issue=3|pages=327–336|doi=10.1016/S0168-6496(04)00004-2|display-authors=etal|doi-access=free|bibcode=2004FEMME..47..327H}}</ref> and [[Kamaʻehuakanaloa Seamount|Kamaʻehuakanaloa]] seamounts.<ref name=FeMO-Intro>{{cite web |url=http://earthref.org/cgi-bin/er.cgi?s=http://earthref.org/FEMO/loihi.htm |title=Introduction to the Biology and Geology of Lōʻihi Seamount |work= Lōʻihi Seamount |publisher= Fe-Oxidizing Microbial Observatory (FeMO) |date=2009-02-01| access-date=2009-03-02}}</ref> This is helped by geochemical exchange between the seamounts and the ocean water.<ref name=oceanography-geo />

Seamounts may thus be vital stopping points for some [[animal migration|migratory animal]]s, specifically [[whale]]s. Some recent research indicates whales may use such features as navigational aids throughout their migration.<ref name=ask-sem>{{cite web|last=Kennedy|first=Jennifer|title=Seamount: What is a Seamount?|url=http://marinelife.about.com/od/glossary/g/seamountdef.htm|publisher=[[ask.com]]|access-date=25 July 2010|archive-date=7 August 2010|archive-url=https://web.archive.org/web/20100807002637/http://marinelife.about.com/od/glossary/g/seamountdef.htm}}</ref> For a long time it has been surmised that many [[Pelagic zone|pelagic animal]]s visit seamounts as well, to gather food, but proof of this aggregating effect has been lacking. The first demonstration of this conjecture was published in 2008.<ref name=marineecoprog>Morato, T., Varkey, D.A., Damaso, C., Machete, M., Santos, M., Prieto, R., Santos, R.S. and Pitcher, T.J. (2008). "Evidence of a seamount effect on aggregating visitors". ''Marine Ecology Progress'' Series 357: pages 23–32.</ref>

===Fishing===
The effect that seamounts have on fish populations has not gone unnoticed by the [[Commercial fishing|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.<ref name=ices>{{cite web|title=Seamounts – hotspots of marine life|url=http://www.ices.dk/marineworld/seamounts.asp|publisher=[[International Council for the Exploration of the Sea]]|access-date=24 July 2010|archive-url=https://web.archive.org/web/20100413164705/http://www.ices.dk/marineworld/seamounts.asp|archive-date=13 April 2010}}</ref>

Nearly 80 species of fish and shellfish are commercially harvested from seamounts, including [[spiny lobster]] (Palinuridae), [[mackerel]] (Scombridae and others), [[Paralithodes camtschaticus|red king crab]] (''Paralithodes camtschaticus''), [[Lutjanus campechanus|red snapper]] (''Lutjanus campechanus''), [[tuna]] (Scombridae), [[Orange roughy]] (''Hoplostethus atlanticus''), and [[perch]] (Percidae).<ref name=EoE-seamount/>

===Conservation===
[[File:Orange roughy.png|thumb|right|Because of overfishing at their seamount spawning grounds, stocks of [[orange roughy]] (''Hoplostethus atlanticus'') have plummeted; experts say that it could take decades for the species to restore itself to its former numbers.<ref name=ices/>]]

The ecological conservation of seamounts 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.<ref name=censeam-overview/> Much of this lack of information can be attributed to a lack of technology,{{Clarify|date=February 2014}} and to the daunting task of reaching these underwater structures; the technology to fully explore them has only been around the last few decades. Before consistent conservation efforts can begin, the seamounts of the world must first be [[Bathymetry|mapped]], a task that is still in progress.<ref name=EoE-seamount/>

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.<ref name=EoE-seamount/> The reason for this 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.<ref name=ices/> [[Bottom trawling]] in particular is extremely devastating to seamount ecology, and is responsible for as much as 95% of ecological damage to seamounts.<ref>Report of the [[Secretary-General of the United Nations|Secretary-General]] (2006) [https://www.un.org/Depts/los/general_assembly/documents/impact_of_fishing.pdf ''The Impacts of Fishing on Vulnerable Marine Ecosystems''] [[United Nations]]. 14 July 2006. Retrieved on 26 July 2010.</ref>

[[File:Koral1.jpg|thumb|left|[[Coral (precious)|Coral]] [[earrings]] of this type are often made from coral harvested off seamounts.]]

