Editing Cold seep (section)

== Distribution ==

Cold seeps were discovered in 1983 by Charles Paull and colleagues on the Florida Escarpment in the [[Gulf of Mexico]] at a depth of {{convert|3200|m|ft|sp=us}}.<ref>{{cite journal |author1=Paull |author2=Hecker |author3=Commeau |author4=Freeman-Lynde |author5=Neumann |author6=Corso |author7=Golubic |author8=Hook |author9=Sikes |author10=Curray |display-authors=3 | year=1984 | title=Biological communities at the Florida escarpment resemble hydrothermal vent taxa | journal=Science | volume=226 | issue=4677 | pages=965–967 | doi=10.1126/science.226.4677.965| pmid=17737352 | bibcode=1984Sci...226..965P |s2cid=45699993 }}</ref> Since then, seeps have been discovered in many other parts of the world's oceans. Most have been grouped into five [[biogeographic]] provinces: Gulf of Mexico, Atlantic, Mediterranean, East Pacific, and West Pacific,<ref name="Olu 2010" /> but cold seeps are also known from under the [[ice shelf]] in [[Antarctica]],<ref>{{cite web |url = https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=109683 |title = Demise of Antarctic Ice Shelf Reveals New Life |publisher = [[National Science Foundation]] |year = 2007 |access-date = 14 February 2008 }}</ref> the [[Arctic Ocean]], the [[North Sea]], [[Skagerrak]], [[Kattegat]], the [[Gulf of California]], the [[Red Sea]], the [[Indian Ocean]], off [[southern Australia]], and in the inland [[Caspian Sea]].<ref name=Levin2005>{{cite book| author=Levin, L.A. | year=2005 | chapter=Ecology of cold seep sediments: Interactions if fauna with flow, chemistry and microbes | pages=1–46 | editor1=Gibson, R.N. |editor2=R.J.A. Atkinson |editor3=J.D.M. Gordon | title=Oceanography and Marine Biology: An Annual Review | volume=43 | publisher=Taylor & Francis | isbn=9780849335976}}</ref> In the [[Pacific Northwest]], a cold seep called [[Pythia's Oasis]] was discovered in 2015.<ref>{{cite web |title=Pythias Oasis: An Underwater Spring Unlike Any Other |url=https://interactiveoceans.washington.edu/10/2019/pythias-oasis-an-underwater-spring-unlike-any-other/ |website=OOI Regional Cable Array |publisher=University of Washington |access-date=24 April 2023 |date=1 October 2019}}</ref> With the recent discovery of a methane seep in the [[Southern Ocean]],<ref name="Domack 2005">{{cite journal | last1 = Domack | first1 = E. | author-link = Eugene Domack | last2 = Ishman | first2 = S. | last3 = Leventer | first3 = A. | last4 = Sylva | first4 = S. | last5 = Willmott | first5 = V.   | s2cid = 35944740 | year = 2005 | title = A chemotrophic ecosystem found beneath Antarctic Ice Shelf | journal = [[Eos (newspaper)|Eos, Transactions American Geophysical Union]] | volume = 86 | issue = 29| pages = 269–276 | doi = 10.1029/2005EO290001 | bibcode=2005EOSTr..86..269D| doi-access = free }}</ref> cold seeps are now known in all major oceans.<ref name="Bernardino 2012" />  Cold seeps are common along continental margins in areas of high primary productivity and tectonic activity, where crustal deformation and compaction drive emissions of methane-rich fluid.<ref name="Bernardino 2012" /> Cold seeps are patchily distributed, and they occur most frequently near ocean margins from [[intertidal]] to [[hadal]] depths.<ref name="Bernardino 2012" /> In Chile, cold seeps are known from the intertidal zone,<ref>{{cite journal| author1=Jessen |author2=Pantoja |author3=Gutierréz |author4=Quiñones |author5=González |author6=Sellanes |author7=Kellermanns |author8=Hinrichs |display-authors=3 | year=2011 | title=Methane in shallow cold seeps at Mocha Island off central Chile | journal=Continental Shelf Research | volume=31 | issue=6 | pages=574–581 | doi=10.1016/j.csr.2010.12.012| bibcode=2011CSR....31..574J | hdl=10533/129437 | hdl-access=free }}</ref> in Kattegat, the methane seeps are known as "bubbling reefs" and are typically at depths of {{convert|0|-|30|m|ft|abbr=on|-2}},<ref name=HelcomCS>{{cite web|url=http://helcom.fi/Red%20List%20of%20biotopes%20habitats%20and%20biotope%20complexe/HELCOM%20Red%20List%201180%20Submarine%20structures%20made%20by%20leaking%20gases.pdf | title=Red List – Submarine structures made by leaking gases | publisher=[[HELCOM]] | year=2013 | access-date=16 June 2017}}</ref> and off northern California, they can be found as shallow as {{convert|35|-|55|m|ft|abbr=on}}.<ref name=Levin2005/> Most cold seeps are located considerably deeper, well beyond the reach of ordinary [[scuba diving]], and the deepest seep community known is found in the [[Japan Trench]] at a depth of {{convert|7326|m|ft|abbr=on}}.<ref>{{cite journal| author1=Fujikura |author2=Kojima |author3=Tamaki |author4=Maki |author5=Hunt |author6=Okutani |display-authors=3 | year=1999 | title=The deepest chemosynthesis-based community yet discovered from the hadal zone, 7326 m deep, in the Japan Trench | journal=Marine Ecology Progress Series | volume=190 | pages=17–26 | doi=10.3354/meps190017| bibcode=1999MEPS..190...17F | doi-access=free }}</ref>

In addition to cold seeps existing today, the fossil remains of ancient seep systems have been found in several parts of the world. Some of these are located far inland in places formerly covered by [[prehistoric ocean]]s.<ref name=Levin2005/><ref>{{cite journal| author1=Campbell, K.A. |author2=J.D. Farmer |author3=D. Des Marais | year=2002 | title=Ancient hydrocarbon seeps from the Mesozoic convergent margin of California: carbonate geochemistry, fluids and palaeoenvironments | journal=Geofluids | volume=2 | issue=2 | pages=63–94 | doi=10.1046/j.1468-8123.2002.00022.x| doi-access=free |bibcode=2002Gflui...2...63C }}</ref>

=== In the Gulf of Mexico ===

[[File:ALVIN submersible.jpg|thumb|The crewed submersible ''[[DSV Alvin]]'', which made possible the discovery of chemosynthetic communities in the Gulf of Mexico in 1983.]]

==== Discoveries ====

The chemosynthetic communities of the Gulf of Mexico have been studied extensively since the 1990s, and communities first discovered on the upper slope are likely the best understood seep communities in the world. The history of the discovery of these remarkable animals has all occurred since the 1980s. Each major discovery was unexpected―from the first hydrothermal vent communities anywhere in the world to the first cold seep communities in the [[Gulf of Mexico]].<ref name="MMS 2006" />

