Editing Trichodesmium

{{Short description|Genus of bacteria}}
{{Automatic taxobox
| image = Trichodesmium_bloom_off_Great_Barrier_Reef_2014-03-07_19-59.jpg
| image_caption = ''Trichodesmium'' bloom off the [[Great Barrier Reef]]
| taxon = Trichodesmium
| authority = Ehrenberg ex Gomont, 1892
}}
<div style="float:right;"></div>
'''''Trichodesmium''''', also called '''sea sawdust''', is a genus of [[Filamentation|filamentous]] [[cyanobacteria]]. They are found in nutrient poor [[tropical]] and [[subtropical]] ocean waters (particularly around [[Australia]] and in the [[Red Sea]], where they were first described by [[Captain Cook]]). ''Trichodesmium'' is a [[diazotroph]]; that is, it [[nitrogen fixation|fixes atmospheric nitrogen]] into [[ammonium]], a nutrient used by other organisms. ''Trichodesmium'' is thought to fix nitrogen on such a scale that it accounts for almost half of the nitrogen fixation in marine systems globally.<ref name=":0">{{cite journal|last1=Bergman|first1= B.|last2= Sandh|first2= G.|last3= Lin|first3= S.|last4= Larsson|first4= H.|last5= Carpenter|first5= E. J.|title=''Trichodesmium'' – a widespread marine cyanobacterium with unusual nitrogen fixation properties|journal=FEMS Microbiol. Rev. |year=2012|pages=1–17|doi=10.1111/j.1574-6976.2012.00352.x|pmid= 22928644|volume=37|issue=3|pmc=3655545}}</ref> ''Trichodesmium'' is the only known diazotroph able to fix nitrogen in daylight under aerobic conditions without the use of [[heterocyst]]s.<ref name="Carpenter et al., 1991">{{cite book|editor=Carpenter, E.J.|editor2=Capone, D.G.|editor3=Rueter, J.G.|year=1991 |title=Marine Pelagic Cyanobacteria: ''Trichodesmium'' and other diazothrophs.|publisher=Kluwer Academic Publishers |location=Dordrecht.}}</ref>

''Trichodesmium'' can live as individual filaments, with tens to hundreds of cells strung together, or in colonies consisting of tens to hundreds of filaments clustered together.<ref>{{Cite journal|last1=Capone|first1=Douglas G.|last2=Zehr|first2=Jonathan P.|last3=Paerl|first3=Hans W.|last4=Bergman|first4=Birgitta|last5=Carpenter|first5=Edward J.|date=1997-05-23|title=Trichodesmium, a Globally Significant Marine Cyanobacterium|journal=Science|language=en|volume=276|issue=5316|pages=1221–1229|doi=10.1126/science.276.5316.1221|s2cid=53710858|issn=0036-8075}}</ref> These colonies are visible to the naked eye and sometimes form blooms, which can be extensive on surface waters. These large blooms led to widespread recognition as "sea sawdust/straw". The [[Red Sea]] gets most of its eponymous colouration from the corresponding pigment in ''[[Trichodesmium erythraeum]]''. Colonies of ''Trichodesmium'' provide a pseudobenthic substrate for many small oceanic organisms including [[bacteria]], [[diatoms]], [[dinoflagellates]], [[protozoa]], and [[copepods]] (which are its primary predator); in this way, the genus can support complex microenvironments.

==Species==
There are currently 9 accepted species in the genus ''Trichodesmium'':<ref>{{AlgaeBase genus|name=Trichodesmium|id=43303}}</ref>
*''[[Trichodesmium clevei]]'' <small>(J.Schmidt) Anagnostidis & Komárek</small>
*''[[Trichodesmium contortum]]'' <small>(Wille ex O.Kirchner ) Wille</small><ref name="Wille, 1904">{{cite book|author=Wille, N.|year=1904 |title=Die Schizophyceen der plankton-expedition.Ergebnisse der Plankton-Expedition der Humbol-Stiftung |editor=Hensen,V.}}</ref>
*''[[Trichodesmium erythraeum]]'' <small>Ehrenberg ex Gomont</small><ref name="Ehrenberg, 1830">{{cite journal |author=Ehrenberg,E.O. |year=1830 |title=Neue Beobachtungen über blutartige Erscheinungen in Ägypten, Arabien und Sibirien, nebst einer Übersicht und Kritik der früher bekannnten |url=https://zenodo.org/record/1423534 |journal=Ann Phys Chem |volume=18 |issue=4 |pages=477–514 |bibcode=1830AnP....94..477E |doi=10.1002/andp.18300940402}}</ref>
*''[[Trichodesmium hildebrantii]]'' <small>Gomont</small><ref name="Gomont, 1892" />
*''[[Trichodesmium iwanoffianum]]'' <small>Nygaard</small>
*''[[Trichodesmium lacustre]]'' <small>Klebahn</small>
*''[[Trichodesmium lenticulare]]'' <small>(Lemmermann) Anagnostidis & Komárek</small>
*''[[Trichodesmium scoboideum]]'' <small>A.H.S.Lucas</small>
*''[[Trichodesmium thiebautii]]'' <small>Gomont</small><ref name="Gomont, 1892">{{cite journal|author=Gomont, M.|year=1892 |title=Monographie des oscillariees (Nostocacees Homocystees) I and II. |journal= Ann Sci Nat Bot Ser |volume=7 |issue=15 |pages=263–368}}</ref>