[[Coral]]s 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.<ref name=EoE-seamount/>

Individual nations are beginning to note the effect of fishing on seamounts, and the [[European Commission]] has agreed to fund the OASIS project, a detailed study of the effects of fishing on seamount communities in the [[North Atlantic]].<ref name=ices/> 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 a global understanding of seamount ecosystems, and the roles they have in the [[biogeography]], [[biodiversity]], [[Productivity (ecology)|productivity]] and [[evolution]] of marine organisms.<ref name=censeam-overview>{{cite web|title=CenSeam Mission|url=http://censeam.niwa.co.nz/censeam_about|publisher=CenSeam|access-date=22 July 2010|archive-url=https://web.archive.org/web/20100524081850/http://censeam.niwa.co.nz/censeam_about <!--Added by H3llBot-->|archive-date=24 May 2010}}</ref><ref name="censeam-science">{{cite web|title=CenSeam Science|url=http://censeam.niwa.co.nz/science|publisher=CenSeam|access-date=22 July 2010}}</ref>

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.<ref name="PLoS ONE-2009"/> One of the primary ecological havens on the seamount is its [[Deep water coral|deep sea coral]] garden, and many of the specimens noted were over a century old.<ref name=physorg.com/> Following the expansion of knowledge on the seamount there was extensive support to make it a [[Marine Protected Area|marine sanctuary]], a motion that was granted in 2008 as part of the [[Monterey Bay National Marine Sanctuary]].<ref name=noaa-pressrelease>{{cite web|url=http://cordellbank.noaa.gov/management/jmprpressrelease.pdf|title=NOAA Releases Plans for Managing and Protecting Cordell Bank, Gulf of Farallones and Monterey Bay National Marine Sanctuaries|date=November 20, 2008|work=Press release|publisher=[[NOAA]]|access-date=2 December 2009}}{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes}}</ref> Much of what is known about seamounts ecologically is based on observations from Davidson.<ref name=physorg.com/><ref name=marineecoprog/> Another such seamount is [[Bowie Seamount]], which has also been declared a marine protected area by Canada for its ecological richness.<ref name=ZO>{{cite web | title = Bowie Seamount Marine Protected Area | publisher = [[Fisheries and Oceans Canada]] |date=1 October 2011 | url = http://www.pac.dfo-mpo.gc.ca/oceans/protection/mpa-zpm/bowie/index-eng.htm |access-date=31 December 2011}}</ref>

==Exploration==
[[File:Sealevel chart.jpg|thumb|right|Graph showing the rise in global sea level (in mm) as measured by the [[NASA]]/[[CNES]] oceanic [[satellite altimeter]] [[TOPEX/Poseidon]] (left) and its follow-on mission [[Jason-1]]]]

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 the right technology available,{{Clarify|date=February 2014}} only a scant 1% of the total number have been explored,<ref name=seasci/> and sampling and information remains biased towards the top {{convert|500|m|ft|0|abbr=on}}.<ref name=EoE-seamount/> New species are observed or collected and valuable information is obtained on almost every [[submersible]] dive at seamounts.<ref name="seasci-sig">{{cite press release |title=Seamounts identified as significant, unexplored territory |url=https://www.sciencedaily.com/releases/2010/04/100430091605.htm |work=ScienceDaily |publisher=National Oceanic And Atmospheric Administration |date=30 April 2010 }}</ref>

Before seamounts and their oceanographic impact can be fully understood, they must be mapped, a daunting task due to their sheer number.<ref name=EoE-seamount/> The most detailed seamount mappings are provided by [[Multibeam echosounder|multibeam echosounding]] ([[sonar]]), however after more than 5000 publicly held cruises, the amount of the sea floor that has been mapped remains minuscule. [[Altimeter#Satellites|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 is that uncertainties in the technology limit recognition to features {{convert|1500|m|ft|0|abbr=on}} or larger. In the future, technological advances could allow for a larger and more detailed catalogue.<ref name="oceanography-census">{{cite journal |last1=Wessel |first1=Paul |last2=Sandwell |first2=David T. |last3=Kim |first3=Seung-Sep |title=The Global Seamount Census |journal=Oceanography |date=2010 |volume=23 |issue=1 |pages=24–33 |doi=10.5670/oceanog.2010.60 |jstor=24861056 |doi-access=free |bibcode=2010Ocgpy..23...24W }}</ref>

