{{Short description|Ecological region at the lowest level of a body of water}}
The '''benthic zone''', {{etymology|grc|''{{wikt-lang|grc|βένθος}}'' ({{grc-transl|βένθος}})|the depths of the ocean}},<ref>{{wiktionary-inline|benthos}}</ref> is the ecological region at the lowest level of a [[body of water]], such as a [[stream]], [[river]], [[lake]], or [[ocean]], including the sediment surface and some sub-surface layers.
Organisms living in this zone are called [[#Benthos|''benthos'']], or more informally ''bottom dwellers''. They include [[microorganisms]] such as [[bacteria]] and [[Fungus|fungi]],<ref>{{Cite book|title=Limnology: Lake and River Ecosystems, 3rd edn.|last=Wetzel|first=Robert G.|publisher=Academic Press, San Diego|year=2001|pages=635–637}}</ref><ref>{{Cite book|title=Bacterial Biogeochemistry: The Ecophysiology of Mineral Cycling, 3rd edn.|last1=Fenchel|first1=T.|last2=King|first2=G.|last3=Blackburn|first3=T. H.|publisher=Academic Press, London|year=2012|pages=121–122}}</ref> as well as larger [[invertebrates]] such as [[crustacean]]s and [[polychaete]]s.<ref>{{cite web|url=http://www.baybenthos.versar.com/benthos.htm |title=What Are Benthos? |publisher=[[Versar|Baybenthos.versar.com]] |date=2006-01-23 |access-date=2013-11-24}}</ref> Benthos generally live in close relationship with the substrate and many are permanently attached to the bottom. The [[benthic boundary layer]], which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include [[sand]] bottoms, rocky outcrops, [[coral]], and [[bay mud]].
==Physical description==
===Oceans=== The benthic region of the ocean begins at the shore line ([[intertidal zone|intertidal]] or [[littoral zone]]) and extends downward along the surface of the [[continental shelf]] out to sea. Thus, the region incorporates a great variety of physical conditions differing in depth, light penetration and pressure.<ref>{{cite book |year=2022|last1=Walag |first1=Angelo |editor1-last=Godson |editor1-first=Prince |title=Ecology and Biodiversity of Benthos |publisher=[[Elsevier]] |location=Amsterdam, Netherlands |isbn=978-0-12-821161-8 |page=1 |chapter=Understanding the world of Benthos: an introduction to Benthology|display-editors=etal}}</ref> The benthic zone includes all areas of bottom that are below the water.
The continental shelf is a benthic region of a tectonic plate that extends away from the shoreline of a land mass. At the continental shelf edge, usually about {{convert|200|m}} deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the deep sea floor. The generally flat part of the deep-sea floor is called the [[abyssal plain]] and is usually about {{convert|4000|m}} deep. The ocean floor is not all flat but has [[Mid-ocean ridge|submarine ridges]], [[seamount]]s and deep [[ocean trench]]es known as the [[hadal zone]].<ref>{{cite book |last1=Nichols |first1=C. Reid |last2=Williams |first2=Robert G. |title=Encyclopedia of marine science |date=2009 |publisher=[[Infobase Publishing|Infobase]] |location=New York |isbn=978-1-4381-1881-9 |chapter=hadal zone}}</ref> For comparison, the [[pelagic zone]] is the ecological region above the benthos, comprising the [[water column]] up to the surface. The benthos of the deep ocean includes the bottom levels of the oceanic [[abyssal zone]].<ref>Nichols, Williams (2009): "abyssal zone"</ref>
The deeper areas of the oceans beyond the penetration of daylight are the [[aphotic zone]]. Generally, this region is inhabited by life forms that tolerate cool [[temperature]]s and low [[oxygen]] levels, depending on the depth of the water.<ref>Nichols, Williams (2009): "aphotic zone"</ref>
===Lakes=== As with oceans, the ''benthic zone'' is the floor of the lake, which may be covered by accumulated sunken [[organic matter]] and mineral sediments, and the organisms that live in and on it. The ''littoral zone'' is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The ''pelagic zone'' is the water between the surface and the bottom. the [[photic zone]] is the water column down to the depth to which no light penetrates. This depth varies depending on clarity of the water.<ref>{{cite book |last1=Silk |first1=Nicole |last2=Ciruna |first2=Kristine |title=A practitioner's guide to freshwater biodiversity conservation |date=2005 |publisher=[[Island Press]] |location=Washington, DC |isbn=978-1-59726-043-5}}</ref>
==Benthos== [[File:Neuston, Plankton, Nekton, Benthos.jpg|thumb|upright=1.3| {{center|Benthos (organisms that live at the ocean floor) can be contrasted with [[neuston]] (organisms that live at the ocean surface) [[plankton]] (organisms that drift with water currents) and [[nekton]] (organisms that can swim against water currents)}}]] {{benthos sidebar}}
'''Benthos''' is the [[community (ecology)|community]] of [[organism]]s that live in the benthic zone, that is, on, in, or near the bottom of a [[stream]], [[river]], [[lake]], or [[ocean]].<ref name="caml">[http://www.caml.aq/benthos/index.html Benthos] from the Census of Antarctic Marine Life website</ref> This community lives in or near marine or freshwater [[depositional environment|sedimentary environments]], from [[tidal pool]]s along the [[intertidal zone|foreshore]], out to the [[continental shelf]], and then down to the [[abyssal zone|abyssal depths]].
The term ''benthos'', coined by [[Haeckel]] in 1891,<ref>{{lang|de|Haeckel, E. 1891. Plankton-Studien. Jenaische Zeitschrift für Naturwissenschaft 25 / (Neue Folge)}} 18: 232–336. [https://www.biodiversitylibrary.org/page/11963729 BHL].</ref> comes from the [[English words of Greek origin|Greek]] noun {{lang|grc|βένθος}} 'depth of the ocean'.<ref name="caml" /><ref>{{LSJ|be/nqos|βένθος|ref}}.</ref> Additionally to oceans, ''benthos'' is also used in [[freshwater Biology|freshwater biology]] to refer to organisms at the bottom of freshwater [[body of water|bodies of water]], such as streams, rivers, and lakes.<ref>{{Cite web |url=http://www.benthos.org/AboutNABS/Whatisbenthos.htm |title=North American Benthological Society website |access-date=2008-08-16 |archive-url=https://web.archive.org/web/20080705155246/http://www.benthos.org/AboutNABS/Whatisbenthos.htm |archive-date=2008-07-05 |url-status=dead }}</ref> There is also a redundant, occasionally used synonym, ''benthon''.<ref>Nehring, S. & Albrecht, U. (1997). ''Benthos und das redundant Benton: Neologismen in der deutschsprachigen Limnologie''. ''Lauterbornia'' 31: 17-30, [http://www.zobodat.at/pdf/Lauterbornia_1997_31_0017-0030.pdf].</ref> Benthos is also referred to more loosely and informally as ''bottom dwellers'' or ''[[bottom feeder]]s''.
Light is an important energy source for shallow benthic systems. However, because light is [[Electromagnetic absorption by water|absorbed]] before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This [[detritus|dead and decaying matter]] sustains the benthic [[food chain]]; most organisms in the benthic zone are [[scavengers]] or [[detritivores]].