Communities were discovered in the eastern Gulf of Mexico in 1983 using the crewed submersible ''[[DSV Alvin]]'', during a cruise investigating the bottom of the [[Florida Escarpment]] in areas of "cold" brine seepage, where they unexpectedly discovered [[Lamellibrachia|tubeworms]] and mussels.<ref>{{cite journal | author1 = Pauli C.K.  | author2 = Hecker B. | author3 = Commeau R. | author4 = Freeman-Lynde R. | author5 = Neumann C. |author6 = Corso W. | author7= Golubic S. | author8=Hook J.E. | author9=Sikes E.L. |author10=Curray J.R. | year = 1984 | title = Biological Communities at the Florida Escarpment Resemble Hydrothermal Vent Taxa | journal = Science | volume = 226 | issue = 4677| pages = 965–967 | doi = 10.1126/science.226.4677.965| pmid = 17737352 | bibcode = 1984Sci...226..965P }}</ref><ref name="MMS 2006" /> Two groups fortuitously discovered chemosynthetic communities in the central Gulf of Mexico nearly concurrently in November and December 1984. During investigations in late December on the  research vessel R/V ''Gyre'' cruise 84-G-12, by [[Texas A&M University]], two bottom trawls were conducted to determine the effects of [[oil seep]]age on [[benthic ecology]] (until this investigation, all effects of oil seepage were assumed to be detrimental). Trawls unexpectedly recovered extensive collections of chemosynthetic organisms, including tubeworms and clams.<ref>{{cite journal | author1 = Kennicutt M.  | author2 = Brooks J. | author3 = Bidigare R.R. | author4 = Fay R.R. | author5 = Wade T.L. |author6 = McDonald T.J. | year = 1985 | title = Vent-type taxa in a hydrocarbon seep region on the Louisiana slope | journal = Nature | volume = 317 | issue = 6035| pages = 351–353 | doi = 10.1038/317351a0| bibcode = 1985Natur.317..351K }}</ref> a month earlier, LGL Ecological Research Associates was conducting a research cruise as part of the multiyear [[Minerals Management Service|MMS]] Northern Gulf of Mexico Continental Slope Study  (Gallaway et al., 1988<ref>Gallaway, B.J., L.R. Martin, L.R., Howard R.L (Eds.). 1988a. Northern Gulf of Mexico Continental Slope Study, Annual Report: Year 3. Volume II: Technical Narrative. Annual report submitted to the Minerals Management Service, New Orleans, LA. Contract No. 14-12-0001-3212. OCS Study/MMS 87-0060. 586 pp. https://espis.boem.gov/final%20reports/3774.pdf</ref>). Bottom photography as part of this project obtained images from the end of a film roll of a deep-sea camera sled (processed on board the vessel November 14, 1984) that resulted in clear images of [[Vesicomyidae|vesicomyid]] clam chemosynthetic communities (Rossman et al., 1987<ref>Rosman, I., Boland, G.S., Baker, J.S. 1987.  Aggregations of Vesicomyidae on the continental slope off Louisiana. Deep-Sea Res. 34(11): 1811-1820.</ref>) coincidentally in the same manner as the first documentation of chemosynthetic communities at the Galapagos Rift investigating hot water plumes by camera sled in the Pacific in 1976 (Lonsdale 1977<ref>Lonsdale, P. 1977. Clustering of suspension-feeding macrobenthos near abyssal hydrothermal vents at oceanic spreading centers. Deep-Sea Res., 24(9), 857-863.</ref>). Photography during the same LGL/MMS cruise also documented tube-worm communities in situ in the Central Gulf of Mexico for the first time (not processed until after the cruise; Boland, 1986<ref>Boland, G.S. 1986. Discovery of co-occurring bivalve Acesta sp. and chemosynthetic tube worms Lamellibrachia sp. (Photograph and text). Nature, 323 (6091): 759</ref>) prior to the initial submersible investigations and firsthand descriptions of [[Green Canyon|Bush Hill]] ({{coord|27|47|02|N|91|30|31|W|name=Bush Hill}}) in 1986.<ref>{{cite journal | author1 = Rosman I. | author2 = Boland G.S. | author3 = Baker J.S. | year = 1987 | title = Epifaunal aggregations of Vesicomyidae on the continental slope off Louisiana | journal = Deep Sea Research Part A. Oceanographic Research Papers | volume = 34 | issue = 11 | pages = 1811–1820 | doi = 10.1016/0198-0149(87)90055-0| bibcode = 1987DSRA...34.1811R }}</ref><ref>{{cite journal | author1 = MacDonald I.R.  | author2 = Boland G.S. | author3 = Baker J.S. | author4 = Brooks J.M. | author5 = Kennicutt M.C. |author6 = Bidigare R.R. | year = 1989 | title = Gulf of Mexico hydrocarbon seep communities II Spatial distribution of seep organisms and hydrocarbons at Bush Hill | journal = Marine Biology | volume = 101| issue = 2 | pages = 235–247 | doi = 10.1007/BF00391463| bibcode = 1989MarBi.101..235M }}</ref> The Bush Hill site was targeted by acoustic "wipeout" zones or lack of substrate structure caused by seeping hydrocarbons. This was determined using an acoustic pinger system during the same cruise on the R/V ''Edwin Link'' (renamed from ''Sea Diver'' and only 113&nbsp;ft (34&nbsp;m)), which used one of the ''[[Johnson Sea Link]]'' submersibles. This site represents the first eyes-on human observations of chemosynthetic communities in the northern Gulf of Mexico and is characterized by dense tubeworm and mussel accumulations, as well as exposed carbonate outcrops with numerous [[gorgonia]]n and ''[[Lophelia]]'' coral colonies. Bush Hill has become one of the most thoroughly-studied chemosynthetic sites in the world.<ref name="MMS 2006" />

==== Distribution ====

[[File:Chemosynthetic communities in the Gulf of Mexico 2000.png|thumb|Chemosynthetic communities in the northern part of Gulf of Mexico around cold seeps known in 2000]]

There is a clear relationship between known hydrocarbon discoveries at great depth in the Gulf slope and chemosynthetic communities, hydrocarbon seepage, and [[Authigenesis|authigenic]] minerals including carbonates at the seafloor.<ref name=Sassen1993>{{cite journal |author1 = Sassen R. | author2 = Roberts H.| author3= Aharon P. | author4= Larkin J. | author5= Chinn E.W. | author6= Carney R.S. |year = 1993 |title = Chemosynthetic bacterial mats at cold hydrocarbon seeps, Gulf of Mexico continental slope |doi = 10.1016/0146-6380(93)90083-N |journal = Organic Geochemistry |pages = 77–89 |volume=20 |issue = 1 | bibcode = 1993OrGeo..20...77S}}</ref> While the hydrocarbon reservoirs are broad areas several kilometers beneath the Gulf, chemosynthetic communities occur in isolated areas with thin veneers of sediment only a few meters thick.<ref name="MMS 2006" />

The northern Gulf of Mexico slope includes a [[stratigraphic section]] more than 10&nbsp;km (6&nbsp;mi) thick and has been profoundly influenced by [[Salt tectonics|salt movement]]. [[Mesozoic]] source rocks from [[Upper Jurassic]] to [[Upper Cretaceous]] generate oil in most of the Gulf slope fields.<ref name=Sassen1993/> Migration conduits supply fresh hydrocarbon materials through a vertical scale of 6–8&nbsp;km (4–5&nbsp;mi) toward the surface. The surface expressions of hydrocarbon migration are called seeps. Geological evidence demonstrates that hydrocarbon and brine seepage persists in spatially discrete areas for thousands of years.<ref name="MMS 2006" />

The time scale for oil and gas migration from source systems is on the scale of millions of years (Sassen, 1997). Seepage from hydrocarbon sources through faults towards the surface tends to be diffused through the overlying sediment, carbonate outcroppings, and [[hydrate]] deposits, so the corresponding hydrocarbon seep communities tend to be larger (a few hundred meters wide) than chemosynthetic communities found around the hydrothermal vents of the [[Eastern Pacific]] (MacDonald, 1992).<ref name="MMS 2006" /> There are large differences in the concentrations of hydrocarbons at seep sites. Roberts (2001) presented a spectrum of responses to be expected under a variety of flux rate conditions varying from very slow seepage to rapid venting.<ref name="MMS 2006" /><ref>{{cite book|last=Roberts |first=H. H. |year=2001 |chapter-url=http://www.agu.org/books/gm/v124/GM124p0145/GM124p0145.shtml |chapter=Fluid and gas expulsion on the northern Gulf of Mexico continental slope: Mud-prone to mineral-prone responses |doi=10.1029/GM124p0145 |volume=124 |publisher=[[American Geophysical Union]] |pages=145–161 |access-date=26 March 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121028142946/http://www.agu.org/books/gm/v124/GM124p0145/GM124p0145.shtml |archive-date=28 October 2012 |df=dmy |bibcode=2001GMS...124..145R |series=Geophysical Monograph Series |isbn=9781118668412 |title=Natural Gas Hydrates }}</ref> Very-slow-seepage sites do not support complex chemosynthetic communities; rather, they usually only support simple [[bacterial mat|microbial mats]] (''[[Beggiatoa]]'' sp.).<ref name="MMS 2006" />

In the upper slope environment, the hard substrates resulting from carbonate precipitation can have associated communities of non-chemosynthetic animals, including a variety of sessile [[cnidarian]]s such as [[coral]]s and [[sea anemone]]s. At the rapid flux end of the spectrum, [[Fluidization|fluidized]] sediment generally accompanies hydrocarbons and formation fluids arriving at the seafloor. [[Mud volcano]]es and [[mud flow]]s result. Somewhere between these two end members exists the conditions that support densely populated and diverse communities of chemosynthetic organisms (microbial mats, [[Siboglinidae|siboglinid]] tube worms, [[Bathymodiolus|bathymodioline]] mussels, [[Lucinidae|lucinid]] and [[Vesicomyidae|vesicomyid]] clams, and associated organisms). These areas are frequently associated with surface or near-surface [[gas hydrate]] deposits. They also have localized areas of lithified seafloor, generally authigenic carbonates but sometimes more exotic minerals such as [[barite]] are present.<ref name="MMS 2006" />