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.<ref>Amos, Jonathan. "[https://www.bbc.com/news/science-environment-29465446 Satellites detect 'thousands' of new ocean-bottom mountains]" ''[[BBC News]]'', 2 October 2014.</ref><ref>"[https://scripps.ucsd.edu/news/new-map-exposes-previously-unseen-details-seafloor New Map Exposes Previously Unseen Details of Seafloor]"</ref><ref>{{cite journal | last1 = Sandwell | first1 = David T. | last2 = Müller | first2 = R. Dietmar | last3 = Smith | first3 = Walter H. F. | last4 = Garcia | first4 = Emmanuel | last5 = Francis | first5 = Richard | year = 2014 | title = New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure | journal = Science | volume = 346 | issue = 6205| pages = 65–67 | doi = 10.1126/science.1258213 | pmid=25278606| bibcode = 2014Sci...346...65S | s2cid = 31851740 }}</ref><ref>"[http://www.space.dtu.dk/english/Research/Projects/Cryosat_4Plus Cryosat 4 Plus]" ''[[DTU Space]]''</ref>

== Deep-sea mining ==
Seamounts are a possible future source of economically important metals. Even though 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.<ref name="oceanography-mining">{{cite journal|author1=James R. Hein|author2=Tracy A. Conrad|author3=Hubert Staudigel|title=Seamount Mineral Deposits: A Source for Rare Minerals for High Technology Industries|journal=[[Oceanography (journal)|Oceanography]]|volume=23|series=Seamounts Special Issue|issue=1|url=http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/23_1/23-1_hein.pdf|access-date=26 July 2010|issn=1042-8275|archive-url=https://web.archive.org/web/20100613135224/http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/23_1/23-1_hein.pdf|archive-date=13 June 2010}}</ref>

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 the seafloor is Conical Seamount, located about 8&nbsp;km south of [[Lihir Island]] in Papua New Guinea. Conical Seamount has a basal diameter of about 2.8&nbsp;km and rises about 600&nbsp;m above the seafloor to a water depth of 1050&nbsp;m. Grab samples from its summit contain the highest gold concentrations yet reported from the modern seafloor (max. 230&nbsp;g/t Au, avg. 26&nbsp;g/t, n=40).<ref>{{cite journal|last=Muller|first=Daniel |author2=Leander Franz |author3=Sven Petersen |author4=Peter Herzig |author5=Mark Hannington|date=2003|title=Comparison between magmatic activity and gold mineralization at Conical Seamount and Lihir Island, Papua New Guinea|journal=Mineralogy and Petrology|volume=79|issue=3–4 |pages=259–283|bibcode=2003MinPe..79..259M|doi=10.1007/s00710-003-0007-3|s2cid=129643758 }}</ref>  [[Iron]]-[[manganese]], [[hydrothermal vent|hydrothermal]] [[iron oxide]], [[Sulfide minerals|sulfide]], [[Sulfate minerals|sulfate]], [[sulfur]], hydrothermal <!-- dab intentional -->[[manganese oxide]], and [[phosphorite]]<ref>C.Michael Hogan. 2011. [http://www.eoearth.org/article/Phosphate?topic=49557 ''Phosphate''. Encyclopedia of Earth. Topic ed. Andy Jorgensen. Ed.-in-Chief C.J.Cleveland. National Council for Science and the Environment. Washington DC]</ref> (the latter especially in parts of Micronesia) are all mineral resources that are deposited upon or within seamounts. However, only the first two have any potential of being targeted by mining in the next few decades.<ref name="oceanography-mining"/>

== Dangers ==
[[File:US Navy 050127-N-4658L-030 The Los Angeles-class fast-attack submarine USS San Francisco (SSN 711) in dry dock to assess damage sustained after running aground approximately 350 miles south of Guam Jan. 8, 2005.jpg|thumb|right|[[USS San Francisco (SSN-711)|USS ''San Francisco'']] in [[dry dock]] in [[Guam]] in January 2005, following its collision with an uncharted seamount. The damage was extensive and the submarine was just barely salvaged.<ref name="ssn711"/>]]

