Benthos

Part of a series related to
Benthic life
Benthos              Benthopelagic (coupling)        Seabed
By size macrobenthos meiobenthos microbenthos
By type zoobenthos phytobenthos
By location endobenthos epibenthos hyperbenthos
By habitat     Shallow: bivalve reef                    mangrove forest • coral reef                    seagrass meadow         Deep: seamount • cold seep                    hydrothermal vent
Communities Benthic fish Benthopelagic fish Bottom feeder Deep sea Deep sea communities Demersal fish Intertidal ecology Hydrothermal vent microbial communities
Related Epibenthic sled Van Veen grab sampler Bioirrigation Bioturbation Demersal zone Marine sediment
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Benthos (from

Macrobenthos, prefix from

• 
  Seagrass
• 
  Echinoderms
• 
  Sea squirts
• 
  Aquatic

  amphipods

Meiobenthos

• 
  Foraminiferan
• 
  Gastrotrich
• 
  Copepod
• 
  Tardigrade (water bear)

Microbenthos

Microbenthos, prefix from the Greek mikrós 'small', comprises microscopic benthic organisms that are less than about 0.1 mm in size. Some examples are

• 
  Diatoms
• 
  Ciliate
• 
  Dinoflagellates

Marine microbenthos are microorganisms that live in the benthic zone of the ocean – that live near or on the seafloor, or within or on surface seafloor sediments. The word benthos comes from Greek, meaning "depth of the sea". 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 shallow waters, seagrass meadows, coral reefs and kelp forests provide particularly rich habitats. In photic zones benthic diatoms dominate as photosynthetic organisms. In intertidal zones changing tides strongly control opportunities for microbenthos.

• 
  Elphidium a widespread abundant genus of benthic forams
• 
  Heterohelix, an extinct genus of benthic forams

• Marine microanimals
• 
  Darkfield photo of a gastrotrich

  , 0.06-3.0 mm long, a worm-like animal living between sediment particles
• 
  Armoured Pliciloricus enigmaticus, about 0.2 mm long, live in spaces between marine gravel

Both foraminifera and diatoms have

The sudden 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.^[10][11]

Some endoliths 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.^[12] These are slowly metabolizing and not in a dormant state. Some Actinomycetota found in Siberia are estimated to be half a million years old.^[13][14][15]

By type

Zoobenthos

Zoobenthos, prefix from

Phytobenthos

Endobenthos

Endobenthos (or endobenthic), prefix from

The main food sources for the benthos are

Benthic macro-invertebrates play a critical role in aquatic ecosystems. 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^[16]—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.^[17]

Benthos can be used as bioindicators of water pollution through ecological population assessments or through analyzing biomarkers. 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.^[18] In biomarker assessments, quantitative data can be collected on the amount of and direct effect of specific pollutants in a waterbody. The 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,^[19] inflammation, and genetic damage,^[20] 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.^[21]

Carbon processing

• Carbon processing in marine sediments
• 

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 or is metabolized to carbon dioxide and nutrients. 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).^[22]

See also

• Aphotic zone
• Benthic fish
• Benthopelagic fish
• Bioirrigation
• Bottom feeder
• Deep sea
• Deep sea communities
• Deep sea mining
• Demersal fish
• Intertidal ecology
• Littoral
• Neritic zone
• Nekton
• Plankton
• Pelagic zone
• Photic zone
• Profundal zone
• Sediment Profile Imagery (SPI)
• Stream bed

Notes