{{Short description|Organisms that obtain energy by the oxidation of electron donors in their environments}} A '''chemotroph''' is an organism that obtains energy by the oxidation of electron donors in their environments.<ref name="NYT-20160912">{{cite news |last=Chang |first=Kenneth |title=Visions of Life on Mars in Earth's Depths |date=12 September 2016 |work=The New York Times |url=https://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |access-date=12 September 2016}}</ref> These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrophs, which use photons. Chemotrophs can be either autotrophic or heterotrophic. Chemotrophs can be found in areas where electron donors are present in high concentration, for instance around hydrothermal vents.<ref>{{Cite journal |last1=Zeng |first1=Xiang |last2=Alain |first2=Karine |last3=Shao |first3=Zongze |date=January 2021 |title=Microorganisms from deep-sea hydrothermal vents |journal=Marine Life Science & Technology |volume=3 |issue=2 |pages=204–230 |doi=10.1007/s42995-020-00086-4 |issn=2662-1746 |pmc=10077256 |pmid=37073341 |bibcode=2021MLST....3..204Z }}</ref> Some examples of chemotrophic organisms include iron-oxidizing bacteria and methanogenic archaea.
==Chemoautotroph== [[File:Blacksmoker in Atlantic Ocean.jpg|upright|thumb|A black smoker vent in the Atlantic Ocean, providing energy and nutrients for chemotrophs]]
'''Chemoautotrophs''' are autotrophic organisms that can rely on chemosynthesis, i.e. deriving biological energy from chemical reactions of environmental inorganic substrates and synthesizing all necessary organic compounds from carbon dioxide. Chemoautotrophs can use inorganic energy sources such as hydrogen sulfide, elemental sulfur, ferrous iron, molecular hydrogen, and ammonia or organic sources to produce energy. Most chemoautotrophs are prokaryotic extremophiles, bacteria, or archaea that live in otherwise hostile environments (such as deep sea vents) and are the primary producers in such ecosystems. Chemoautotrophs generally fall into several groups: methanogens, sulfur oxidizers and reducers, nitrifiers, anammox bacteria, and thermoacidophiles. An example of one of these prokaryotes would be ''Sulfolobus''. Chemolithotrophic growth can be very fast, such as ''Hydrogenovibrio crunogenus'' with a doubling time around one hour.<ref>{{cite journal |volume=187 |issue=16 |title=The Carbon-Concentrating Mechanism of the Hydrothermal Vent Chemolithoautotroph Thiomicrospira crunogena |year=2005 |journal=Journal of Bacteriology |pages=5761–5766 |last1=Dobrinski |first1=K. P. |pmid=16077123 |doi=10.1128/JB.187.16.5761-5766.2005 |pmc=1196061 |bibcode=2005JBact.187.5761D }}</ref><ref name="boden">{{cite journal |author1=Rich Boden|author2= Kathleen M. Scott|author3= J. Williams|author4= S. Russel|author5= K. Antonen|author6= Alexander W. Rae|author7= Lee P. Hutt |title=An evaluation of ''Thiomicrospira'', ''Hydrogenovibrio'' and ''Thioalkalimicrobium'': reclassification of four species of ''Thiomicrospira'' to each ''Thiomicrorhabdus'' gen. nov. and ''Hydrogenovibrio'', and reclassification of all four species of ''Thioalkalimicrobium'' to ''Thiomicrospira'' |journal=International Journal of Systematic and Evolutionary Microbiology |volume=67 |issue=5 |pages=1140–1151 |date=June 2017 |pmid=28581925 |doi=10.1099/ijsem.0.001855 |doi-access=free |bibcode= 2017IJSEM..67.1140B|hdl=10026.1/8374 |hdl-access=free}}</ref>