[[File:Chemosynthetic communities in the Gulf of Mexico 2006.png|thumb|Chemosynthetic communities in the northern part of Gulf of Mexico around cold seeps known in 2006 include more than 50 communities]]
The widespread nature of Gulf of Mexico chemosynthetic communities was first documented during contracted investigations by the Geological and Environmental Research Group (GERG) of Texas A&M University for the Offshore Operators Committee.<ref>{{cite journal |author1= Brooks J. |author2 = Cox H.B. |author3 = Bryant W. |author4 = Kennicutt M. |author5 = Mann R.G. |author6 = McDonald T.J. |year = 1986 |title = Association of Gas Hydrates and Oil Seepage in the Gulf-of-Mexico |doi = 10.1016/0146-6380(86)90025-2|journal = Organic Geochemistry |pages = 221-234 |volume=10 |issue = 1-3 }}</ref><ref name="MMS 2006" /> This survey remains the most widespread and comprehensive, although numerous additional communities have been documented since that time.<ref name="MMS 2006" /> Industry exploration for [[Offshore oil and gas in the US Gulf of Mexico|energy reserves in the Gulf of Mexico]] has also documented numerous new communities through a wide range of depths, including the deepest-known occurrence in the Central Gulf of Mexico in Alaminos Canyon Block 818 at a depth of 2,750&nbsp;m (9,022&nbsp;ft).<ref name="MMS 2006" /> The occurrence of chemosynthetic organisms dependent on hydrocarbon seepage has been documented in water depths as shallow as 290&nbsp;m (951&nbsp;ft)<ref>{{cite journal |author1= Roberts H. |author2 = Aharon P. |author3 = Carney R.S. |author4 = Larkin J. |author5 = Sassen R. |date = 1990 |title = Sea floor responses to hydrocarbon seeps, Louisiana continental slope |doi = 10.1007/BF02431070|journal = Geo-Marine Letters |pages = 232-243 |volume=10 |issue= 4 }}</ref> and as deep as 2,744&nbsp;m (9,003&nbsp;ft).<ref name="MMS 2006" /> This depth range specifically places chemosynthetic communities in the deepwater region of the Gulf of Mexico, which is defined as water depths greater than 305&nbsp;m (1,000&nbsp;ft).<ref name="MMS 2006" />

Chemosynthetic communities are not found on the [[continental shelf]], although they do appear in the fossil record in water shallower than 200&nbsp;m (656&nbsp;ft).<ref name="MMS 2006" /> One theory explaining this is that [[predation]] pressure has varied substantially over the time period involved (Callender and Powell 1999).<ref name="MMS 2006" /><ref>{{cite journal |last = Callender |first = W. Russell |author2 = E. N. Powell |year = 1999 |title = Why did ancient chemosynthetic seep and vent assemblages occur in shallower water than they do today? |doi = 10.1007/s005310050273 |journal = International Journal of Earth Sciences |pages = 377–391 |volume=88|issue = 3 |bibcode = 1999IJEaS..88..377C |s2cid = 140681313 }}</ref> More than 50 communities are now known to exist in 43 [[Outer Continental Shelf]] (OCS) blocks.<ref name="MMS 2006" /> Although a systematic survey has not been done to identify all chemosynthetic communities in the Gulf of Mexico, there is evidence indicating that many more such communities may exist.<ref name="MMS 2006" /> The depth limits of discoveries probably reflect the limits of exploration (lack of [[submersibles]] capable of depths over 1,000&nbsp;m (3,281&nbsp;ft)).<ref name="MMS 2006" />

MacDonald et al. (1993 and 1996) have analyzed [[remote-sensing]] images from space that reveal the presence of [[oil slick]]s across the north-central Gulf of Mexico.<ref name="MMS 2006" /><ref>{{cite journal |doi=10.1029/93JC01289 |bibcode=1993JGR....9816351M |title=Natural oil slicks in the Gulf of Mexico visible from space |journal=Journal of Geophysical Research |volume=98 |issue=C9 |pages=16351 |year=1993 |last1=MacDonald |first1=I. R. |last2=Guinasso |first2=N. L. |last3=Ackleson |first3=S. G. |last4=Amos |first4=J. F. |last5=Duckworth |first5=R. |last6=Sassen |first6=R. |last7=Brooks |first7=J. M. }}</ref><ref name=McDonald96>{{Cite book |last = MacDonald |first = I.R. |author2 = J.F. Reilly Jr. |author3 = W.E. Best |author4 = R. Vnkataramaiah |author5 = R. Sassen |author6 = N.S. Guinasso Jr. |author7 = J. Amos |year = 1996 |title = Remote sensing inventory of active oil seeps and chemosynthetic communities in the northern |work = Gulf of Mexico. In: Schumacher, D. and M.A. Abrams, eds. Hydrocarbon migration and its nearsurface expression. American Association of Petroleum Geologists Memoir 6 |publisher = Amer Association of Petroleum Geologists |isbn = 978-0-89181-345-3 |pages = 27–37 }}</ref> Results confirmed extensive natural oil seepage in the Gulf of Mexico, especially in water depths greater than 1,000&nbsp;m (3,281&nbsp;ft).<ref name="MMS 2006" /> A total of 58 additional potential locations were documented where seafloor sources were capable of producing perennial oil slicks.<ref name=McDonald96/><ref name="MMS 2006" /> Estimated seepage rates ranged from {{convert|4|oilbbl/d|abbr=on}} to {{convert|70|oilbbl/d|abbr=on}} compared to less than {{convert|0.1|oilbbl/d|abbr=on}} for ship discharges (both normalized for 1,000&nbsp;mi<sup>2</sup> (640,000 ac)).<ref name="MMS 2006" /> This evidence considerably increases the area where chemosynthetic communities dependent on hydrocarbon seepage may be expected.<ref name="MMS 2006" />

The densest aggregations of chemosynthetic organisms have been found at water depths of around 500&nbsp;m (1,640&nbsp;ft) and deeper. The best known of these communities was named Bush Hill by the investigators who first described it.<ref name=Macdonald89>{{cite journal |title=Gulf of Mexico hydrocarbon seep communities: II. Spatial distribution of seep organisms and hydrocarbons at Bush Hill |journal=Marine Biology |volume=101 |pages=235-247 |year=1989 |last1=MacDonald |first1=I. R. |last2=Boland |first2=G. S. |last3=Baker |first3=J. S. |last4=Brooks |first4=J. M. |last5=Kennicutt II |first5=M. C. |last6=Bidigare  |first6=R. R. }}</ref><ref name="MMS 2006" /> It is a surprisingly large and dense community of chemosynthetic tube worms and mussels at a site of natural petroleum and gas seepage over a [[salt diapir]] in Green Canyon Block 185. The seep site is a small knoll that rises about 40&nbsp;m (131&nbsp;ft) above the surrounding seafloor in about 580-m (1,903-ft) water depth.<ref name="MMS 2006" />

==== Stability ====

According to Sassen (1997) the role of [[hydrate]]s at chemosynthetic communities has been greatly underestimated.<ref name="MMS 2006" /> The biological alteration of frozen [[gas hydrate]]s was first discovered during the [[Minerals Management Service|MMS]] study entitled "Stability and Change in Gulf of Mexico Chemosynthetic Communities".<ref name="ir mcdonald">{{cite web |editor1 = I. R. McDonald |title = Stability and Change in Gulf of Mexico Chemosynthetic Communities |url = https://www.data.boem.gov/PI/PDFImages/ESPIS/3/3227.pdf |publisher = U.S. Department of the Interior: OCS Study MMS 98-0034: Prepared by the Geochemical and Environmental Research Group: Texas A&M University |access-date = 17 July 2016 |date = 1998 |archive-date = 29 December 2016 |archive-url = https://web.archive.org/web/20161229022053/https://www.data.boem.gov/PI/PDFImages/ESPIS/3/3227.pdf |url-status = dead }}</ref> It is hypothesized<ref name=Macdonald89/> that the dynamics of hydrate alteration could play a major role as a mechanism for regulation of the release of hydrocarbon gases to fuel biogeochemical processes and could also play a substantial role in community stability. Recorded bottom-water temperature excursions of several degrees in some areas such as the Bush Hill site (4–5&nbsp;°C at 500-m (1,640-ft) depth) are believed to result in dissociation of hydrates, resulting in an increase in gas fluxes (MacDonald et al., 1994). Although not as destructive as the [[volcanism]] at vent sites of the [[mid-ocean ridge]]s, the dynamics of shallow hydrate formation and movement will clearly affect [[Sessility (motility)|sessile animals]] that form part of the seepage barrier. There is potential of a catastrophic event where an entire layer of shallow hydrate could break free of the bottom and considerably affect local communities of chemosynthetic fauna.<ref name="MMS 2006" /> At deeper depths (>1,000 m, >3,281&nbsp;ft), the bottom-water temperature is colder (by approximately 3&nbsp;°C) and undergoes less fluctuation. The formation of more stable and probably-deeper hydrates influences the flux of light hydrocarbon gases to the sediment surface, thus influencing the surface morphology and characteristics of chemosynthetic communities. Within complex communities such as Bush Hill, <!--oil-->[[petroleum]] seems less important than previously thought (MacDonald, 1998b).<ref name="MMS 2006" />