Many organisms adapted to deep-water pressure cannot survive in the upper parts of the [[water column]]. The pressure difference can be significant (approximately one [[atmosphere (unit)|atmosphere]] for every 10 metres of water depth).<ref name="NOAA">{{Cite web|url=https://oceanservice.noaa.gov/facts/pressure.html|title=How does pressure change with ocean depth?|first=National Oceanic and Atmospheric Administration|last=US Department of Commerce|website=oceanservice.NOAA.gov}}</ref>
Compared to the relatively featureless [[pelagic zone]], the benthic zone offers physically diverse habitats. There is a huge range in how much light and warmth is available, and in the depth of water or extent of [[intertidal]] immersion. The seafloor varies widely in the types of [[Marine sediment|sediment]] it offers. [[Burrow|Burrowing animals]] can find protection and food in soft, loose sediments such as [[mud]], [[clay]] and [[sand]]. [[Sessility (motility)|Sessile species]] such as [[oyster]]s and [[barnacle]]s can attach themselves securely to hard, rocky substrates. As adults they can remain at the same site, shaping depressions and crevices where mobile animals find refuge. This greater diversity in benthic habitats has resulted in a higher diversity of benthic species. The number of benthic animal species exceeds one million. This far exceeds the number of pelagic animal species (about 5000 larger zooplankton species, 22,000 pelagic fish species and 110 marine mammal species).<ref name= Lalli1997>{{cite book | last1=Lalli | first1=Carol M. | last2=Parsons | first2=Timothy R. | title=Biological Oceanography: An Introduction | chapter=Benthos | url=https://books.google.com/books?id=c6J5hlcjFaAC&q=%22Biological+Oceanography%3A+An+Introduction%22| publisher=Elsevier | year=1997 | pages=177–195 | doi=10.1016/b978-075063384-0/50063-3| isbn=9780750633840 }}</ref>
Benthos are the organisms that live in the benthic zone, and are different from those elsewhere in the [[water column]]; even within the benthic zone variations in such factors as substrate, light penetration, temperature and salinity give rise to distinct differences, delineated vertically, in the groups of organisms supported.<ref name=aw2>Walag (2022) p.2</ref> Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column:{{cn|date=December 2025}}{{clarify|is it actually the pressure or is it other differences that they are not adapted for?|date=December 2025}} the pressure difference can be very significant (approximately one [[atmosphere (unit)|atmosphere]] for each 10 meters of water depth). Many have adapted to live on the substrate (bottom) or within the upper layers of the bottom. In their habitats they can be considered as dominant creatures, but they are often a source of prey for [[Carcharhinidae]] such as the [[lemon shark]].<ref>{{cite book|last=Bright|first=Michael|title=The private life of sharks: the truth behind the myth|year=2000|publisher=Stackpole Books|location=Mechanicsburg, Pennsylvania |isbn=0-8117-2875-7}}</ref>
Because light does not penetrate very deep into ocean-water, the energy source for the benthic ecosystem is often [[marine snow]]. Marine snow is organic matter from higher up in the water column that drifts down to the depths.<ref>{{cite book |last1=Matthiessen |first1=Berte |editor1-last=Salomon |editor1-first=Markus |title=Handbook on Marine Environment Protection |date=2018 |publisher=[[Springer Science+Business Media|Springer]] |display-editors=etal|location=Berlin |isbn=978-3-319-60154-0 |page=53 |chapter=Ecological Organization of the Ocean}}</ref> This [[detritus|dead and decaying matter]] sustains the benthic [[food chain]]; most organisms in the benthic zone are [[scavenger]]s or [[detritivore]]s. Some [[microorganism]]s use [[chemosynthesis]] to produce [[Biomass (ecology)|biomass]].
Benthic organisms can be divided into two categories based on whether they make their home on the ocean floor or a few centimeters into the ocean floor. Those living on the surface of the ocean floor are known as [[epifauna]].<ref>{{cite web|url=http://www.merriam-webster.com/dictionary/epifaunal |title=Epifaunal - Definition and More from the Free Merriam-Webster Dictionary |publisher=Merriam-webster.com |date=2012-08-31 |access-date=2013-11-24}}</ref> Those who live burrowed into the ocean floor are known as [[infauna]].<ref name=aw2/> Extremophiles, including [[piezophile]]s, which thrive in high pressures, may also live there.
===By taxon===
===By size===
====Macrobenthos==== [[File:Benthic GLERL 1.jpg|[[Photomicrograph]] of typical benthic animals, including (from top to bottom) [[amphipods]], a [[polychaete]] worm, a [[Sea snail|snail]], and a [[Chironomidae|chironomous]] midge larva|thumb]] {{main|Macrobenthos}}
Macrobenthos, prefix {{etymology|grc|makrós|long}}, comprises the larger, visible to the naked eye, benthic organisms greater than about 1 mm in size. In shallow waters, [[seagrass meadow]]s, coral reefs and kelp forests provide particularly rich habitats for macrobenthos. Some examples are [[polychaete|polychaete worms]], [[bivalve]]s, [[echinoderm]]s, [[sea anemone]]s, [[coral]]s, [[sponge]]s, [[Ascidian|sea squirts]], [[turbellarian]]s and larger [[crustacean]]s such as [[crab]]s, [[lobster]]s and [[cumacean]]s.<ref>{{cite book | last=Sokolova | first=M. N. | title=Feeding and trophic structure of the deep-sea macrobenthos | publisher=Science Publishers | publication-place=Enfield, NH | year=2000 | isbn=978-1-57808-090-8 | oclc=46724477}}</ref>
<gallery mode="packed" heights="135px" style="float:left;"> File:Floridian seagrass bed.jpg| [[Seagrass]] File:Nerr0878.jpg| [[Echinoderm]]s File:Ascidian (Rhopalaea Crassa) (4 cm).png| [[Sea squirt]]s </gallery> {{clear}}
====Meiobenthos==== {{main|Meiobenthos}} [[Meiobenthos]], prefix {{etymology|grc|meîon|less}}, comprises tiny benthic organisms that are less than about 1 mm but greater than about 0.1 mm in size. Some examples are [[nematode]]s, [[foraminiferan]]s, [[tardigrade]]s, [[gastrotrich]]es and smaller [[crustacean]]s such as [[copepod]]s and [[ostracode]]s.
<gallery mode="packed" heights="145px" style="float:left;"> File:Ammonia tepida.jpg| [[Foraminiferan]] File:Gastrotrich.jpg| [[Gastrotrich]] File:copepodkils.jpg| [[Copepod]] File:SEM image of Milnesium tardigradum in active state - journal.pone.0045682.g001-2.png| [[Tardigrade]] (water bear) </gallery> {{clear}}
====Microbenthos==== {{see also|Seabed#Sediments|Marine sediment#Microbenthos|bioturbation|bioirrigation}}
Microbenthos, prefix from the Greek ''mikrós'' 'small', comprises microscopic benthic organisms that are less than about 0.1 mm in size. Some examples are [[bacteria]], [[diatoms]], [[ciliate]]s, [[amoeba]], [[flagellate]]s.
<gallery mode="packed" heights="150px" style="float:left;"> File:Diatoms through the microscope.jpg| [[Diatoms]] File:Paramecium bursaria.jpg| [[Ciliate]] File:CSIRO ScienceImage 7609 SEM dinoflagellate.jpg| [[Dinoflagellate]]s </gallery> {{clear}}
Marine microbenthos are microorganisms that live in the benthic zone of the ocean – that is, near or on the seafloor, or within or on surface seafloor sediments. Microbenthos are found everywhere on or about the seafloor of continental shelves, as well as in deeper waters, with greater diversity in or on seafloor sediments. In [[photic zone]]s benthic diatoms dominate as photosynthetic organisms. In [[intertidal zone]]s changing [[tide]]s strongly control opportunities for microbenthos.