The term "chemosynthesis", coined in 1897 by Wilhelm Pfeffer, originally was defined as the energy production by oxidation of inorganic substances in association with autotrophy — what would be named today as ''chemolithoautotrophy''. Later, the term would include also the ''chemoorganoautotrophy'', that is, it can be seen as a synonym of chemoautotrophy.<ref>{{cite book |last1=Kelly |first1=D. P. |last2=Wood |first2=A. P. |year=2006 |chapter=The Chemolithotrophic Prokaryotes |title=The Prokaryotes |pages=441–456 |publisher=Springer |location=New York |chapter-url=https://books.google.com/books?id=kyAZ47ZrazkC&pg=PA441 |isbn=978-0-387-25492-0 |doi=10.1007/0-387-30742-7_15}}</ref><ref>{{cite book |last=Schlegel |first=H. G. |year=1975 |chapter=Mechanisms of Chemo-Autotrophy |title=Marine Ecology |volume=2, Part I |editor-first=O. |editor-last=Kinne |editor-link=Otto Kinne |pages=9–60 |publisher=Wiley-Interscience |isbn=0-471-48004-5 |chapter-url=https://www.int-res.com/archive/me_books/me_vol2_(physiological_mechanisms)_pt1.pdf#page=26}}</ref>
==Chemoheterotroph== '''Chemoheterotrophs''' (or chemotrophic heterotrophs) are unable to fix carbon to form their own organic compounds. Chemoheterotrophs can be '''chemolithoheterotrophs''', utilizing inorganic electron sources such as sulfur, iron, or, much more commonly, '''chemoorganoheterotrophs''', utilizing organic electron sources such as carbohydrates, lipids, and proteins.<ref>{{cite book |last=Davis |first=Mackenzie Leo |title=Principles of environmental engineering and science |year=2004 |publisher=清华大学出版社 |page=133 |isbn=978-7-302-09724-2 |display-authors=etal |url=https://books.google.com/books?id=e0OsNiQthNQC&q=chemoheterotroph&pg=PA133}}</ref><ref>{{cite book |last1=Lengeler |first1=Joseph W. |last2=Drews |first2=Gerhart |last3=Schlegel |first3=Hans Günter |title=Biology of the Prokaryotes |year=1999 |publisher=Georg Thieme Verlag |page=238 |isbn=978-3-13-108411-8 |url=https://books.google.com/books?id=MiwpFtTdmjQC&q=chemolithoheterotroph+sulfur+bacteria&pg=PA238}}</ref><ref>{{cite book |last=Dworkin |first=Martin |title=The Prokaryotes: Ecophysiology and biochemistry |year=2006 |edition=3rd |publisher=Springer |page=989 |isbn=978-0-387-25492-0 |url=https://books.google.com/books?id=uleTr2jKzJMC&q=chemolithoheterotroph+sulfur+bacteria&pg=PA989}}</ref><ref>{{cite book |last1=Bergey |first1=David Hendricks |last2=Holt |first2=John G. |title=Bergey's manual of determinative bacteriology |year=1994 |edition=9th |publisher=Lippincott Williams & Wilkins |page=427 |isbn=978-0-683-00603-2 |url=https://books.google.com/books?id=jtMLzaa5ONcC&q=chemolithotrophic+sulfur+bacteria&pg=PA427}}</ref> Most animals and fungi are examples of chemoheterotrophs, as are some halophiles.<ref>{{Cite journal |last1=Corral |first1=Paulina |last2=Amoozegar |first2=Mohammad A. |last3=Ventosa |first3=Antonio |date=2019-12-30 |title=Halophiles and Their Biomolecules: Recent Advances and Future Applications in Biomedicine |journal=Marine Drugs |volume=18 |issue=1 |pages=33 |doi=10.3390/md18010033 |doi-access=free|issn=1660-3397 |pmc=7024382 |pmid=31906001 |bibcode=2019MarDr..18...33C }}</ref><ref>{{Cite journal |last1=Burgin |first1=Amy J |last2=Yang |first2=Wendy H |last3=Hamilton |first3=Stephen K |last4=Silver |first4=Whendee L |date=February 2011 |title=Beyond carbon and nitrogen: how the microbial energy economy couples elemental cycles in diverse ecosystems |url=https://esajournals.onlinelibrary.wiley.com/doi/10.1890/090227 |journal=Frontiers in Ecology and the Environment |language=en |volume=9 |issue=1 |pages=44–52 |doi=10.1890/090227 |bibcode=2011FrEE....9...44B |issn=1540-9295 |archive-url=http://web.archive.org/web/20250430213225/https://esajournals.onlinelibrary.wiley.com/doi/10.1890/090227 |archive-date=2025-04-30}}</ref>