''[[Trichodesmium erythraeum]]'', described by Ehrenberg in 1830, is the [[lectotype]] of the genus. ''T. erythraeum'' is the species responsible for discoloring the [[Red Sea]] during blooms. This is the only sequenced genome in the genus thus far and is the focus of most laboratory studies (''Trichodesmium'' IMS 101).<!-- Deleted image removed: [[File:Trichodesmium erythraeum.jpg|thumb|''Trichodesmium erythraeum'' colony]] -->

==Cell structure==
[[File:Simplefilaments022 Trichodesmium.jpg|thumb|upright=0.5|Illustration]]Like most cyanobacteria, ''Trichodesmium'' has a [[gram-negative bacteria|gram negative cell wall]]. Unlike other [[diazotroph]]ic, filamentous cyanobacteria, ''Trichodesmium'' do not have [[heterocyst]]s—structures found in some filamentous, nitrogen-fixing cyanobacteria which protect the enzyme [[nitrogenase]] from oxygen. This is a unique characteristic among filamentous cyanobacteria which [[nitrogen fixation|fix nitrogen]] in daylight. Photosynthesis occurs using [[phycoerythrin]] – light-harvesting [[phycobiliprotein]] which is normally found within heterocysts in other diazotrophs.

Instead of having localized stacks of [[thylakoids]], ''Trichodesmium'' has unstacked thylakoids found throughout the cell. ''Trichodesmium'' is highly vacuolated and the content and size of the vacuoles shows diurnal variation. Large gas vesicles (either along the periphery as seen in ''T. erythaeum'' or found distributed throughout the cell as seen in ''T. thiebautii'') allow ''Trichodesmium'' to regulate buoyancy in the water column. These gas vesicles can withstand high pressure, presumably those up to 100–200 m in the water column, allowing ''Trichodesmium'' to move vertically through the water column harvesting nutrients.<ref name="Siddiqui et al., 1991">{{cite journal|author1=Siddiqui P.J.A. |author2=Carpenter E.J. |author3=Bergman B. |year=1991|title=''Trichodesmium'': Ultrastructure and protein localization |journal=Marine Pelagic Cyanobacteria: Trichodesmium and Other Diazotrophs |editor1=Carpenter E.J. |editor2=Capone D.G. |editor3=Rueter J.G. }}</ref>

==Nitrogen fixation==
N<sub>2</sub> is the most abundant chemical in the atmosphere. However, diatomic nitrogen is not usable for most biological processes. [[Nitrogen fixation]] is the process of converting atmospheric diatomic nitrogen into biologically usable forms of nitrogen such as [[ammonium]] and [[nitrogen oxide]]s. This process requires a substantial amount of energy (in the form of [[Adenosine triphosphate|ATP]]) in order to break the triple bond between the nitrogen atoms.<ref name="Zehr, 2008">{{cite book|author=Zehr J.P.|year=2008|chapter=Molecular ecological aspects of nitrogen fixation in the marine environment |title= Microbial Ecology of the Oceans |pages=481–525|editor= Kirchmad|doi=10.1002/9780470281840.ch13|isbn=9780470281840}}</ref><!-- Deleted image removed: [[File:Nitrogen fixation reaction.jpg|thumb|Biological reaction for nitrogen fixation showing relative energy (ATP) used during the reaction]] -->

''Trichodesmium''  is the major [[diazotroph]] in marine pelagic systems<ref name="Siddiqui et al., 1991" /> and is an important source of "new" nitrogen in the nutrient poor waters it inhabits. It has been estimated that the global input of nitrogen fixation by ''Trichodesmium'' is approximately 60–80 [[Teragram (unit)|Tg]] (megatonnes or 10<sup>12</sup> grams) N per year.<ref name=":0" /> Nitrogen fixation in ''Trichodesmium'' is unique among diazotrophs because the process occurs concurrently with oxygen production (via photosynthesis<ref name="Carpenter et al., 1991" />). In other [[cyanobacteria]], N<sub>2</sub> and CO<sub>2</sub> reduction are separated either in space (using heterocysts to protect the sensitive [[nitrogenase]] enzyme from oxygen) or time. However, ''Trichodesmium'' lacks heterocysts and nitrogen fixation peaks during daylight hours (following a diel flux initiated in the morning, reaching a maximum fixation rate midday, and ceasing activity at night).<ref name="Siddiqui et al., 1991" /> Since the first realization of this enigma, ''Trichodesmium'' has been the focus of many studies to try and discover how nitrogen fixation is able to occur in the presence of oxygen production without any apparent structure separating the two processes.