<gallery mode="packed" heights="180px" style="float:left;"> File:Elphidium-incertum hg.jpg|''[[Elphidium]]'' a widespread abundant genus of benthic forams File:FMIB 50025 Textilaria.jpeg|''[[Heterohelix]]'', an extinct genus of benthic forams </gallery>
<gallery mode="packed" heights="150px" style="float:right;" caption="Marine microanimals"> File:Gastrotrich.jpg|[[Dark field microscopy|Darkfield photo]] of a [[gastrotrich]], 0.06-3.0 mm long, a worm-like animal living between sediment particles File:Pliciloricus enigmatus.jpg|Armoured ''[[Pliciloricus enigmaticus]]'', about 0.2 mm long, live in spaces between marine gravel </gallery>
{{clear}}
Both foraminifera and diatoms have [[planktonic]] and [[benthic]] forms, that is, they can drift in the [[water column]] or live on [[Marine sediment|sediment]] at the bottom of the ocean. Regardless of form, their shells sink to the seafloor after they die. These shells are widely used as [[climate proxy|climate proxies]]. The chemical composition of the shells are a consequence of the chemical composition of the ocean at the time the shells were formed. Past water temperatures can be also be inferred from the ratios of stable [[oxygen isotope]]s in the shells, since lighter isotopes evaporate more readily in warmer water leaving the heavier isotopes in the shells. Information about past climates can be inferred further from the abundance of forams and diatoms, since they tend to be more abundant in warm water.<ref>Bruckner, Monica (2020) [https://serc.carleton.edu/microbelife/topics/proxies/index.html"Paleoclimatology: How Can We Infer Past Climates?"] ''[[Science Education Resource Center|SERC]]'', Carleton College. Modified 23 July 2020. Retrieved 10 September 2020.</ref>[[File:Benthic Diatom.jpg|thumb|{{center|Benthic diatom}}]]The sudden [[Cretaceous–Paleogene extinction event|extinction event]] which killed the dinosaurs 66 million years ago also rendered extinct three-quarters of all other animal and plant species. However, deep-sea benthic forams flourished in the aftermath. In 2020 it was reported that researchers have examined the chemical composition of thousands of samples of these benthic forams and used their findings to build the most detailed climate record of Earth ever.<ref>[https://www.livescience.com/oldest-climate-record-ever-cenozoic-era.html Earth barreling toward 'Hothouse' state not seen in 50 million years, epic new climate record shows] ''LiveScience'', 10 September 2020.</ref><ref name="Westerhold2020">{{cite journal | url=https://www.science.org/doi/10.1126/science.aba6853 | doi=10.1126/science.aba6853 | title=An astronomically dated record of Earth's climate and its predictability over the last 66 million years | year=2020 | last1=Westerhold | first1=Thomas | last2=Marwan | first2=Norbert | last3=Drury | first3=Anna Joy | last4=Liebrand | first4=Diederik | last5=Agnini | first5=Claudia | last6=Anagnostou | first6=Eleni | last7=Barnet | first7=James S. K. | last8=Bohaty | first8=Steven M. | last9=De Vleeschouwer | first9=David | last10=Florindo | first10=Fabio | last11=Frederichs | first11=Thomas | last12=Hodell | first12=David A. | last13=Holbourn | first13=Ann E. | last14=Kroon | first14=Dick | last15=Lauretano | first15=Vittoria | last16=Littler | first16=Kate | last17=Lourens | first17=Lucas J. | last18=Lyle | first18=Mitchell | last19=Pälike | first19=Heiko | last20=Röhl | first20=Ursula | last21=Tian | first21=Jun | last22=Wilkens | first22=Roy H. | last23=Wilson | first23=Paul A. | last24=Zachos | first24=James C. | journal=Science | volume=369 | issue=6509 | pages=1383–1387 | pmid=32913105 | bibcode=2020Sci...369.1383W | hdl=11577/3351324 | s2cid=221593388 | hdl-access=free }}</ref>
Some [[endolith]]s have extremely long lives. In 2013 researchers reported evidence of endoliths in the ocean floor, perhaps millions of years old, with a generation time of 10,000 years.<ref>Bob Yirka [http://phys.org/news/2013-08-soil-beneath-ocean-harbor-bacteria.html 29 Aug 2013]</ref> These are slowly metabolizing and not in a dormant state. Some [[Actinomycetota]] found in [[Siberia]] are estimated to be half a million years old.<ref>[https://www.theguardian.com/theobserver/2010/may/02/rachel-sussman-oldest-plants Sussman: Oldest Plants], [[The Guardian]], 2 May 2010</ref><ref>{{Cite web |url=https://www.itsokaytobesmart.com/post/91481365622/siberian-actinobacteria-oldest-living-thing |title=It's Okay to be Smart • the oldest living thing in the world: These |access-date=2018-07-13 |archive-url=https://web.archive.org/web/20180713074804/https://www.itsokaytobesmart.com/post/91481365622/siberian-actinobacteria-oldest-living-thing |archive-date=2018-07-13 |url-status=dead }}</ref><ref>{{Cite journal|title=Ancient bacteria show evidence of DNA repair|first1=Eske |last1=Willerslev|first2=Duane |last2=Froese|first3=David |last3=Gilichinsky|first4=Regin |last4=Rønn|first5=Michael|last5=Bunce|first6=Maria T.|last6=Zuber |first7=M. Thomas P.|last7=Gilbert |first8=Tina |last8=Brand |first9=Kasper |last9=Munch |first10=Rasmus|last10=Nielsen |first11=Mikhail|last11=Mastepanov|first12=Torben R. |last12=Christensen |first13=Martin B.|last13=Hebsgaard |first14=Sarah Stewart|last14=Johnson |date=4 September 2007|journal=Proceedings of the National Academy of Sciences|volume=104|issue=36|pages=14401–14405|doi=10.1073/pnas.0706787104 |pmid=17728401|pmc=1958816 |bibcode=2007PNAS..10414401J|doi-access=free }}</ref>
{{clear}}
===By trophic level=== [[File:Libr0409.jpg|thumb|upright=1.1| {{center|'''Example zoobenthos'''<br />''A variety of marine worms''<br />Plate from ''Das Meer''<br />by M. J. Schleiden (1804–1881)}}]]
====Zoobenthos==== Zoobenthos, prefix {{etymology|grc|zôion|animal}}, animals belonging to the benthos. Examples include [[Polychaete|polychaete worms]], starfish and anemones.
====Phytobenthos==== [[Phytobenthos]], prefix {{etymology|grc|phutón|plant}}, plants belonging to the benthos, mainly benthic [[diatom]]s and [[macroalgae]] ([[seaweed]]).
===By location=== ====Endobenthos==== Endobenthos (or endobenthic), prefix {{etymology|grc|éndon|inner, internal}}, lives buried, or burrowing in the sediment, often in the [[Oxygenation (environmental)|oxygenated]] top layer, e.g., a [[sea pen]] or a [[sand dollar]].
====Epibenthos==== Epibenthos (or epibenthic), prefix {{etymology|grc|epí|on top of}}, lives on top of the sediments, e.g., [[sea cucumber]] or a sea snail.
====Hyperbenthos==== Hyperbenthos (or hyperbenthic), prefix {{etymology|grc|hupér|over}}, lives just above the sediment, e.g., a [[rock cod]].