=== Iron-oxidizing bacteria === {{See also|Iron-oxidizing bacteria}} '''Iron-oxidizing bacteria''' are chemotrophic bacteria that derive energy by oxidizing dissolved ferrous iron. They are known to grow and proliferate in waters containing iron concentrations as low as 0.1 mg/L. However, at least 0.3 ppm of dissolved oxygen is needed to carry out the oxidation.<ref>{{cite book |title=Metallomics and the cell |date=2013 |publisher=Springer |editor-first1=L. |editor-last1=Banci |isbn=978-94-007-5561-1 |location=Dordrecht |oclc=841263185 }}</ref>
Iron has many existing roles in biology not related to redox reactions; examples include iron–sulfur proteins, hemoglobin, and coordination complexes. Iron has a widespread distribution globally and is considered one of the most abundant in the Earth's crust, soil, and sediments.<ref name="Madigan" /> Iron is a trace element in marine environments.<ref name="Madigan">{{cite book |title=Brock biology of microorganisms |last1=Madigan |first1=Michael T. |last2=Martinko |first2=John M. |last3=Stahl |first3=David A. |last4=Clark |first4=David P. |date=2012 |publisher=Benjamim Cummings |isbn=978-0-321-64963-8 |edition=13th |location=Boston |pages=1155}}</ref> Its role as the electron donor for some chemolithotrophs is probably very ancient.<ref>{{cite book |last=Bruslind |first=Linda |date=2019-08-01 |title=General Microbiology |chapter=Chemolithotrophy & Nitrogen Metabolism |language=en |url=https://open.oregonstate.education/generalmicrobiology/chapter/chemolithotrophy-nitrogen-metabolism/}}</ref>
=== Methanogens === '''Methanogens''' are chemotrophic archaea that obtain energy most commonly through CO<sub>2</sub> reduction by H<sub>2</sub> (hydrogenotrophs) or fermentation of acetate (acetoclastic).<ref>{{Cite journal |last1=Nazaries |first1=Loïc |last2=Murrell |first2=J. Colin |last3=Millard |first3=Pete |last4=Baggs |first4=Liz |last5=Singh |first5=Brajesh K. |date=2013 |title=Methane, microbes and models: fundamental understanding of the soil methane cycle for future predictions |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.12149 |journal=Environmental Microbiology |language=en |volume=15 |issue=9 |pages=2395–2417 |doi=10.1111/1462-2920.12149 |pmid=23718889 |bibcode=2013EnvMi..15.2395N |issn=1462-2920|url-access=subscription }}</ref> They are distinct from other bacteria or archea that do not depend on methane synthesis for energy but produce methane as a byproduct of their other metabolic processes.<ref name=":2" /> Methanogens are also different from bacteria and eukarya due to a lack of peptidoglycan in their cell wall, rather methanogens contain either pseudomurein, heteropolysaccharide, or protein-based cell walls.<ref>{{Cite journal |last=Alemneh |first=Tewodros |date=2020-12-07 |title=Review on Methanogenesis and its Role |url=https://irispublishers.com/wjass/fulltext/review-on-methanogenesis-and-its-role.ID.000632.php |journal=World Journal of Agriculture and Soil Science |volume=6 |issue=2 |doi=10.33552/WJASS.2020.06.000632|doi-access=free }}</ref> Species that reduce CO<sub>2</sub> are chemoautotrophs and fix inorganic carbon, however, a few species use organic carbon in the form of acetate, making them chemoheterotrophs.<ref>{{Cite journal |last=Conrad |first=Ralf |date=2020-02-01 |title=Importance of hydrogenotrophic, aceticlastic and methylotrophic methanogenesis for methane production in terrestrial, aquatic and other anoxic environments: A mini review |url=https://www.sciencedirect.com/science/article/pii/S1002016018600529 |journal=Pedosphere |volume=30 |issue=1 |pages=25–39 |doi=10.1016/S1002-0160(18)60052-9 |bibcode=2020Pedos..30...25C |issn=1002-0160|url-access=subscription }}</ref> Methanogens belong to the Methanobacteriota kingdom.