Through [[taphonomy|taphonomic]] studies (death assemblages of shells) and interpretation of seep assemblage composition from cores, Powell et al. (1998) reported that, overall, seep communities were persistent over periods of 500–1,000 years and probably throughout the entire [[Pleistocene]]{{Dubious|date=April 2024}}. Some sites retained optimal [[habitat]] over [[geological time scale]]s. Powell reported evidence of mussel and clam communities persisting in the same sites for 500–4,000 years. Powell also found that both the composition of species and [[Trophic level|trophic]] tiering of hydrocarbon seep communities tend to be fairly constant across time, with temporal variations only in numerical abundance. He found few cases in which the community type changed (from mussel to clam communities, for example) or had disappeared completely. Faunal [[Ecological succession|succession]] was not observed. Surprisingly, when recovery occurred after a past destructive event, the same chemosynthetic species reoccupied a site. There was little evidence of catastrophic burial events, but two instances were found in mussel communities in Green Canyon Block 234. The most notable observation reported by Powell (1995) was the uniqueness of each chemosynthetic community site.<ref name="MMS 2006" />

Precipitation of [[authigenic]] carbonates and other geologic events will undoubtedly alter surface seepage patterns over periods of many years, although through direct observation, no changes in chemosynthetic fauna distribution or composition were observed at seven separate study sites (MacDonald et al., 1995). A slightly longer period (19 years) can be referenced in the case of Bush Hill, the first Central Gulf of Mexico community described ''[[in situ]]'' in 1986. No mass die-offs or large-scale shifts in faunal composition have been observed (with the exception of collections for scientific purposes) over the 19-year history of research at this site.<ref name="MMS 2006" />

All chemosynthetic communities are located in water depths beyond the effect of severe storms, including hurricanes, and there would have been no alteration of these communities caused from surface storms, including [[hurricane]]s.<ref name="MMS 2006" />

==== Biology ====

[[File:Bathymodiolus childressi.jpg|thumb|The mussel species ''[[Bathymodiolus childressi]]'' is the dominant species in the [[Mytilidae|mytilid]] type of cold seep communities in the Gulf of Mexico.]]

MacDonald et al. (1990) has described four general community types. These are communities dominated by [[Vestimentifera]]n tube worms (''[[Lamellibrachia]]'' c.f. ''[[Lamellibrachia barhami|barhami]]'' and ''[[Escarpia]]'' spp.), [[Mytilidae|mytilid]] mussels (Seep Mytilid Ia, Ib, and III, and others), [[Vesicomyidae|vesicomyid]] clams (''Vesicomya cordata'' and ''Calyptogena ponderosa''), and infaunal [[Lucinidae|lucinid]] or [[Thyasiridae|thyasirid]] clams (''[[Lucinoma]]'' sp. or ''[[Thyasira]]'' sp.). [[Bacterial mat]]s are present at all sites visited to date. These faunal groups tend to display distinctive characteristics in terms of how they aggregate, the size of aggregations, the geological and chemical properties of the habitats in which they occur, and, to some degree, the heterotrophic fauna that occur with them. Many of the species found at these cold seep communities in the Gulf of Mexico are new to science and remain [[undescribed species|undescribed]].<ref name="MMS 2006" />

Individual lamellibrachid [[Lamellibrachia|tube worms]], the longer of two taxa found at seeps, can reach lengths of 3&nbsp;m (10&nbsp;ft) and live hundreds of years (Fisher et al., 1997; Bergquist et al., 2000). [[Population growth rate|Growth rates]] determined from recovered marked tube worms have been variable, ranging from no growth of 13 individuals measured one year to a maximum growth of 9.6&nbsp;cm/yr (3.8 in/yr) in a ''[[Lamellibrachia]]'' individual (MacDonald, 2002). Average growth rate was 2.19&nbsp;cm/yr (0.86 in/yr) for the ''[[Escarpia]]''-like species and 2.92&nbsp;cm/yr (1.15 in/yr) for lamellibrachids. These are slower growth rates than those of their [[hydrothermal vent]] relatives, but ''Lamellibrachia'' individuals can reach lengths 2–3 times that of the largest known hydrothermal vent species.<ref name="MMS 2006" /> Individuals of ''Lamellibrachia'' sp. in excess of 3&nbsp;m (10&nbsp;ft) have been collected on several occasions, representing probable ages in excess of 400 years (Fisher, 1995). Vestimentiferan tube worm spawning is not seasonal, and recruitment is episodic.<ref name="MMS 2006" />

Tubeworms are either male or female. One recent discovery indicates that the spawning of female ''Lamellibrachia'' appears to have produced a unique association with the large bivalve ''Acesta bullisi'', which lives permanently attached to the anterior tube opening of the tubeworm, and feeds on the periodic egg release (Järnegren et al., 2005). This close association between the bivalves and tubeworms was discovered in 1984 (Boland, 1986) but not fully explained. Virtually all mature ''[[Acesta]]'' individuals are found on female rather than male tubeworms. This evidence and other experiments by Järnegren et al. (2005) seem to have solved this mystery.<ref name="MMS 2006" />

Growth rates for methanotrophic mussels at cold seep sites have been reported (Fisher, 1995).<ref name="MMS 2006" /> General growth rates were found to be relatively high. Adult mussel growth rates were similar to mussels from a littoral environment at similar temperatures. Fisher also found that juvenile mussels at hydrocarbon seeps initially grow rapidly, but the growth rate drops markedly in adults; they grow to reproductive size very quickly. Both individuals and communities appear to be very long-lived. These [[methane]]-dependent mussels have strict chemical requirements that tie them to areas of the most active seepage in the Gulf of Mexico. As a result of their rapid growth rates, mussel recolonization of a disturbed seep site could occur relatively rapidly. There is some evidence that mussels also have some requirement of a hard substrate and could increase in numbers if suitable substrate is increased on the seafloor (Fisher, 1995). Two associated species are always found associated with mussel beds—the gastropod ''[[Bathynerita naticoidea]]'' and a small [[Alvinocarididae|Alvinocarid]] shrimp—suggesting these endemic species have excellent [[Biological dispersal|dispersal abilities]] and can tolerate a wide range of conditions (MacDonald, 2002).<ref name="MMS 2006" />

Unlike mussel beds, chemosynthetic clam beds may persist as a visual surface phenomenon for an extended period without input of new living individuals because of low dissolution rates and low sedimentation rates. Most clam beds investigated by Powell (1995) were inactive. Living individuals were rarely encountered. Powell reported that over a 50-year timespan, local extinctions and recolonization should be gradual and exceedingly rare. Contrasting these inactive beds, the first community discovered in the Central Gulf of Mexico consisted of numerous actively-plowing clams. The images obtained of this community were used to develop length/frequency and live/dead ratios as well as spatial patterns (Rosman et al., 1987a).<ref name="MMS 2006" />

Extensive [[bacterial mat]]s of free-living [[bacteria]] are also evident at all hydrocarbon seep sites. These bacteria may compete with the major fauna for [[sulfide]] and [[methane]] energy sources and may also contribute substantially to overall production (MacDonald, 1998b). The white, nonpigmented mats were found to be an [[autotrophic]] [[Thiotrichaceae|sulfur bacteria]] ''[[Beggiatoa]]'' species, and the orange mats possessed an unidentified non-chemosynthetic metabolism (MacDonald, 1998b).<ref name="MMS 2006" />