===By habitat=== {{ocean habitat topics}}
Modern [[seafloor mapping]] technologies have revealed linkages between seafloor geomorphology and benthic habitats, in which suites of benthic communities are associated with specific geomorphic settings.<ref>Harris, P. T.; Baker, E. K. 2012. "[[GEOHAB]] Atlas of seafloor geomorphic features and benthic habitats – synthesis and lessons learned", in: Harris, P. T.; Baker, E. K. (eds.), ''Seafloor Geomorphology as Benthic Habitat: GeoHab Atlas of seafloor geomorphic features and benthic habitats''. Elsevier, Amsterdam, pp. 871–890.</ref> Examples include [[cold-water coral]] communities associated with seamounts and submarine canyons, [[kelp forest]]s associated with inner shelf rocky reefs and [[rockfish]] associated with rocky escarpments on continental slopes.<ref>Harris, P. T.; Baker, E. K.; 2012. ''Seafloor Geomorphology as Benthic Habitat: GeoHab Atlas of seafloor geomorphic features and benthic habitats''. Elsevier, Amsterdam, p. 947.</ref> In [[ocean]]ic environments, [[habitats]] can also be zoned by depth. From the shallowest to the deepest are: the [[epipelagic]] (less than 200 meters), the [[mesopelagic]] (200–1,000 meters), the [[bathyal]] (1,000–4,000 meters), the [[abyssal]] (4,000–6,000 meters) and the deepest, the [[hadal]] (below 6,000 meters).<ref>{{Cite journal |date=2012 |title=Coastal and Marine Ecological Classification Standard (CMECS) |url=https://repository.library.noaa.gov/view/noaa/27552 |language=en}}</ref>
[[File:Pteropurpura trialata is laying the eggs 1.jpg|thumb|upright=1.2|alt=Photo of dozens of palm-tree shaped seaweed plants exposed to the air|{{center|Low tide zone in a tide pool}}]]
Human impacts have occurred at all ocean depths, but are most significant on shallow continental shelf and slope habitats.<ref>Harris, P. T., 2012. "Anthropogenic threats to benthic habitats", in: Harris, P. T.; Baker, E. K. (eds.), ''Seafloor Geomorphology as Benthic Habitat: GeoHab Atlas of seafloor geomorphic features and benthic habitats''. Elsevier, Amsterdam, pp. 39–60.</ref> Many benthic organisms have retained their historic evolutionary characteristics. Some organisms are [[Deep-sea gigantism|significantly larger]] than their relatives living in shallower zones, largely because of higher oxygen concentration in deep water.<ref>[http://www.naturalsciences.be/active/sciencenews/archive2005/polarregions/page3/document_view Royal Belgian Institute of Natural Sciences, news item March 2005] {{webarchive |url=https://web.archive.org/web/20110928104251/http://www.naturalsciences.be/active/sciencenews/archive2005/polarregions/page3/document_view |date=September 28, 2011 }}</ref>
It is not easy to map or observe these organisms and their habitats, and most modern observations are made using [[remotely operated underwater vehicle]]s (ROVs), and rarely crewed [[submersible]]s.<ref>{{cite book |last1=Clark |first1=Malcolm |title=Biological sampling in the deep sea |date=2016 |publisher=[[Wiley (publisher)|Wiley]] |location=Hoboken, New Jersey |isbn=978-1-118-33255-9 |page=30|display-authors=etal}}</ref><ref>{{cite web |last1=Tillin |first1=H. M. |title=Marine Monitoring Platform Guidelines: Remotely Operated Vehicles for use in marine benthic monitoring |url=https://data.jncc.gov.uk/data/4abdba96-8ade-468d-8f80-c23a6ad87dc5/JNCC-MMPG-001-FINAL-WEB.pdf |publisher=[[Joint Nature Conservation Committee]] |access-date=15 June 2022 |location=Peterborough, UK |page=1|display-authors=etal}}</ref>
[[Tide pool]]s provide somewhat demanding benthic homes for organisms such as [[sea stars]], [[mussel]]s and [[clam]]s. Inhabitants deal with a frequently changing [[Biophysical environment|environment]]: fluctuations in water [[temperature]], salinity, and [[oxygen]] content. Hazards include [[Wind wave|waves]], strong [[Ocean current|current]]s, exposure to midday sun and predators. [[Wave]]s can dislodge mussels and draw them out to sea. [[Gull]]s pick up and drop [[sea urchin]]s to break them open. Sea stars prey on mussels and are eaten by gulls themselves. [[American Black Bear|Black bear]]s are known to sometimes feast on intertidal creatures at low tide.<ref name="Botanical Beach">{{cite news |title = Botanical Beach Tide Pools |publisher = [[BC Parks|British Columbia Parks]] |date = September 5, 2008 |url = http://www.juandefucamarinetrail.com/botanical_beach.html |archive-url = https://web.archive.org/web/20080724193444/http://www.juandefucamarinetrail.com/botanical_beach.html |archive-date = 2008-07-24 }}</ref> Although tide pool organisms must avoid getting washed away into the [[ocean]], drying up in the sun, or being eaten, they depend on the tide pool's constant changes for food.<ref name="NPCA Tide pools">{{cite news |title=NPCA Tide pools |publisher=[[National Parks Conservation Association|NPCA]] |date=September 5, 2008 |url=http://www.npca.org/marine_and_coastal/beaches/tide_pools.html |archive-url=https://web.archive.org/web/20080924061051/http://www.npca.org/marine_and_coastal/beaches/tide_pools.html |archive-date=2008-09-24 }}</ref> Tide pools contain complex [[food web]]s that can vary based on the climate.<ref>{{Cite journal |last1=Mendonça |first1=Vanessa |last2=Madeira |first2=Carolina |last3=Dias |first3=Marta |last4=Vermandele |first4=Fanny |last5=Archambault |first5=Philippe |last6=Dissanayake |first6=Awantha |last7=Canning-Clode |first7=João |last8=Flores |first8=Augusto A. V. |last9=Silva |first9=Ana |last10=Vinagre |first10=Catarina |date=2018-07-05 |editor-last=Hewitt |editor-first=Judi |title=What's in a tide pool? Just as much food web network complexity as in large open ecosystems |journal=PLOS ONE |language=en |volume=13 |issue=7 |article-number=e0200066 |doi=10.1371/journal.pone.0200066 |issn=1932-6203 |pmc=6033428 |pmid=29975745 |bibcode=2018PLoSO..1300066M |doi-access=free }}</ref>
== Ecological roles == [[File:Scheme eutrophication-en.svg|thumb|upright=1.2|right| {{center|Effect of [[eutrophication]]<br />on marine benthic life}}]]
===Nutrient flux=== Sources of food for benthic communities can derive from the water column above these habitats in the form of aggregations of [[detritus]], inorganic matter, and living organisms.<ref>Godson (2022) p.90</ref> These aggregations are commonly referred to as [[marine snow]], and are important for the deposition of organic matter, and bacterial communities.<ref>{{cite journal|last=Alldredge|first=Alice|author2=Silver, Mary W.|title=Characteristics, dynamics and significance of marine snow|journal=Progress in Oceanography|year=1988|volume=20|issue=1|pages=41–82|doi=10.1016/0079-6611(88)90053-5|bibcode=1988PrOce..20...41A}}</ref> The amount of material sinking to the ocean floor can average 307,000 aggregates{{clarify|what as considered an "aggregate"?|date=December 2025}} per m<sup>2</sup> per day.<ref>{{cite journal|last=Shanks|first=Alan|author2=Trent, Jonathan D.|title=Marine snow: sinking rates and potential role in vertical flux|journal=Deep-Sea Research|year=1980|volume=27A|pages=137–143|doi=10.1016/0198-0149(80)90092-8|issue=2|bibcode=1980DSRA...27..137S}}</ref> This amount will vary on the depth of the benthos, and the degree of benthic-pelagic coupling. The benthos in a shallow region will have more available food than the benthos in the deep sea. Because of their reliance on it, microbes may become spatially dependent on detritus in the benthic zone. The [[microbes]] found in the benthic zone, specifically [[dinoflagellates]] and [[foraminifera]], colonize quite rapidly on detritus matter while forming a symbiotic relationship with each other.