<ref name=":0">{{Cite journal |last=Ferry |first=James G. |date=2010-12-01 |title=The chemical biology of methanogenesis |url=https://www.sciencedirect.com/science/article/pii/S0032063310002527 |journal=Planetary and Space Science |volume=58 |issue=14 |pages=1775–1783 |doi=10.1016/j.pss.2010.08.014 |bibcode=2010P&SS...58.1775F |issn=0032-0633|url-access=subscription }}</ref> Methanogens are a part of an ancient monophyletic lineage, the Methanobacteriati phylum (formerly "Euryarcheota"), and can be classified into three classes, six orders, twelve families and thirty-five genera.<ref>{{Cite journal |last=Oren |first=Aharon |date=2024-03-11 |title=On validly published names, correct names, and changes in the nomenclature of phyla and genera of prokaryotes: a guide for the perplexed |journal=npj Biofilms and Microbiomes |language=en |volume=10 |issue=1 |article-number=20 |doi=10.1038/s41522-024-00494-9 |pmid=38467688 |pmc=10928132 |issn=2055-5008}}</ref><ref>{{Cite journal |last1=Nazaries |first1=Loïc |last2=Murrell |first2=J. Colin |last3=Millard |first3=Pete |last4=Baggs |first4=Liz |last5=Singh |first5=Brajesh K. |date=2013-04-29 |title=Methane, microbes and models: fundamental understanding of the soil methane cycle for future predictions |url=https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.12149 |journal=Environmental Microbiology |language=en |volume=15 |issue=9 |pages=2395–2417 |doi=10.1111/1462-2920.12149 |pmid=23718889 |bibcode=2013EnvMi..15.2395N |issn=1462-2912|url-access=subscription }}</ref> Methanogenic metabolic pathways are thought to be present in some of the earliest organisms that occupied the earth.<ref>{{Cite book |title=Biogeochemistry |url=http://www.sciencedirect.com:5070/book/monograph/9780128146088/biogeochemistry?via=ihub%3D |access-date=2026-02-27 | date=2020 |language=en |doi=10.1016/C2017-0-00311-7 | isbn=978-0-12-814608-8 }}</ref><ref>{{Cite journal |last1=Taubner |first1=Ruth-Sophie |last2=Schleper |first2=Christa |last3=Firneis |first3=Maria G. |last4=Rittmann |first4=Simon K.-M. R. |date=2015-12-03 |title=Assessing the Ecophysiology of Methanogens in the Context of Recent Astrobiological and Planetological Studies |journal=Life (Basel, Switzerland) |volume=5 |issue=4 |pages=1652–1686 |doi=10.3390/life5041652 |doi-access=free |issn=2075-1729 |pmc=4695842 |pmid=26703739 |bibcode=2015Life....5.1652T }}</ref> Today, methanogens can be found in a wide range of environments, both oxic and anoxic and both terrestrial and aquatic, especially environments containing low sulfate.<ref name=":1">{{Cite journal |last1=Guerrero-Cruz |first1=Simon |last2=Vaksmaa |first2=Annika |last3=Horn |first3=Marcus A. |last4=Niemann |first4=Helge |last5=Pijuan |first5=Maite |last6=Ho |first6=Adrian |date=2021-05-14 |title=Methanotrophs: Discoveries, Environmental Relevance, and a Perspective on Current and Future Applications |journal=Frontiers in Microbiology |language=English |volume=12 |article-number=678057 |doi=10.3389/fmicb.2021.678057 |doi-access=free|pmid=34054786 |pmc=8163242 |issn=1664-302X}}</ref><ref name=":2">{{Cite journal |last=Buan |first=Nicole R. |date=2018-12-14 |editor-last=Robinson |editor-first=Nicholas P. |title=Methanogens: pushing the boundaries of biology |url=https://portlandpress.com/emergtoplifesci/article/2/4/629/77362/Methanogens-pushing-the-boundaries-of-biology |journal=Emerging Topics in Life Sciences |language=en |volume=2 |issue=4 |pages=629–646 |doi=10.1042/ETLS20180031 |issn=2397-8554 |pmc=7289024 |pmid=33525834 |bibcode=2018ETLS....2..629B }}</ref> Their activity is strongly regulated by temperature, pH, substrate and nutrient availability, as well as competition with other anaerobic microbes, all of which influence their distribution across diverse environments.