Heterotrophic species at seep sites are a mixture of species unique to seeps (particularly [[molluscs]] and [[crustacean]] invertebrates) and those that are a normal component from the surrounding environment. Carney (1993) first reported a potential imbalance that could occur as a result of chronic disruption. Because of sporadic recruitment patterns, predators could gain an advantage, resulting in exterminations in local populations of mussel beds. It is clear that seep systems do interact with the background fauna, but conflicting evidence remains as to what degree outright predation on some specific community components such as tubeworms occurs (MacDonald, 2002). The more surprising results from this recent work is why background species do not utilize seep production more than seems to be evident. In fact, seep-associated consumers such as [[galatheid]] crabs and [[Neritidae|nerite]] gastropods had isotopic signatures, indicating that their diets were a mixture of seep and background production. At some sites, [[Endemism|endemic]] seep invertebrates that would have been expected to obtain much if not all their diet from seep production actually consumed as much as 50 percent of their diets from the background.<ref name="MMS 2006" />

=== In the Atlantic Ocean ===

[[File:Cold seeps of the Atlantic Ocean.png|thumb|Map of cold seeps in the Atlantic Equatorial Belt.<br />BR – [[Blake Ridge]] diapir<br />BT – Barbados trench<br />OR – Orenoque sectors<br />EP – El Pilar sector<br />NIG – Nigerian slope<br />GUI – {{Not a typo|Guiness}} area<br />REG – Regab pockmark.]]

Cold-seep communities in the western [[Atlantic Ocean]] have also been described from a few dives on mud volcanoes and [[diapir]]s between {{convert|1000|and(-)|5000|m|ft|abbr=on}} depth in the [[Barbados]] [[Accretionary wedge|accretionary prism]] area and from the [[Blake Ridge]] diapir off [[North Carolina]]. More recently, seep communities have been discovered in the eastern Atlantic, on a giant pockmark cluster in the [[Gulf of Guinea]] near the [[Congo River|Congo]] deep channel, and also on other pockmarks of the Congo margin, [[Gabon]] margin and [[Nigeria]] margin and in the [[Gulf of Cádiz]].<ref name="Olu 2010" />

The occurrence of chemosymbiotic [[Gulf of Cádiz#Biota|biota in the extensive mud volcano fields of the Gulf of Cádiz]] was first reported in 2003.<ref name="Pinheiro 2003">{{cite journal | last1 = Pinheiro | first1 = L. M. | last2 = Ivanov | first2 = M. K. | last3 = Sautkin | first3 = A. | last4 = Akhamanov | first4 = G. | last5 = Magalhães | first5 = V. H. | last6 = Volkonskaya | first6 = A. | last7 = Monteiro | first7 = J. H. | last8 = Somoza | first8 = L. | last9 = Gardner | first9 = J. | last10 = Hamouni | first10 = N. | last11 = Cunha | first11 = M. R. | year = 2003 | title = Mud volcanoes in the Gulf of Cadiz: results from the TTR-10 cruise | journal = [[Marine Geology (journal)|Marine Geology]] | volume = 195 | issue = 1–4| pages = 131–151 | doi = 10.1016/S0025-3227(02)00685-0 | bibcode = 2003MGeol.195..131P }}</ref> The chemosymbiotic [[bivalve]]s collected from the mud volcanoes of the Gulf of Cadiz were reviewed in 2011.<ref name="Oliver 2011" />

Cold seeps are also known from the Northern Atlantic Ocean,<ref name="Vanreusel 2010" /> even ranging into the Arctic Ocean, off Canada and [[Norway]].<ref name=Levin2005/>

<!-- === Biology === -->
Extensive faunal sampling has been conducted from {{convert|400|and(-)|3300|m|ft|abbr=on}} in the [[Atlantic Equatorial Belt]] from the Gulf of Mexico to the Gulf of Guinea including the Barbados accretionary prism, the Blake Ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin during [[Census of Marine Life]] [[Biogeography of Deep-Water Chemosynthetic Ecosystems|ChEss]] project. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic.<ref name="Olu 2010" />

The Atlantic Equatorial Belt seep megafauna community structure is influenced primarily by depth rather than by geographic distance. The bivalves [[Bathymodiolinae]] (within [[Mytilidae]]) species or complexes of species are the most widespread in the Atlantic. The ''[[Bathymodiolus boomerang]]'' complex is found at the Florida escarpment site, the Blake Ridge diapir, the Barbados prism, and the Regab site of Congo. The ''[[Bathymodiolus childressi]]'' complex is also widely distributed along the Atlantic Equatorial Belt from the Gulf of Mexico across to the Nigerian Margin, although not on the Regab or Blake Ridge sites. The commensal [[polynoid]] ''[[Branchipolynoe seepensis]]'' is known from the Gulf of Mexico, Gulf of Guinea, and Barbados. Other species with distributions extending from the eastern to western Atlantic are: gastropod <!--the gastropods ''[[Phymorhynchus cingulata]]'' DOUBTFUL GASTROPOD NAME REMOVED--><!--spelled in Olu 2010 as Phymorhynchus cingulatus Warén & Bouchet, 2009, but corerct name is either Phymorhynchus cingulata Warén & Bouchet, 2009 or  Phymorhynchus cingulatus (Dall, 1890)--> ''[[Cordesia provannoides]]'', the shrimp ''[[Alvinocaris muricola]]'', the galatheids ''[[Munidopsis geyeri]]'' and ''[[Munidopsis livida]],'' and probably the holothurid ''[[Chiridota hydrothermica]]''.<ref name="Olu 2010" />

There have been found cold seeps also in the [[Amazon River|Amazon]] deepsea fan. High-resolution seismic profiles near the shelf edge show evidence of near-surface slumps and faulting {{convert|20|-|50|m|ft|abbr=on}} in the subsurface and concentrations (about {{convert|500|m2|ft2|abbr=on|disp=or}}) of methane gas. Several studies (e.g., Amazon Shelf Study—[[AMASEDS]], [[LEPLAC]], [[REMAC]], GLORIA, [[Ocean Drilling Program]]) indicate that there is evidence for gas seepage on the slope off the Amazon fan based on the incidence of bottom-simulating reflections (BSRs), mud volcanoes, pockmarks, gas in sediments, and deeper hydrocarbon occurrences. The existence of methane at relatively shallow depths and extensive areas of gas hydrates have been mapped in this region. Also, [[Methane chimney|gas chimneys]] have been reported, and exploratory wells have discovered sub-commercial gas accumulations and pockmarks along fault planes. A sound geological and geophysical understanding of the [[Foz do Amazonas Basin]] is already available and used by the energy companies.<ref name="Miloslavich 2011">{{cite journal | last1 = Miloslavich | first1 = P. | last2 = Klein | first2 = E. | last3 = Díaz | first3 = J. M. | last4 = Hernández | first4 = C. E. | last5 = Bigatti | first5 = G.   | year = 2011 | title = Marine Biodiversity in the Atlantic and Pacific Coasts of South America: Knowledge and Gaps | journal = [[PLoS ONE]] | volume = 6 | issue = 1| page = e14631 | doi = 10.1371/journal.pone.0014631 | pmid = 21304960 | bibcode = 2011PLoSO...614631M | pmc = 3031619 | doi-access = free }}</ref>

Exploration of new areas, such as potential seep sites off of the east coast of the U.S. and the [[Laurentian Abyss|Laurentian]] fan where chemosynthetic communities are known deeper than {{convert|3500|m|ft|abbr=on}}, and shallower sites in the Gulf of Guinea are need to study in the future.<ref name="Olu 2010" />{{Clarify|date=April 2024}}