<ref>{{cite web | url=http://bprc.osu.edu/geo/projects/foram/whatarefor.htm | title=Foraminifera | access-date=7 December 2014}}</ref><ref>{{cite web | url=http://www.ucl.ac.uk/GeolSci/micropal/foram.html#histofstudy | title=foraminifera | access-date=7 December 2014}}</ref> In the deep sea, which covers 90–95% of the ocean floor, 90% of the total biomass is made up of prokaryotes. To release all the nutrients locked inside these microbes to the environment, viruses are important in making it available to other organisms.<ref>{{cite book | url=https://books.google.com/books?id=lXy_EAAAQBAJ&dq=deep-sea+sediments+deep+sea+prokaryotes+90%25+biomass+viral&pg=PT273 | title=Organisms Amplify Diversity: An Autocatalytic Hypothesis | isbn=978-1-000-82638-8 | last1=Seaborg | first1=David | date=30 June 2023 | publisher=CRC Press }}</ref><ref>{{cite journal | pmc=4928989 | date=2016 | last1=Danovaro | first1=R. | last2=Molari | first2=M. | last3=Corinaldesi | first3=C. | last4=Dell'Anno | first4=A. | title=Macroecological drivers of archaea and bacteria in benthic deep-sea ecosystems | journal=Science Advances | volume=2 | issue=4 | article-number=e1500961 | doi=10.1126/sciadv.1500961 | pmid=27386507 | bibcode=2016SciA....2E0961D }}</ref>
The main food sources for the benthos are [[phytoplankton]] and organic detrital matter.<ref>{{Citation |last=Smetacek |first=Victor |title=The Supply of Food to the Benthos |date=1984 |work=Flows of Energy and Materials in Marine Ecosystems: Theory and Practice |pages=517–547 |editor-last=Fasham |editor-first=M. J. R. |url=https://link.springer.com/chapter/10.1007/978-1-4757-0387-0_20 |access-date=2024-09-23 |place=Boston, MA |publisher=Springer US |language=en |doi=10.1007/978-1-4757-0387-0_20 |isbn=978-1-4757-0387-0|url-access=subscription }}</ref><ref>{{Citation |last=Snelgrove |first=Paul V.R. |title=Marine Sediments |date=2013 |encyclopedia=Encyclopedia of Biodiversity |pages=105–115 |url=http://dx.doi.org/10.1016/b978-0-12-384719-5.00008-3 |access-date=2024-09-23 |publisher=Elsevier |doi=10.1016/b978-0-12-384719-5.00008-3 |isbn=978-0-12-384720-1|url-access=subscription }}</ref> In coastal locations, organic run off from land provides an additional food source.<ref>{{Cite web |title=Benthos |url=https://www.britannica.com/science/benthos |access-date=2024-09-23 |website=Encyclopedia Britannica |language=en}}</ref> Meiofauna and bacteria consume and recycle organic matter in the sediments, playing an important role in returning [[nitrate]] and [[phosphate]] to the pelagic.<ref>{{Citation |last=Nunnally |first=Clifton C. |title=Benthic–Pelagic Coupling: Linkages Between Benthic Ecology and Biogeochemistry and Pelagic Ecosystems and Process |date=2019 |encyclopedia=Encyclopedia of Ocean Sciences |pages=660–662 |url=https://www.sciencedirect.com/topics/earth-and-planetary-sciences/benthic-pelagic-coupling |access-date=2024-09-23 |publisher=Elsevier |language=en |doi=10.1016/B978-0-12-409548-9.11087-5 |isbn=978-0-12-813082-7|url-access=subscription }}</ref>
The depth of water, temperature and salinity, and type of local substrate all affect what benthos is present. In coastal waters and other places where light reaches the bottom, benthic [[photosynthesis|photosynthesizing]] [[diatoms]] can proliferate. [[Filter feeder]]s, such as [[sponge]]s and [[bivalve]]s, dominate hard, sandy bottoms. Deposit feeders, such as [[polychaete]]s, populate softer bottoms. Fish, such as [[dragonets]], as well as [[sea star]]s, [[snail]]s, [[cephalopod]]s, and [[crustacean]]s are important predators and scavengers.
Benthic organisms, such as [[sea star]]s, [[oyster]]s, [[clam]]s, [[Holothuroidea|sea cucumber]]s, [[brittle star]]s and [[sea anemone]]s, play an important role as a food source for [[fish]], such as the [[California sheephead]], and [[human]]s.
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===Carbon processing=== <gallery mode="packed" style="float:right" heights="300px" caption="Carbon processing in marine sediments"> File:Carbon processing in marine sediments.jpg </gallery>
Organic matter produced in the sunlit layer of the ocean and delivered to the sediments is either consumed by organisms or buried. The organic matter consumed by organisms is used to synthesize [[Biomass (ecology)|biomass]] (i.e. growth) converted to carbon dioxide through [[Respiration (physiology)|respiration]], or returned to the sediment as faeces. This cycle can occur many times before either all organic matter is used up or eventually buried. This process is known as the [[biological pump]].<ref>{{Citation |last1=Sigman |first1=D.M. |title=The Biological Pump in the Past |date=2003 |journal=Treatise on Geochemistry |pages=491–528 |url=http://dx.doi.org/10.1016/b0-08-043751-6/06118-1 |access-date=2024-09-22 |publisher=Elsevier |isbn=978-0-08-043751-4 |last2=Haug |first2=G.H.|volume=6 |doi=10.1016/b0-08-043751-6/06118-1 |bibcode=2003TrGeo...6..491S |url-access=subscription }}</ref><ref name="Middelburg2018">{{cite journal | last=Middelburg | first=Jack J. | title=Reviews and syntheses: to the bottom of carbon processing at the seafloor | journal=Biogeosciences | publisher=Copernicus GmbH | volume=15 | issue=2 | date=19 January 2018 | issn=1726-4189 | doi=10.5194/bg-15-413-2018 | pages=413–427| bibcode=2018BGeo...15..413M | doi-access=free }} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref>
In the long-term or at steady-state, i.e., the biomass of benthic organisms does not change, the benthic community can be considered a black box diverting organic matter into either metabolites or the geosphere (burial).<ref name="Middelburg2018" /> The macrobenthos also indirectly impacts carbon cycling on the seafloor through [[bioturbation]].<ref>{{Cite journal |last1=Sun |first1=Ming-Yi |last2=Dai |first2=Jihong |date=2005-09-01 |title=Relative influences of bioturbation and physical mixing on degradation of bloom-derived particulate organic matter: Clue from microcosm experiments |url=https://www.sciencedirect.com/science/article/abs/pii/S030442030500006X |journal=Marine Chemistry |volume=96 |issue=3 |pages=201–218 |doi=10.1016/j.marchem.2004.11.003 |bibcode=2005MarCh..96..201S |issn=0304-4203|url-access=subscription }}</ref>
=== As bioindicators === Benthic macro-invertebrates play a critical role in [[aquatic ecosystem]]s. These organisms can be used to indicate the presence, [[concentration]], and effect of water pollutants in the aquatic environment. Some water contaminants—such as nutrients, chemicals from [[surface runoff]], and metals<ref>{{Cite web |title=Major Contaminants {{!}} Contaminated Sediments {{!}} US EPA |url=https://archive.epa.gov/water/archive/polwaste/web/html/contaminants.html |access-date=2022-10-12 |website=archive.epa.gov |language=en}}</ref>—settle in the [[sediment]] of river beds, where many benthos reside. Benthos are highly sensitive to contamination, so their close proximity to high pollutant concentrations make these organisms ideal for studying water contamination.<ref>{{Cite journal |last1=Rodrigues |first1=Carolina |last2=Guimarães |first2=Laura |last3=Vieira |first3=Natividade |date=2019-08-01 |title=Combining biomarker and community approaches using benthic macroinvertebrates can improve the assessment of the ecological status of rivers |url=https://doi.org/10.1007/s10750-019-03991-7 |journal=Hydrobiologia |language=en |volume=839 |issue=1 |pages=1–24 |doi=10.1007/s10750-019-03991-7 |bibcode=2019HyBio.839....1R |s2cid=186207664 |issn=1573-5117|url-access=subscription }}</ref>