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.<ref>{{cite book|author=Nigel Calder|title=How to Read a Navigational Chart: A Complete Guide to the Symbols, Abbreviations, and Data Displayed on Nautical Charts|publisher=International Marine/Ragged Mountain Press|year=2002}}</ref> More recently, the submarine [[USS San Francisco (SSN-711)|USS ''San Francisco'']] ran into an uncharted seamount in 2005 at a speed of {{convert|35|kn|mph km/h|1}}, sustaining serious damage and killing one seaman.<ref name="ssn711">{{cite web|title=USS San Francisco (SSN 711)|url=http://www.ssbn611.org/uss_san_francisco.htm|access-date=25 July 2010|archive-url=https://web.archive.org/web/20090925023959/http://www.ssbn611.org/uss_san_francisco.htm|archive-date=25 September 2009}}</ref>

One major seamount risk is that often, in the late of stages of their life, [[extrusive|extrusion]]s begin to seep in the seamount. This activity leads to inflation, over-extension of the volcano's flanks, and ultimately [[Volcanic landslide#Flank collapses|flank collapse]], leading to submarine [[landslide]]s with the potential to start major [[tsunami]]s, which can be among the largest natural disasters in the world. In an illustration of the potent power of flank collapses, a summit collapse on the northern edge of [[Vlinder Seamount]] resulted in a pronounced [[headwall]] [[Escarpment|scarp]] and a field of debris up to {{convert|6|km|mi|0|abbr=on}} away.<ref name=oceanography-geo /> A catastrophic collapse at [[Detroit Seamount]] flattened its whole structure extensively.<ref name="Stanford-2005" /> Lastly, in 2004, scientists found [[Fossil|marine fossil]]s {{convert|61|m|ft|0|abbr=on}} up the flank of [[Kohala (mountain)|Kohala mountain]] in [[Hawaii (island)|Hawaii]]. Subsidation analysis found that at the time of their deposition, this would have been {{convert|500|m|ft|0|abbr=on}} up the flank of the volcano,<ref name="John Seach-Kohala">{{cite web|url=http://www.volcanolive.com/kohala.html|title=Kohala Volcano |last=Seach|first=John|work=Volcanism reference base|publisher=[[John Seach]], vulcanologist|access-date=25 July 2010}}</ref> 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.<ref name="NS">{{cite journal | title = Hawaiian tsunami left a gift at foot of volcano | journal = [[New Scientist]] | issue = 2464 | page = 14 | date = 2004-09-11 | url =https://www.newscientist.com/article/mg18324641.900-hawaiian-tsunami-left-a-gift-at-foot-of-volcano.html | access-date = 25 July 2010}}</ref>

==See also==
{{Portal|Oceans}}
{{Div col}}
* [[Asphalt volcano]]
* [[Bathymetry]]
* [[Evolution of Hawaiian volcanoes]]
* [[Hotspot (geology)]]
* [[List of submarine volcanoes]]
* [[Marine protected area]]
* [[Mud volcano]]
* [[Oceanic trench]]
* [[Submarine eruption]]
* [[Submarine volcano]]
* [[Topographic prominence]]
* [[Volcanic island]]
{{Div col end}}

== References ==
{{Reflist}}

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==Bibliography==
'''Geology'''
* Keating, B.H., Fryer, P., Batiza, R., Boehlert, G.W. (Eds.), 1987: ''[https://books.google.com/books?id=u-NMJaicckMC&q=Seamounts,+islands+and+atolls Seamounts, islands and atolls]''. Geophys. Monogr. 43:319–334.
* Menard, H.W. (1964). ''[http://adsabs.harvard.edu/abs/1964Sci...146..513M Marine Geology of the Pacific]''. International Series in the Earth Sciences. McGraw-Hill, New York, 271 pp.