=== In the Mediterranean ===

The first biological evidence for reduced environments in the [[Mediterranean Sea]] was the presence of [[Lucinidae]] and [[Vesicomyidae]] [[bivalve shell]]s cored on the top of the Napoli [[mud volcano]] ({{coord|33|43|52|N|24|40|52|E|name=Napoli mud Volcano}}; "Napoli" is only a name of a seamount. It is located south of Crete), located at 1,900&nbsp;m deep on the [[Mediterranean Ridge]] in the [[subduction zone]] of the [[African Plate]]. This was followed by the description of a new Lucinidae bivalve species, ''[[Lucinoma kazani]]'', associated with bacterial [[endosymbiont]]s. In the southeastern Mediterranean, communities of [[polychaete]]s and bivalves were also found associated with cold seeps and carbonates near [[Egypt]] and the [[Gaza Strip]] at depths of 500–800&nbsp;m, but no living fauna was collected. The first [[in situ]] observations of extensive living chemosynthetic communities in the eastern Mediterranean Sea prompted cooperation between biologists, [[geochemist]]s, and geologists. During [[submersible]] dives, communities comprising large fields of small bivalves (dead and alive), large [[siboglinid]] tube worms, isolated or forming dense aggregations, large [[sponge]]s, and associated endemic fauna were observed in various cold seep habitats associated with carbonate crusts at 1,700–2,000 m depth. Two mud volcano fields were first explored, one along the Mediterranean Ridge, where most of them were partially (Napoli, Milano mud volcanoes) or totally (Urania, Maidstone mud volcanoes) affected by [[brine pool|brines]], and the other on the [[Anaximander mound]]s south of [[Turkey]]. The latter area includes the large Amsterdam mud volcano, which is affected by recent [[mudflow]]s, and the smaller Kazan or Kula mud volcanoes. [[Gas hydrate]]s have been sampled at the Amsterdam and Kazan mud volcanoes, and high methane levels have been recorded above the seafloor. Several provinces of the [[Nile]] deep-sea fan have been explored recently. These include the very active brine seepage named the [[Menes Caldera]] in the eastern province between 2,500&nbsp;m and 3,000&nbsp;m, the pockmarks in the central area along middle and lower slopes, and the mud volcanoes of the eastern province, as well as one in the central upper slope ([[North Alex]] area) at 500&nbsp;m depth.<ref name="Danovaro 2010" />

During these first exploratory dives, symbiont-bearing taxa that are similar to those observed on the Olimpi and Anaximander mud fields were sampled and identified. This similarity is not surprising, as most of these taxa were originally described from dredging in the Nile fan.<ref name="Danovaro 2010" /> Up to five species of bivalves harboring bacterial symbionts colonized these methane- and sulfide-rich environments. A new species of [[Siboglinidae]] polychaete, ''[[Lamellibrachia anaximandri]]'', the tubeworm colonizing cold seeps from the Mediterranean ridge to the Nile deep-sea fan, has just been described in 2010.<ref name="Danovaro 2010" /><ref>Southward E., Andersen A., Hourdez S. (submitted 2010). "''Lamellibrachia anaximandri'' n.sp., a new vestimentiferan tubeworm from the Mediterranean (Annelida)". ''[[Zoosystema]]''.</ref> Moreover, the study of symbioses revealed associations with chemoautotrophic [[Sulfur-reducing bacteria|bacteria, sulfur oxidizers]] in Vesicomyidae and Lucinidae bivalves and Siboglinidae tubeworms, and highlighted the exceptional diversity of bacteria living in symbiosis with small Mytilidae. The Mediterranean seeps appear to represent a rich habitat characterized by megafauna [[species richness]] (e.g., [[gastropod]]s) or the exceptional size of some species such as sponges (''[[Rhizaxinella pyrifera]]'') and crabs (''[[Chaceon mediterraneus]]''), compared with their background counterparts. This contrasts with the low macro- and mega-faunal abundance and diversity of the deep [[eastern Mediterranean]]. Seep communities in the Mediterranean that include endemic chemosynthetic species and associated fauna differ from the other known seep communities in the world at the species level but also by the absence of the large-size bivalve genera ''[[Calyptogena]]'' or ''[[Bathymodiolus]]''. The isolation of the Mediterranean seeps from the Atlantic Ocean after the [[Messinian crisis]] led to the development of unique communities, which are likely to differ in composition and structure from those in the Atlantic Ocean. Further expeditions involved quantitative sampling of habitats in different areas, from the Mediterranean Ridge to the eastern Nile deep-sea fan.<ref name="Danovaro 2010" /> Cold seeps discovered in the [[Sea of Marmara]] in 2008<ref>{{cite journal | last1 = Zitter | first1 = T. A. C | last2 = Henry | first2 = P. | last3 = Aloisi | first3 = G. | last4 = Delaygue | first4 = G. | last5 = Çagatay | first5 = M. N.   | year = 2008 | title = Cold seeps along the main Marmara Fault in the Sea of Marmara (Turkey) | url = https://archimer.ifremer.fr/doc/2008/publication-4065.pdf| journal = Deep-Sea Research Part I: Oceanographic Research Papers | volume = 55 | issue = 4| pages = 552–570 | doi = 10.1016/j.dsr.2008.01.002 | bibcode = 2008DSRI...55..552Z }}</ref> have also revealed chemosynthesis-based communities that showed a considerable similarity to the symbiont-bearing fauna of eastern Mediterranean cold seeps.<ref name="Danovaro 2010" />

=== In the Indian Ocean ===
In the [[Makran Trench]],  a subduction zone along the northeastern margin of the [[Gulf of Oman]] adjacent to the southwestern coast of [[Pakistan]] and the southeastern coast of [[Iran]], compression of an accretionary wedge has resulted in the formation of cold seeps and mud volcanoes.<ref>Fischer, D. ; Bohrmann, G. ; Zabel, M. ; Kasten, S. (April 2009): [https://ui.adsabs.harvard.edu/abs/2009EGUGA..11.6836F/abstract Geochemical zonation and characteristics of cold seeps along the Makran continental margin off Pakistan] EGU General Assembly Conference Abstracts. Retrieved 19 November 2020.</ref>

=== In the West Pacific ===

Native [[aluminium]] has been reported also in cold seeps in the northeastern [[continental slope]] of the [[South China Sea]] and Chen et al. (2011)<ref name="Chen 2011" /> have proposed a theory of its origin as resulting by [[Redox|reduction]] from [[tetrahydroxoaluminate]] Al(OH)<sub>4</sub><sup>−</sup> to metallic aluminium by [[bacteria]].<ref name="Chen 2011">{{cite journal | last1 = Chen | first1 = Z. | last2 = Huang | first2 = C.-Y. | last3 = Zhao | first3 = M. | last4 = Yan | first4 = W. | last5 = Chien | first5 = C.-W. | last6 = Chen | first6 = M. | last7 = Yang | first7 = H. | last8 = Machiyama | first8 = H. | last9 = Lin | first9 = S. | year = 2011 | title = Characteristics and possible origin of native aluminum in cold seep sediments from the northeastern South China Sea | journal = [[Journal of Asian Earth Sciences]] | volume = 40 | issue = 1| pages = 363–370 | doi = 10.1016/j.jseaes.2010.06.006 | bibcode = 2011JAESc..40..363C }}</ref>

==== Japan ====

{| class="wikitable" style="float:right"
|+ Chemosynthetic communities around Japan<ref name=Fujikura2008p450>{{cite book |last1=Fujikura |first1=Katsunori |title=Sensui chōsasen ga mita shinkai seibutsu : shinkai seibutsu kenkyū no genzai = Deep-sea life : biological observations using research submersibles |date=2008 |publisher=Tōkai Daigaku Shuppankai |location=Hadano-shi |isbn=978-4-486-01787-5 |edition=Dai 1-han |page=450}}</ref>
|-
|Cold seep
|
*[[Kuril–Kamchatka Trench]]-[[Japan Trench]]
*[[Sea of Japan]]
*[[Sagami Bay]]
*[[Suruga Bay]]
*[[Nankai Trough]]
*[[Kagoshima Bay]]
*[[Ryukyu Trench]]
|-
|Hydrothermal vent
|
*[[Izu Islands]]-[[Bonin Islands]]
*[[Mariana Islands]]
*[[Okinawa Trough]]
|-
|Whale fall
|
*Sagami Bay
*Off Cape Nomamisaki ([[East China Sea]])
*[[Tori-shima (Izu Islands)|Tori-shima]] seamount (Izu Islands)
|}

Deep sea communities around Japan are mainly researched by [[Japan Agency for Marine-Earth Science and Technology]] (JAMSTEC). [[DSV Shinkai 6500]], [[Kaikō ROV|Kaikō]], and other groups have discovered many sites.