Benthos can be used as [[bioindicator]]s of [[water pollution]] through ecological population assessments or through analyzing [[biomarker]]s. In ecological population assessments, a relative value of water pollution can be detected. Observing the number and diversity of macro-invertebrates in a waterbody can indicate the pollution level. In highly contaminated waters, a reduced number of organisms and only pollution-tolerant species will be found.<ref>{{Cite web |last=US EPA |first=OW |date=2013-11-21 |title=Indicators: Benthic Macroinvertebrates |url=https://www.epa.gov/national-aquatic-resource-surveys/indicators-benthic-macroinvertebrates |access-date=2022-10-14 |website=[[United States Environmental Protection Agency]] |language=en}}</ref> In biomarker assessments, [[Quantitative research|quantitative]] data can be collected on the amount of and direct effect of specific pollutants in a waterbody. The [[Biochemistry|biochemical]] response of macro-invertebrates' internal tissues can be studied extensively in the laboratory. The concentration of a chemical can cause many changes, including changing feeding behaviors,<ref>{{Cite journal |date=2005-12-01 |title=Water Research |journal=Water Research |language=en |volume=39 |issue=20 |pages=II |doi=10.1016/S0043-1354(05)00684-6 |issn=0043-1354|doi-access= |bibcode=2005WatRe..39D...2. }}</ref> [[inflammation]], and genetic damage,<ref>{{Cite journal |date=August 2004 |title=Online Submission and Review for Science of the Total Environment |journal=Science of the Total Environment |language=en |volume=329 |issue=1–3 |pages=1 |doi=10.1016/j.scitotenv.2004.06.001|bibcode=2004ScTEn.329....1. |doi-access= }}</ref> effects that can be detected outside of the stream environment. Biomarker analysis is important for mitigating the negative impacts of water pollution because it can detect water pollution before it has a noticeable ecological effect on benthos populations.<ref>{{Cite journal |last1=Damásio |first1=Joana |last2=Fernández-Sanjuan |first2=Maria |last3=Sánchez-Avila |first3=Juan |last4=Lacorte |first4=Silvia |last5=Prat |first5=Narcís |last6=Rieradevall |first6=Maria |last7=Soares |first7=Amadeu M.V.M. |last8=Barata |first8=Carlos |date=June 2011 |title=Multi-biochemical responses of benthic macroinvertebrate species as a complementary tool to diagnose the cause of community impairment in polluted rivers |url=https://linkinghub.elsevier.com/retrieve/pii/S0043135411001813 |journal=Water Research |language=en |volume=45 |issue=12 |pages=3599–3613 |doi=10.1016/j.watres.2011.04.006|pmid=21571352 |bibcode=2011WatRe..45.3599D |url-access=subscription }}</ref>
===Other research=== {{aquatic layer topics}}
Benthic [[macroinvertebrate]]s have many important ecological functions, such as regulating the flow of materials and energy in [[river ecosystem]]s through their [[food web]] linkages. Because of this correlation between flow of energy and nutrients, benthic [[macroinvertebrates]] have the ability to influence food resources on fish and other organisms in [[aquatic ecosystems]]. For example, the addition of a moderate amount of [[nutrients]] to a river over the course of several years resulted in increases in invertebrate richness, abundance, and [[Biomass (ecology)|biomass]]. These in turn resulted in increased food resources for native species of fish with insignificant alteration of the macroinvertebrate community structure and [[trophic network|trophic]] pathways.<ref>{{cite journal|last=Minshall |first=Wayne |author2=Shafii, Bahman |author3=Price, William J. |author4=Holderman, Charlie |author5=Anders, Paul J. |author6=Lester, Gary |author7=Barrett, Pat |title=Effects of nutrient replacement on benthic macroinvertebrates in an ultraoligotrophic reach of the Kootenai River, 2003–2010 |journal=Freshwater Science |volume=33 |issue=4 |pages=1009–1023 |jstor=10.1086/677900 |doi=10.1086/677900|year=2014 |s2cid=84495019 |doi-access=free |bibcode=2014FWSci..33.1009M }}</ref> The presence of macroinvertebrates such as [[Amphipoda#Ecology|Amphipoda]] also affect the dominance of certain types of algae in Benthic ecosystems as well.<ref>{{Cite journal|title = Strong impacts of grazing amphipods on the organization of a benthic community|journal = Ecological Monographs|date = 2000-05-01|issn = 0012-9615|pages = 237–263|volume = 70|issue = 2|doi = 10.1890/0012-9615(2000)070[0237:SIOGAO]2.0.CO;2|first1 = J. Emmett|last1 = Duffy|first2 = Mark E.|last2 = Hay|citeseerx = 10.1.1.473.4746| s2cid=54598097 }}</ref> In addition, because benthic zones are influenced by the flow of dead [[organic matter|organic material]], there have been studies conducted on the relationship between stream and river water flows and the resulting effects on the benthic zone. Low flow events show a restriction in nutrient transport from benthic [[substrate (marine biology)|substrates]] to food webs, and caused a decrease in benthic macroinvertebrate biomass, which lead to the disappearance of food sources into the substrate.<ref>{{cite journal|last=Rolls |first=Robert |author2=Leigh, Catherine |author3=Sheldon, Fran |title=Mechanistic effects of low-flow hydrology on riverine ecosystems: ecological principles and consequences of alteration |journal=Freshwater Science |year=2012 |volume=31 |pages=1163–1186 |issue=4 |jstor=10.1899/12-002.1 |doi=10.1899/12-002.1|bibcode=2012FWSci..31.1163R |hdl=10072/48539 |s2cid=55593045 |hdl-access=free }}</ref>
Because the benthic system regulates energy in aquatic ecosystems, studies have been made of the mechanisms of the benthic zone in order to better understand the ecosystem. Benthic [[diatom]]s have been used by the European Union's [[Water Framework Directive]] (WFD) to establish ecological quality ratios that determined the ecological status of lakes in the UK.<ref>{{cite journal|last=Bennion |first=Helen |author2=Kelly, Martyn G. |author3=Juggins, Steve |author4=Yallop, Marian L. |author5=Burgess, Amy |author6=Jamieson, Jane |author7=Krokowski, Jan |title=Assessment of Ecological Status in UK lakes using benthic diatoms|journal=Freshwater Science |year=2014 |volume=33 |pages=639–654 |jstor=10.1086/675447 |doi=10.1086/675447|issue=2|bibcode=2014FWSci..33..639B |hdl=1983/d42210cd-45e2-48a6-87ed-e2d3cbd3f23b |s2cid=33631675 |url=http://research-information.bristol.ac.uk/files/88889408/Bennionetal.pdf }}</ref> Beginning research is being made on benthic assemblages to see if they can be used as indicators of healthy aquatic ecosystems. Benthic assemblages in urbanized coastal regions are not functionally equivalent to benthic assemblages in untouched regions.<ref>{{cite journal|last=Lowe |first=Michael |author2=Peterson, Mark S. |title=Effects of Coastal Urbanization on Salt-Marsh Faunal Assemblages in the Northern Gulf of Mexico |journal= Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science |year=2014 |volume=6 |issue=1 |pages=89–107 |doi=10.1080/19425120.2014.893467|doi-access=free |bibcode=2014MCFis...6...89L |hdl=1912/6981 |hdl-access=free }}</ref>