'''Ecology'''
* {{Cite journal | last1 = Clark | first1 = M. R. | last2 = Rowden | first2 = A. A. | last3 = Schlacher | first3 = T. | last4 = Williams | first4 = A. | last5 = Consalvey | first5 = M. | last6 = Stocks | first6 = K. I. | last7 = Rogers | first7 = A. D. | last8 = O'Hara | first8 = T. D. | last9 = White | first9 = M. | last10 = Shank | first10 = T. M. | last11 = Hall-Spencer | first11 = J. M. | title = The Ecology of Seamounts: Structure, Function, and Human Impacts | doi = 10.1146/annurev-marine-120308-081109 | journal = Annual Review of Marine Science | volume = 2 | pages = 253–278 | year = 2010 | pmid =  21141665| bibcode = 2010ARMS....2..253C | hdl = 10026.1/1339 | hdl-access = free }}
* {{cite journal|author1=Richer de Forges |author2=J. Anthony Koslow |author3=G. C. B. Poore  |name-list-style=amp |title =Diversity and endemism of the benthic seamount fauna in the southwest Pacific|journal=[[Nature (journal)|Nature]]|volume=405|issue=6789|pages=944–947|date=22 June 2000|doi=10.1038/35016066|pmid =10879534|bibcode=2000Natur.405..944R |s2cid=4382477 }}
* {{cite journal | last1 = Koslow | first1 = J.A. | year = 1997 | title = Seamounts and the ecology of deep-sea fisheries | url = http://wwf.panda.org/about_our_earth/blue_planet/deep_sea/seamounts/ | journal = Am. Sci. | volume = 85 | issue = 2| pages = 168–176 | bibcode = 1997AmSci..85..168K }}
*{{cite journal | last1 = Lundsten | first1 = L | last2 = McClain | first2 = CR | last3 = Barry | first3 = JP | last4 = Cailliet | first4 = GM | last5 = Clague | first5 = DA | last6 = DeVogelaere | first6 = AP | year = 2009 | title = Ichthyofauna on Three Seamounts off Southern and Central California, USA | journal = Marine Ecology Progress Series | volume = 389 | pages = 223–232 | doi=10.3354/meps08181| bibcode = 2009MEPS..389..223L | doi-access = free }}
* Pitcher, T.J., Morato, T., Hart, P.J.B., Clark, M.R., Haggan, N. and Santos, R.S. (eds) (2007). "[http://www.wiley.com/WileyCDA/WileyTitle/productCd-1405133430.html Seamounts: Ecology, Fisheries and Conservation]". ''Fish and Aquatic Resources'' Series 12, Blackwell, Oxford, UK. 527pp.  {{ISBN|978-1-4051-3343-2}}
<!-- papers, databases, and resources that are fully online are listed here -->

== External links ==
'''Geography and geology'''
*[http://earthref.org/databases/SC/ Earthref Seamount Catalogue]. A database of seamount maps and catalogue listings.
*[http://oceanexplorer.noaa.gov/explorations/02alaska/background/geology/geology.html Volcanic History of Seamounts in the Gulf of Alaska].
* [http://www.agu.org/pubs/crossref/2001/2001JB900004.shtml The giant Ruatoria debris avalanche on the northern Hikurangi margin, New Zealand] {{Webarchive|url=https://web.archive.org/web/20100716025516/http://www.agu.org/pubs/crossref/2001/2001JB900004.shtml |date=2010-07-16 }}. Aftermath of a seamount carving into the far side of a subduction trench.
*[https://hvo.wr.usgs.gov/volcanowatch/1995/95_09_08.html Evolution of Hawaiian volcanoes]. The life cycle of seamounts was originally observed off of the Hawaiian arc.
*[http://www.geology.sdsu.edu/how_volcanoes_work/lava_water.html How Volcanoes Work: Lava and Water]. An explanation of the different types of lava-water interactions.

'''Ecology'''
*[https://web.archive.org/web/20081002142904/http://swfsc.noaa.gov/publications/CR/1987/8709.PDF A review of the effects of seamounts on biological processes].{{dead link|date=September 2024}} NOAA paper.
*[https://web.archive.org/web/20100604013937/http://www.tos.org/oceanography/issues/issue_archive/23_1.html Mountains in the Sea], a volume on the biological and geological effects of seamounts, available fully online.
*[http://seamounts.sdsc.edu SeamountsOnline], seamount biology database.
*[http://www.unep-wcmc.org/resources/publications/UNEP_WCMC_bio_series/25.htm Vulnerability of deep sea corals to fishing on seamounts beyond areas of national jurisdiction] {{Webarchive|url=https://web.archive.org/web/20070627233726/http://www.unep-wcmc.org/resources/publications/UNEP_WCMC_bio_series/25.htm |date=2007-06-27 }}, United Nations Environment Program.

{{physical oceanography|expanded=other}}
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[[Category:Seamounts|*]]
[[Category:Physical oceanography]]
[[Category:Fisheries science]]