Methane seep communities in [[Japan]] are distributed along [[Convergent boundary|plate convergence]] areas because of the accompanying [[Tectonics|tectonic]] activity. Many seeps have been found in the [[Japan Trench]], [[Nankai Trough]], [[Ryukyu Trench]], [[Sagami Bay]], [[Suruga Bay]], and the [[Sea of Japan]].<ref name="Fujikura 2010" />

Members of cold seep communities are similar to other regions in terms of family or genus, such as Polycheata, ''Lamellibrachia'', Bivalavia, Solemyidae, ''Bathymodiolus'' in Mytilidae, Thyasiridae, Calyptogena in Vesicomyidae, and so forth.<ref name=Fujikura2008p450 /> Many of the species in Japan's cold seeps are [[Endemism|endemic]].<ref name="Fujikura 2010" />

In Kagoshima Bay, there are methane gas seepages called "tagiri" (boiling). ''[[Lamellibrachia satsuma]]'' live around there. The depth of this site is only 80&nbsp;m, which is the shallowest point where Siboglinidae are known to live. ''L. satsuma'' may be kept in an aquarium for a long period at 1 atm. Two aquariums in Japan are keeping and displaying ''L. satsuma''. An observation method to introduce it into a transparent vinyl tube is being developed.<ref>{{cite web |year = 2010 |url = http://dl.ndl.go.jp/view/download/digidepo_1016353_po_16_01_05.pdf?contentNo=1 |title = Observation method of behaviour of vestimentifean tube-worm (Lamellibrachia satsuma) in its tube |first = Hiroshi |last = Miyake |author2 = Jun HASHIMOTO |author3 = Shinji TSUCHIDA |work = JAMSTEC深海研究. (16-I.生物学編) |format = PDF |access-date = 30 March 2012 }}</ref>

[[File:JAMSTEC's Shinkai 6500.jpg|thumb|[[DSV Shinkai 6500]]]]

DSV Shinkai 6500 discovered vesicomyid clam communities in the Southern [[Mariana Forearc]]. They depend on methane, which originates in [[serpentinite]]. Other chemosynthetic communities would depend on hydrocarbon origins organic substance in crust, but these communities depend on methane originating from inorganic substances from the mantle.<ref>{{cite web |date = 7 February 2012 |url = http://www.jamstec.go.jp/ifree/j/topics/20120207.html |title = マリアナ海溝、チャレンジャー海淵の近くにおいて、マントル物質から栄養を摂る生態系を発見～有人潜水調査船「しんかい6500」による成果～ |access-date = 29 March 2012 |archive-url = https://web.archive.org/web/20120923101116/http://www.jamstec.go.jp/ifree/j/topics/20120207.html |archive-date = 23 September 2012 |url-status = dead }}</ref><ref>{{cite journal |last = Ohara |first = Yasuhiko |author2 = Mark K. Reaganc |author3 = Katsunori Fujikurab |author4 = Hiromi Watanabeb |author5 = Katsuyoshi Michibayashid |author6 = Teruaki Ishiie |author7 = Robert J. Sternf |author8 = Ignacio Pujanaf |author9 = Fernando Martinezg |author10=Guillaume Girardc |author11 = Julia Ribeirof |author12 = Maryjo Brounceh |author13 = Naoaki Komorid |author14 = Masashi Kinod |date = 21 February 2012 |title = A serpentinite-hosted ecosystem in the Southern Mariana Forearc |doi = 10.1073/pnas.1112005109 |pmid = 22323611 |journal = Proceedings of the National Academy of Sciences of the United States of America |pages = 2831–2835 |volume=109|issue = 8 |pmc = 3286937 |bibcode = 2012PNAS..109.2831O |doi-access = free }}</ref>

In 2011, the area around the [[Japan Trench]] suffered from the [[2011 Tōhoku earthquake and tsunami|Tōhoku earthquake]]. There are cracks, methane seepages, and bacterial mats which were probably created by the earthquake.<ref>{{cite web |date = 15 August 2011 |url = http://www.jamstec.go.jp/j/about/press_release/20110815/ |title = 東北地方太平洋沖地震震源海域での有人潜水調査船「しんかい6500」による潜航調査で得られた画像について（速報） |publisher = 海洋研究開発機構 |access-date = 29 March 2012 }}</ref><ref>{{cite journal |last = Kawagucci |first = Shinsuke |author2 = Yukari T. Yoshida |author3 = Takuroh Noguchi |author4 = Makio C. Honda |author5 = Hiroshi Uchida |author6 = Hidenori Ishibashi |author7 = Fumiko Nakagawa |author8 = Urumu Tsunogai |author9 = Kei Okamura |author10=Yoshihiro Takaki |author11 = Takuro Nunoura |author12 = Junichi Miyazaki |author13 = Miho Hirai |author14 = Weiren Lin |author15 = Hiroshi Kitazato |author16 = Ken Takai |date = 3 January 2012 |title = Disturbance of deep-sea environments induced by the M9.0 Tohoku Earthquake |doi = 10.1038/srep00270 |pmid = 22355782 |pmc = 3280601 |journal = Scientific Reports|volume = 2 |pages = 270 |bibcode = 2012NatSR...2..270K }}</ref>

==== New Zealand ====
Off the mainland coast of [[New Zealand]], shelf-edge instability is enhanced in some locations by cold seeps of methane-rich fluids that likewise support chemosynthetic faunas and carbonate concretions.<ref name="Gordon 2010" /><ref>{{cite journal | last1 = Lewis | first1 = K. B. | last2 = Marshall | first2 = B. A. | year = 1996 | title = Seep faunas and other indicators of methane-rich dewatering on New Zealand convergent margins | journal = [[New Zealand Journal of Geology and Geophysics]] | volume = 39 | issue = 2| pages = 181–200 | doi = 10.1080/00288306.1996.9514704 | bibcode = 1996NZJGG..39..181L }}</ref><ref>{{cite journal | last1 = Orpin | first1 = A. R. | year = 1997 | title = Dolomite chimneys as possible evidence of coastal fluid expulsion, uppermost Otago continental slope, southern New Zealand | journal = Marine Geology | volume = 138 | issue = 1–2| pages = 51–67 | doi = 10.1016/S0025-3227(96)00101-6 | bibcode = 1997MGeol.138...51O }}</ref><ref name="Baco 2009">{{cite journal | last1 = Baco | first1 = A. R. | last2 = Rowden | first2 = A. A. | last3 = Levin | first3 = L. A. | last4 = Smith | first4 = C. R. | last5 = Bowden | first5 = D.   | year = 2009 | title = Initial characterization of cold seep faunal communities on the New Zealand margin | journal = Marine Geology | volume = 272 | issue = 1–4| pages = 251–259 | doi = 10.1016/j.margeo.2009.06.015 | bibcode = 2010MGeol.272..251B }}</ref> Dominant animals are tubeworms of the family [[Siboglinidae]] and bivalves of families [[Vesicomyidae]] and [[Mytilidae]] (''[[Bathymodiolus]]''). Many of its species appear to be endemic. Deep [[bottom trawling]] has [[Environmental effects of fishing|severely damaged]] cold seep communities, and those ecosystems are threatened. Cold seeps are found at depths down to 2,000&nbsp;m, and the topographic and chemical complexity of the habitats are not yet mapped{{When|date=April 2024}}. The scale of new-species discovery in these poorly-studied or unexplored ecosystems is likely to be high.<ref name="Baco 2009" /><ref name="Gordon 2010" />

=== In the East Pacific ===

[[File:ROV Ventana on Point Lobos.jpg|thumb|[[Monterey Bay Aquarium Research Institute]] has used [[remotely operated underwater vehicle]] ''Ventana'' in the research of [[Monterey Bay]] cold seeps.]]