Ecologists are attempting to understand the relationship between [[heterogeneity]] and maintaining [[biodiversity]] in aquatic ecosystems. Benthic [[algae]] has been used as an inherently good subject for studying short term changes and community responses to heterogeneous conditions in streams. Understanding the potential mechanisms involving benthic [[periphyton]] and the effects on heterogeneity within a stream may provide a better understanding of the structure and function of stream ecosystems.<ref>{{cite journal|last=Wellnitz |first=Todd |author2=Rader, Russell B. |title=Mechanisms influencing community composition and succession in mountain stream periphyton: interactions between scouring history, grazing, and irradiance |journal=Journal of the North American Benthological Society |year=2003 |volume=22 |pages=528–541 |doi=10.2307/1468350|issue=4 |jstor=1468350 |s2cid=85061936 }}</ref> Periphyton populations suffer from high natural [[spatial variability]] while difficult accessibility simultaneously limits the practicable number of samples that can be taken. Targeting periphyton locations which are known to provide reliable samples {{endash}} especially hard surfaces {{endash}} is recommended in the [[European Union]] benthic monitoring program (by Kelly 1998 for the United Kingdom then in the EU and for the EU as a whole by CEN 2003 and CEN 2004) and in some United States programs (by Moulton et al. 2002).<ref name="Smol-2010">{{cite book | last=Smol | first=John P. | title=The Diatoms: Applications for the Environmental and Earth Sciences | publisher=[[Cambridge University Press]] (CUP) | publication-place=[[Cambridge]] [[New York City]] | year=2010 | isbn=978-0-521-50996-1 | oclc=671782244}}</ref>{{rp|60}} Benthic [[gross primary production]] (GPP) may be important in maintaining biodiversity hotspots in [[littoral zone]]s in large [[lake ecosystem]]s. However, the relative contributions of benthic habitats within specific ecosystems are poorly explored and more research is planned.<ref>{{cite journal|last=Althouse |first=Bryan |author2=Higgins, Scott |author3=Vander Zanden, Jake M. |title=Benthic and Planktonic primary production along a nutrient gradient in Green Bay, Lake Michigan, USA |journal=Freshwater Science |year=2014 |volume=33 |pages=487–498 |jstor=10.1086/676314 |doi=10.1086/676314|issue=2|s2cid=84535584 |doi-access=free |bibcode=2014FWSci..33..487A }}</ref>
== Threats and mitigation== {{see also|Bottom trawling}}
Benthos are negatively impacted by [[fishing]], [[pollution]] and litter, [[Deep sea mining|deep-sea mining]], oil and gas activities, [[tourism]], [[shipping]], [[invasive species]], [[climate change]] (and its impacts such as [[ocean acidification]], [[ocean warming]] and changes to [[Ocean current|ocean circulation]]) and construction such as [[Coastal development hazards|coastal development]], [[Submarine cable|undersea cables]], and [[wind farm]] construction.<ref>{{Citation |last=Harris |first=Peter T. |title=Chapter 3 - Anthropogenic threats to benthic habitats |date=2020-01-01 |work=Seafloor Geomorphology as Benthic Habitat (Second Edition) |pages=35–61 |editor-last=Harris |editor-first=Peter T. |url=https://www.sciencedirect.com/science/article/abs/pii/B9780128149607000038 |access-date=2024-09-24 |publisher=Elsevier |isbn=978-0-12-814960-7 |editor2-last=Baker |editor2-first=Elaine}}</ref>
[[File:Abiotic and biotic responses to a trawl ban.webp|thumb|upright=2.4|left|Abiotic and biotic responses to a territory-wide trawl ban in Hong Kong waters. Abiotic responses: (1) lower bottom water suspended-solid loads, (2) higher sedimentary organic contents; and biotic responses include: (3) higher site-based abundance, species richness, functional diversity, niche occupancy and among-site similarity of macrobenthos.<ref name="Zhi12021">{{cite journal | last1=Wang | first1=Zhi | last2=Leung | first2=Kenneth M. Y. | last3=Sung | first3=Yik-Hei | last4=Dudgeon | first4=David | last5=Qiu | first5=Jian-Wen | title=Recovery of tropical marine benthos after a trawl ban demonstrates linkage between abiotic and biotic changes | journal=Communications Biology | volume=4 | issue=1 | date=2021-02-16 | issn=2399-3642 | pmid=33594207 | pmc=7887210 | doi=10.1038/s42003-021-01732-y | article-number=212 }} [[File:CC-BY icon.svg|50px]] Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref>]]
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[[Bottom trawling]] accounts for roughly 25% of global capture fisheries.<ref name="FAO2016">FAO. 2016. [https://openknowledge.fao.org/server/api/core/bitstreams/20e618b3-93a1-488a-9697-798f6b6c6b35/content#:~:text=Recommended%20citation%3A,security%20and%20nutrition%20for%20all. The State of World Fisheries and Aquaculture 2016], Rome. {{isbn|978-92-5-109185-2}}.</ref> It has increasingly been recognized as a [[sustainable fishing|non-sustainable fishing]] practice.<ref name="de Groot1984">{{cite journal | last=de Groot | first=S.J. | title=The impact of bottom trawling on benthic fauna of the North Sea | journal=Ocean Management | volume=9 | issue=3–4 | date=1984 | doi=10.1016/0302-184X(84)90002-7 | pages=177–190 | bibcode=1984OcMan...9..177D | url=https://linkinghub.elsevier.com/retrieve/pii/0302184X84900027 | access-date=2026-03-17| url-access=subscription }}</ref><ref name="Dayton1995">{{cite journal | last1=Dayton | first1=Paul K. | last2=Thrush | first2=Simon F. | last3=Agardy | first3=M. Tundi | last4=Hofman | first4=Robert J. | title=Environmental effects of marine fishing | journal=Aquatic Conservation: Marine and Freshwater Ecosystems | date=1995 | volume=5 | issue=3 | pages=205–232 | doi=10.1002/aqc.3270050305 | bibcode=1995ACMFE...5..205D | url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/aqc.3270050305 | url-access=subscription }}</ref><ref name="Kumar2006">Kumar, A.B. and Deepthi, G.R., 2006. [https://scholar.google.co.nz/scholar?hl=en&as_sdt=0%2C5&q=Trawling+and+by-catch%3A+implications+on+marine+ecosystem&btnG= "Trawling and by-catch: Implications on marine ecosystem. Current Science"], '''90'''(8), pages 922–931. Access date=17 March 2026.</ref><ref name="Foden2011">{{cite journal | last1=Foden | first1=J | last2=Rogers | first2=Si | last3=Jones | first3=Ap | title=Human pressures on UK seabed habitats: a cumulative impact assessment | journal=Marine Ecology Progress Series | volume=428 | date=2011-05-03 | issn=0171-8630 | doi=10.3354/meps09064 | pages=33–47 | bibcode=2011MEPS..428...33F | url=http://www.int-res.com/abstracts/meps/v428/p33-47/ | access-date=2026-03-17}}</ref> It impacts benthic ecosystems in two ways. First, [[fishing gear]] disrupts epibenthic sediments, resulting in the loss of habitat complexity and resuspension of sediments into the [[water column]],<ref name="Jones1992">{{cite journal | last=Jones | first=J. B. | title=Environmental impact of trawling on the seabed: A review | journal=New Zealand Journal of Marine and Freshwater Research | volume=26 | issue=1 | date=1992 | issn=0028-8330 | doi=10.1080/00288330.1992.9516500 | pages=59–67 | bibcode=1992NZJMF..26...59J | url=https://rsnz.onlinelibrary.wiley.com/doi/10.1080/00288330.1992.9516500 | access-date=2026-03-17| url-access=subscription }}</ref><ref name="Thrush2002">{{cite journal | last1=Thrush | first1=Simon F. | last2=Dayton | first2=Paul K. | title=Disturbance to Marine Benthic Habitats by Trawling and Dredging: Implications for Marine Biodiversity | journal=Annual Review of Ecology and Systematics | volume=33 | issue=1 | date=2002 | issn=0066-4162 | doi=10.1146/annurev.ecolsys.33.010802.150515 | pages=449–473 | bibcode=2002AnRES..33..449T | url=https://www.annualreviews.org/doi/10.1146/annurev.ecolsys.33.010802.150515 | access-date=2026-03-23| url-access=subscription }}</ref><ref name="Hiddink2017">{{cite journal | last1=Hiddink | first1=Jan Geert | last2=Jennings | first2=Simon | last3=Sciberras | first3=Marija | last4=Szostek | first4=Claire L. | last5=Hughes | first5=Kathryn M. | last6=Ellis | first6=Nick | last7=Rijnsdorp | first7=Adriaan D. | last8=McConnaughey | first8=Robert A. | last9=Mazor | first9=Tessa | last10=Hilborn | first10=Ray | last11=Collie | first11=Jeremy S. | last12=Pitcher | first12=C. Roland | last13=Amoroso | first13=Ricardo O. | last14=Parma | first14=Ana M. | last15=Suuronen | first15=Petri | last16=Kaiser | first16=Michel J. | title=Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance | journal=Proceedings of the National Academy of Sciences | volume=114 | issue=31 | date=2017 | issn=0027-8424 | pmid=28716926 | pmc=5547586 | doi=10.1073/pnas.1618858114 | pages=8301–8306 | doi-access=free | bibcode=2017PNAS..114.8301H }}</ref> reducing the sedimentary organic-matter content,<ref name="Pusceddu2005">{{cite journal | last1=Pusceddu | first1=A. | last2=Grémare | first2=A. | last3=Escoubeyrou | first3=K. | last4=Amouroux | first4=J.M. | last5=Fiordelmondo | first5=C. | last6=Danovaro | first6=R. | title=Impact of natural (storm) and anthropogenic (trawling) sediment resuspension on particulate organic matter in coastal environments | journal=Continental Shelf Research | volume=25 | issue=19–20 | date=2005 | doi=10.1016/j.csr.2005.08.012 | pages=2506–2520 | bibcode=2005CSR....25.2506P | url=https://linkinghub.elsevier.com/retrieve/pii/S0278434305001433 | access-date=2026-03-25| url-access=subscription }}</ref> and increasing [[turbidity]] and biochemical oxygen demand in the water column.<ref name="Palanques2001">{{cite journal | last1=Palanques | first1=A. | last2=Guillén | first2=J. | last3=Puig | first3=P. | title=Impact of bottom trawling on water turbidity and muddy sediment of an unfished continental shelf | journal=Limnology and Oceanography | volume=46 | issue=5 | date=2001 | issn=0024-3590 | doi=10.4319/lo.2001.46.5.1100 | pages=1100–1110 | doi-access=free | bibcode=2001LimOc..46.1100P }}</ref><ref name="Riemann1991">Riemann, B. and Hoffmann, E., 1991. [https://www.int-res.com/articles/meps/69/m069p171.pdf "Ecological consequences of dredging and bottom trawling in the Limfjord, Denmark"]. Marine ecology progress series, 69, pages 171–178. Access date 17 March 2026.</ref> Second, trawling disrupts benthic community structure, selectively removing large-bodied target and non-target species, which are usually [[K-selected]], resulting in a community dominated by relatively small [[r-selected]] species.<ref name="Kaiser2000">{{cite journal | last1=Kaiser | first1=M. J. | last2=Ramsay | first2=K. | last3=Richardson | first3=C. A. | last4=Spence | first4=F. E. | last5=Brand | first5=A. R. | title=Chronic fishing disturbance has changed shelf sea benthic community structure | journal=Journal of Animal Ecology | volume=69 | issue=3 | date=2000 | issn=0021-8790 | doi=10.1046/j.1365-2656.2000.00412.x | pages=494–503 | bibcode=2000JAnEc..69..494K | url=https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.2000.00412.x | access-date=2026-03-25| url-access=subscription }}</ref><ref name="Jennings2001">{{cite journal | last1=Jennings | first1=Simon | last2=Dinmore | first2=Tracy A. | last3=Duplisea | first3=Daniel E. | last4=Warr | first4=Karema J. | last5=Lancaster | first5=John E. | title=Trawling disturbance can modify benthic production processes | journal=Journal of Animal Ecology | volume=70 | issue=3 | date=2001 | issn=0021-8790 | doi=10.1046/j.1365-2656.2001.00504.x | pages=459–475 | bibcode=2001JAnEc..70..459J | url=https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.2001.00504.x | access-date=2026-03-25}}</ref> Given the significance of these impacts, a number of countries have implemented total or partial bans on bottom trawling within their [[territorial waters]]{{hsp}}<ref name="Pipitone2000">{{cite journal | last1=Pipitone | first1=Carlo | last2=Badalamenti | first2=Fabio | last3=D’Anna | first3=Giovanni | last4=Patti | first4=Bernardo | title=Fish biomass increase after a four-year trawl ban in the Gulf of Castellammare (NW Sicily, Mediterranean Sea) | journal=Fisheries Research | volume=48 | issue=1 | date=2000 | doi=10.1016/S0165-7836(00)00114-4 | pages=23–30 | bibcode=2000FishR..48...23P | url=https://linkinghub.elsevier.com/retrieve/pii/S0165783600001144 | access-date=2026-03-25| url-access=subscription }}</ref><ref name="Pranovi2015">{{cite journal | last1=Pranovi | first1=Fabio | last2=Monti | first2=Marco Anelli | last3=Caccin | first3=Alberto | last4=Brigolin | first4=Daniele | last5=Zucchetta | first5=Matteo | title=Permanent trawl fishery closures in the Mediterranean Sea: An effective management strategy? | journal=Marine Policy | volume=60 | date=2015 | doi=10.1016/j.marpol.2015.07.003 | pages=272–279 | bibcode=2015MarPo..60..272P | url=https://linkinghub.elsevier.com/retrieve/pii/S0308597X15002043 | access-date=2026-03-25| hdl=10278/3660246 | hdl-access=free }}</ref> or in the [[international waters]] they manage.<ref name="Ardron2008">{{cite journal | last1=Ardron | first1=Jeff | last2=Gjerde | first2=Kristina | last3=Pullen | first3=Sian | last4=Tilot | first4=Virginie | title=Marine spatial planning in the high seas | journal=Marine Policy | volume=32 | issue=5 | date=2008 | doi=10.1016/j.marpol.2008.03.018 | pages=832–839 | bibcode=2008MarPo..32..832A | url=https://linkinghub.elsevier.com/retrieve/pii/S0308597X08000729 | access-date=2026-03-17| url-access=subscription }}</ref><ref name="Zhi12021" />
==See also== {{div col|colwidth=20em}} * [[Armor (hydrology)]] * [[Benthic fish]] * [[Benthopelagic fish]] * [[Bioirrigation]] * [[Bottom trawling]] * [[Deep sea]] * [[Deep sea communities]] * [[Deep sea mining]] * [[Demersal fish]] * [[Epibenthic sled]] * [[Intertidal ecology]] * [[Littoral]] * [[Plankton]] * [[Pelagic zone]] * [[Photic zone]] * [[Sediment Profile Imagery]] (SPI) * [[Stream bed]] {{div col end}}
==References== {{reflist}}
==External links== {{commons category|Benthic zones}} *[https://web.archive.org/web/20190909185843/https://www.dassh.ac.uk/ Data Archive for Seabed Species and Habitats] from the UK Marine Data Archive Centre * [http://paleopolis.rediris.es/benthos/ "Benthos"] * [https://www.britannica.com/eb/article-9078658 "Benthos".] (2008) Encyclopædia Britannica. (Retrieved May 15, 2008, from Encyclopædia Britannica Online.) * Ryan, Paddy (2007) [http://www.teara.govt.nz/EarthSeaAndSky/SeaLife/DeepSeaCreatures/4/en "Benthic communities"] {{Webarchive|url=https://web.archive.org/web/20081216001405/http://www.teara.govt.nz/EarthSeaAndSky/SeaLife/DeepSeaCreatures/4/en |date=2008-12-16 }} Te Ara - the Encyclopædia of New Zealand, updated 21 September 2007. * Yip, Maricela and Madl, Pierre (1999) [http://biophysics.sbg.ac.at/rovigno/rovigno2.htm "Benthos"] {{Webarchive|url=https://web.archive.org/web/20190720224223/http://biophysics.sbg.ac.at/rovigno/rovigno2.htm |date=2019-07-20 }} [[University of Salzburg]].
{{physical oceanography|expanded=other}} {{Aquatic ecosystems}} {{Aquatic organisms}} {{Biomes}} {{Authority control}}
{{DEFAULTSORT:Benthic Zone}} [[Category:Aquatic biomes]] [[Category:Aquatic ecology]] [[Category:Fisheries science]] [[Category:Ecology terminology]] [[Category:Marine organisms]] [[Category:Oceanographical terminology]]