<ref>{{Cite journal |last1=Bueno de Mesquita |first1=Clifton P. |last2=Wu |first2=Dongying |last3=Tringe |first3=Susannah G. |date=2023-01-24 |title=Methyl-Based Methanogenesis: an Ecological and Genomic Review |journal=Microbiology and Molecular Biology Reviews |volume=87 |issue=1 |pages=e00024–22 |doi=10.1128/mmbr.00024-22 |pmc=10029344 |pmid=36692297 |bibcode=2023MMBR...8724.22B }}</ref><ref>{{Cite journal |last1=Tomko |first1=Paxton |last2=Ovando-Ovando |first2=Cesar Ivan |last3=Boussagol |first3=Pierre |last4=Santiago-Martínez |first4=Michel Geovanni |last5=Visscher |first5=Pieter T. |date=2026-04-01 |title=Methanogens Through Time and Space: Impact on Earth's Planetary Evolution and Biogeochemistry |journal=Geosciences |language=en |volume=16 |issue=4 |pages=144 |doi=10.3390/geosciences16040144 |doi-access=free |issn=2076-3263}}</ref>
Methanogenic archaea are involved in the late steps of degradation of organic matter.<ref name=":1" /><ref name=":3" /> In many anaerobic environments, methanogens form syntropic relationships with other fermentative bacteria that supply them with substrates such as H2, formate, and acetate.<ref>{{Cite journal |last1=McInerney |first1=Michael J. |last2=Sieber |first2=Jessica R. |last3=Gunsalus |first3=Robert P. |date=2009-11-10 |title=Syntrophy in anaerobic global carbon cycles |journal=Current Opinion in Biotechnology |volume=20 |issue=6 |pages=623–632 |doi=10.1016/j.copbio.2009.10.001 |issn=1879-0429 |pmc=2790021 |pmid=19897353}}</ref> Since the energy yield of methanogenesis is relatively low compared to other processes, methanogenesis does not become the dominant process until the more energy-rich electron acceptors such as O<sub>2</sub>, NO<sub>3</sub><sup>-</sup>, and SO<sub>4</sub><sup>2-</sup> have already been depleted.<ref>{{Cite journal |last1=Burgin |first1=Amy J |last2=Yang |first2=Wendy H |last3=Hamilton |first3=Stephen K |last4=Silver |first4=Whendee L |date=2011 |title=Beyond carbon and nitrogen: how the microbial energy economy couples elemental cycles in diverse ecosystems |url=https://esajournals.onlinelibrary.wiley.com/doi/10.1890/090227 |journal=Frontiers in Ecology and the Environment |language=en |volume=9 |issue=1 |pages=44–52 |doi=10.1890/090227 |bibcode=2011FrEE....9...44B |issn=1540-9295}}</ref> Due to the absence of these electron acceptors, methanogens can then catalyze the final step of the degradation of organic matter which is essential for anaerobic environments.<ref>{{Cite journal |last1=Lyu |first1=Zhe |last2=Whitman |first2=William B |date=2019-10-01 |title=Transplanting the pathway engineering toolbox to methanogens |url=https://www.sciencedirect.com/science/article/pii/S095816691830168X |journal=Current Opinion in Biotechnology |series=Tissue, Cell and Pathway Engineering |volume=59 |pages=46–54 |doi=10.1016/j.copbio.2019.02.009 |pmid=30875664 |osti=1567957 |issn=0958-1669}}</ref> While different organisms may use different substrates, they all share methane as the final metabolic product, and they are all anaerobic.<ref name=":1" /> In addition to CO<sub>2</sub> and acetate, methanogens also use formate, methylamine and other small molecules to produce CH<sub>4</sub>.<ref>{{Cite journal |last1=Enzmann |first1=Franziska |last2=Mayer |first2=Florian |last3=Rother |first3=Michael |last4=Holtmann |first4=Dirk |date=2018-01-04 |title=Methanogens: biochemical background and biotechnological applications |journal=AMB Express |language=en |volume=8 |issue=1 |article-number=1 |doi=10.1186/s13568-017-0531-x |doi-access=free|issn=2191-0855 |pmc=5754280 |pmid=29302756}}</ref> Regardless of the substrate, all methanogenic archaea utilize the enzyme ''methyl-coenzyme M reductase'', which performs the final step of reducing methyl-coenzyme M to methane.