In the deep sea, the [[COMARGE]] project has studied the biodiversity patterns along and across the [[Chile]]an margin through a complexity of ecosystems such as methane seeps and [[oxygen minimum zone]]s, reporting that such habitat [[heterogeneity]] may influence the biodiversity patterns of the local fauna.<ref name="Miloslavich 2011" /><ref>{{cite journal | last1 = Sellanes | first1 = J. | last2 = Neira | first2 = C. | last3 = Quiroga | first3 = E. | last4 = Teixido | first4 = N. | year = 2010 | title = Diversity patterns along and across the Chilean margin: a continental slope encompassing oxygen gradients and methane seep benthic habitats | journal = Marine Ecology | volume = 31 | issue = 1| pages = 111–124 | doi = 10.1111/j.1439-0485.2009.00332.x | bibcode = 2010MarEc..31..111S | hdl = 10261/56612 | hdl-access = free }}</ref><ref name="Sellanes 2008">{{cite journal | last1 = Sellanes | first1 = J. | last2 = Quiroga | first2 = E. | last3 = Neira | first3 = C. | year = 2008 | title = Megafauna community structure and trophic relationships at the recently discovered Concepción Methane Seep Area, Chile, ~36°S | journal = [[ICES Journal of Marine Science]] | volume = 65 | issue = 7| pages = 1102–1111 | doi = 10.1093/icesjms/fsn099 | doi-access = free }}</ref><ref>{{cite journal | last1 = Sellanes | first1 = J. | last2 = Quiroga | first2 = E. | last3 = Gallardo | first3 = V. A. | year = 2004 | title = First direct evidence of methane seepage and associated chemosynthetic communities in the bathyal zone off Chile | journal = [[Journal of the Marine Biological Association of the UK]] | volume = 84 | issue = 5| pages = 1065–1066 | doi = 10.1017/S0025315404010422h | bibcode = 2004JMBUK..84.1065S | s2cid = 85948533 }}</ref> Seep fauna include bivalves of families [[Lucinidae]], [[Thyasiridae]], [[Solemyidae]] (''[[Acharax]]'' sp.), and [[Vesicomyidae]] (''[[Calyptogena gallardoi]]'') and polychaetes (''[[Lamellibrachia]]'' sp. and two other polychaete species).<ref name="Sellanes 2008" /> Furthermore, in these soft reduced [[sediment]]s below the oxygen minimum zone off the Chilean margin, a diverse microbial community composed by a variety of large [[prokaryote]]s (mainly large multi-cellular filamentous "mega bacteria" of the genera ''[[Thioploca]]'' and ''[[Beggiatoa]]'', and of "macrobacteria" including a diversity of phenotypes), [[protist]]s (ciliates, flagellates, and foraminifers), as well as small metazoans (mostly nematodes and polychaetes) has been found.<ref name="Miloslavich 2011" /><ref name="Gallardo 2007">{{cite journal | last1 = Gallardo | first1 = V. A. | last2 = Espinoza | first2 = C. | editor4-first = Paul C. W | editor4-last = Davies | editor3-first = Alexei Y | editor3-last = Rozanov | editor2-first = Gilbert V | editor2-last = Levin | editor1-first = Richard B | editor1-last = Hoover | year = 2007 | title = Large multicellular filamentous bacteria under the oxygen minimum zone of the eastern South Pacific: a forgotten biosphere | journal = Proc. SPIE | volume = 6694 | pages = 66941H–11 | doi = 10.1117/12.782209 | series = Instruments, Methods, and Missions for Astrobiology X | bibcode = 2007SPIE.6694E..1HG | s2cid = 121829940 }}</ref> Gallardo et al. (2007)<ref name="Gallardo 2007" /> argue that the likely chemolithotrophic metabolism of most of these mega- and macrobacteria offer an alternative explanation to [[fossil]] findings, in particular to those from obvious non-littoral origins, suggesting that traditional hypotheses on the cyanobacterial origin of some fossils may have to be revised.<ref name="Miloslavich 2011" />

Cold seeps ([[Pockmark (geology)|pockmarks]]) are also known from depths of 130&nbsp;m in the [[Hecate Strait]], [[British Columbia]], Canada.<ref name="Barrie 2010">{{cite journal | last1 = Barrie | first1 = J. V. | last2 = Cook | first2 = S. | last3 = Conway | first3 = K. W. | year = 2010 | title = Cold seeps and benthic habitat on the Pacific margin of Canada | journal = [[Continental Shelf Research]] | volume = 31 | issue = 2 Supplement 1| pages = S85–S92 | doi = 10.1016/j.csr.2010.02.013 | bibcode = 2011CSR....31S..85V }}</ref> Unobvious fauna (also unobvious for cold seeps) have been found there with these dominating species: sea snail ''[[Fusitriton oregonensis]]'', anemone ''[[Metridium giganteum]]'', encrusting sponges, and bivalve ''[[Solemya reidi]]''.<ref name="Barrie 2010" />

Cold seeps with chemosynthetic communities along the USA Pacific coast occur in [[Monterey Canyon]], just off [[Monterey Bay]], California on a [[mud volcano]].<ref name="Lorenson 1999">Lorenson T. D., Kvenvolden K. A., Hostettler F. D.,  Rosenbauer R. J., Martin J. B. & Orange D. L. (1999). [http://walrus.wr.usgs.gov/monterey/hydrocarbons/sitemap.html "Hydrocarbons Associated with Fluid Venting Process in Monterey Bay, California"]. [[USGS]] [[Pacific Coastal & Marine Science Center]].</ref> There have been found, for example, ''[[Calyptogena]]'' clams ''[[Calyptogena kilmeri]]'' and ''[[Calyptogena pacifica]]''<ref>Goffredi S. K. & Barry J. P. (2000). "Factors regulating productivity in chemoautotrophic symbioses; with emphasis on ''Calyptogena kilmeri'' and ''Calyptogena pacifica''". Poster, [[Monterey Bay Aquarium Research Institute]]. accessed 3 February 2011. [http://www.mbari.org/benthic/sposter.pdf PDF].</ref> and [[foraminifera]]n ''[[Spiroplectammina biformis]]''.<ref>{{cite journal | last1 = Bernhard | first1 = J. M. | last2 = Buck | first2 = K. R. | last3 = Barry | first3 = J. P. | year = 2001 | title = Monterey Bay cold-seep biota: Assemblages, abundance, and ultrastructure of living foraminifera | journal = Deep-Sea Research Part I: Oceanographic Research Papers | volume = 48 | issue = 10| pages = 2233–2249 | doi = 10.1016/S0967-0637(01)00017-6 | bibcode = 2001DSRI...48.2233B }}</ref>
* [http://www.mbari.org/benthic/coldseeploc.htm map of cold seeps in the Monterey Bay]
Additionally, seeps have been discovered offshore southern California in the inner California Borderlands along several fault systems including the San Clemente fault,<ref>{{Cite journal |title = A deep-sea hydrothermal site on a strike-slip fault |date = 1979 |journal = Nature |volume = 281 |issue = 5732 |pages = 531–534 |doi = 10.1038/281531a0 |last = Lonsdale, P. |bibcode =1979Natur.281..531L|s2cid = 4310057 }}</ref> San Pedro fault,<ref>{{Cite journal |title = Association among active seafloor deformation, mound formation, and gas hydrate growth and accumulation within the seafloor of the Santa Monica Basin, offshore California |author1 = Paull, C. K. |author2 = W. R. Normark |author3 = W. Ussler III |author4 = D. W. Caress |author5 = R. Keaten |name-list-style=amp|date = 2008 |journal = Marine Geology |volume = 250 |issue = 3–4 |pages = 258–275 |doi = 10.1016/j.margeo.2008.01.011 |bibcode = 2008MGeol.250..258P }}</ref> and [[San Diego Trough Fault Zone|San Diego Trough fault]].<ref name=":0">{{Cite journal |url =https://authors.library.caltech.edu/58911/1/grl52960.pdf  |title = Transpressional segment boundaries in strike-slip fault systems offshore southern California: Implications for fluid expulsion and cold-seep habitats |last1 = Maloney |first1 = J.M. |first2 = B.M. |last2 = Grupe |first3 = A.L. |last3 = Pasulka |first4 = K.S. |last4 = Dawson |first5 = D.H. |last5 = Case |first6 = C.A. |last6 = Frieder |first7 = L.A. |last7 = Levin |first8 = N.W. |last8 = Driscoll |date = 2015 |journal = Geophysical Research Letters |volume = 42 |issue = 10 |pages = 4080–4088 |doi = 10.1002/2015GL063778 |bibcode = 2015GeoRL..42.4080M |doi-access = free }}</ref> Fluid flow at the seeps along the San Pedro and San Diego Trough faults appears controlled by localized restraining bends in the faults.<ref name=":0" />

=== In the Antarctic ===

The first cold seep from the [[Southern Ocean]] was reported in 2005.<ref name="Domack 2005" /> The relatively few investigations to the Antarctic deep sea have shown the presence of deep-water habitats, including [[hydrothermal vent]]s, cold seeps, and [[mud volcano]]es.<ref name="Griffiths 2010" /> Other than the [[Antarctic Benthic Deep-Sea Biodiversity Project]] (ANDEEP) cruises, little work has been done in the deep sea.<ref name="Griffiths 2010" /> There are more species waiting to be described.<ref name="Griffiths 2010">{{cite journal | last1 = Griffiths | first1 = H. J. | year = 2010 | title = Antarctic Marine Biodiversity – What Do We Know About the Distribution of Life in the Southern Ocean? | journal = [[PLoS ONE]] | volume = 5 | issue = 8| page = e11683 | doi = 10.1371/journal.pone.0011683 | pmid = 20689841 | pmc = 2914006 | bibcode = 2010PLoSO...511683G | doi-access = free }}</ref>