<ref name=":0" /><ref name=":3">{{Cite journal |last1=Nazaries |first1=Loïc |last2=Murrell |first2=J. Colin |last3=Millard |first3=Pete |last4=Baggs |first4=Liz |last5=Singh |first5=Brajesh K. |date=29 April 2013 |title=Methane, microbes and models: fundamental understanding of the soil methane cycle for future predictions |url=https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.12149 |journal=Environmental Microbiology |language=en |volume=15 |issue=9 |pages=2395–2417 |doi=10.1111/1462-2920.12149 |pmid=23718889 |bibcode=2013EnvMi..15.2395N |issn=1462-2912|url-access=subscription }}</ref> Methanogens also possess several unique coenzymes such as coenzyme F430 and methanopterin, among others.<ref>{{Cite journal |last1=Welte |first1=Cornelia |last2=Deppenmeier |first2=Uwe |date=2014-07-01 |title=Bioenergetics and anaerobic respiratory chains of aceticlastic methanogens |url=https://www.sciencedirect.com/science/article/pii/S0005272813002168 |journal=Biochimica et Biophysica Acta (BBA) - Bioenergetics |series=18th European Bioenergetics Conference 2014 Lisbon, Portugal |volume=1837 |issue=7 |pages=1130–1147 |doi=10.1016/j.bbabio.2013.12.002 |pmid=24333786 |issn=0005-2728|url-access=subscription }}</ref> Methanogenic activity contributes to methane that is locked in long-term reservoirs such as permafrost, and as climate warming accelerates thawing of frozen soils, methane production by methanogens is expected increase.<ref>{{Cite journal |last1=Offre |first1=Pierre |last2=Spang |first2=Anja |last3=Schleper |first3=Christa |date=2013-09-08 |title=Archaea in Biogeochemical Cycles |url=https://www.annualreviews.org/content/journals/10.1146/annurev-micro-092412-155614 |journal=Annual Review of Microbiology |language=en |volume=67 |issue= |pages=437–457 |doi=10.1146/annurev-micro-092412-155614 |pmid=23808334 |issn=0066-4227|url-access=subscription }}</ref><ref>{{Cite journal |last1=Rivkina |first1=Elizaveta |last2=Shcherbakova |first2=Viktoria |last3=Laurinavichius |first3=Kestas |last4=Petrovskaya |first4=Lada |last5=Krivushin |first5=Kirill |last6=Kraev |first6=Gleb |last7=Pecheritsina |first7=Svetlana |last8=Gilichinsky |first8=David |date= 2007-07-01|title=Biogeochemistry of methane and methanogenic archaea in permafrost: Methane and methanogenic archaea in permafrost |url=https://academic.oup.com/femsec/article-lookup/doi/10.1111/j.1574-6941.2007.00315.x |journal=FEMS Microbiology Ecology |language=en |volume=61 |issue=1 |pages=1–15 |doi=10.1111/j.1574-6941.2007.00315.x |pmid=17428301 }}</ref> As methane has around 25-30 times the global warming potential of CO<sub>2</sub>, methane is one of the greenhouse gases driving climate change that is a source of concern for climate scientists.<ref>{{Cite journal |last=Buan |first=Nicole R. |date=2018-12-14 |title=Methanogens: pushing the boundaries of biology |journal=Emerging Topics in Life Sciences |volume=2 |issue=4 |pages=629–646 |doi=10.1042/ETLS20180031 |issn=2397-8554 |pmc=7289024 |pmid=33525834 |bibcode=2018ETLS....2..629B }}</ref>
==See also== * Chemosynthesis * Lithotroph * Methanogen (feeds on hydrogen) * Methanotroph * RISE project – expedition that discovered high-temperature vent communities
==Notes== {{Reflist}}
==References== 1. Katrina Edwards. ''Microbiology of a Sediment Pond and the Underlying Young, Cold, Hydrologically Active Ridge Flank''. Woods Hole Oceanographic Institution.
2. Coupled Photochemical and Enzymatic Mn(II) Oxidation Pathways of a Planktonic Roseobacter-Like Bacterium. Colleen M. Hansel and Chris A. Francis* Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115. Received 28 September 2005. Accepted 17 February 2006.
{{Modelling ecosystems}}
Category:Biology terminology Category:Microbial growth and nutrition Category:Planktology Category:Trophic ecology