Inhibitor studies even revealed that [[photosystem II]] activity is essential for nitrogen fixation in this organism. All this may seem contradictory at first glance, because the enzyme responsible for nitrogen fixation, nitrogenase, is irreversibly inhibited by oxygen. However, ''Trichodesmium'' utilises [[photosynthesis]] for nitrogen fixation by carrying out the [[Mehler reaction]], during which the oxygen produced by PSII is reduced again after PSI. This regulation of photosynthesis for nitrogen fixation involves rapidly reversible coupling of their light-harvesting antenna, the [[phycobilisome]]s, with PSI and PSII.<ref name="Bergman et al.,2012">{{cite journal|author1=Bergman, B. |author2=Sandh, G. |author3=Lin, S. |author4=Larsson, H. |author5=Carpenter, E.J.  |name-list-style=amp |title=''Trichodesmium'' – a widespread marine cyanobacterium with unusual nitrogen fixation properties.|journal=FEMS Microbiology Reviews |volume=37 |issue=3 |year=2012|pages=1–17|doi=10.1111/j.1574-6976.2012.00352.x|pmid=22928644 |pmc=3655545}}</ref>

==Ecology==
[[File:Trichodesmium bloom, SW Pacific.jpg|thumb|upright=2.5|''Trichodesmium erythraeum'' bloom, between [[Vanuatu]] and [[New Caledonia]], SW Pacific Ocean.]]

[[File:Trichodesmium colonies sorted into the morphological classes.jpg|thumb|upright=2.5|right| {{center|Examples of ''Trichodesmium'' colonies sorted into morphological classes<br />(A) radial puffs, (B) non-radial puffs, (C) tufts.<ref>{{cite journal |doi = 10.3389/fmicb.2017.01122|title = Microbiome of Trichodesmium Colonies from the North Pacific Subtropical Gyre|year = 2017|last1 = Gradoville|first1 = Mary R.|last2 = Crump|first2 = Byron C.|last3 = Letelier|first3 = Ricardo M.|last4 = Church|first4 = Matthew J.|last5 = White|first5 = Angelicque E.|journal = Frontiers in Microbiology|volume = 8|page = 1122|pmid = 28729854|pmc = 5498550|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>}}]]

[[File:Trichodesmium interact with bacteria to acquire iron from dust.webp|thumb|upright=2.5|right| {{center|'''Colonies of marine cyanobacteria ''Trichodesmium''<br />interact with other bacteria to acquire iron from dust'''}} '''a.''' The N<sub>2</sub>-fixing ''Trichodesmium'' spp., which commonly occurs in tropical and sub-tropical waters, is of large environmental significance in fertilizing the ocean with important nutrients.<br />'''b.''' Trichodesmium can establish massive blooms in nutrient poor ocean regions with high dust deposition, partly due to their unique ability to capture dust, center it, and subsequently dissolve it.<br />'''c.''' Proposed dust-bound Fe acquisition pathway: Bacteria residing within the colonies produce [[siderophore]]s (C-I) that react with the dust particles in the colony core and generate dissolved Fe (C-II). This dissolved Fe, complexed by siderophores, is then acquired by both ''Trichodesmium'' and its resident bacteria (C-III), resulting in a mutual benefit to both partners of the [[Microbial consortium|consortium]].<ref>{{cite journal |doi = 10.1038/s42003-019-0534-z|title = Colonies of marine cyanobacteria Trichodesmium interact with associated bacteria to acquire iron from dust|year = 2019|last1 = Basu|first1 = Subhajit|last2 = Gledhill|first2 = Martha|last3 = De Beer|first3 = Dirk|last4 = Prabhu Matondkar|first4 = S. G.|last5 = Shaked|first5 = Yeala|journal = Communications Biology|volume = 2|page = 284|pmid = 31396564|pmc = 6677733}} [[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>]]

''Trichodesmium'' is found in oligotrophic waters, often when waters are calm and the mixed layer depth is shallow (around 100 m).<ref name="Capone et al., 1997">{{cite journal|author1=Capone D.G. |author2=Zehr J.P. |author3=Paerl H.W. |author4=Bergman B. |author5=Carpenter E.J. |year=1997|title=''Trichodesmium'', a globally significant marine cyanobacterium.|journal=Science|volume=276|issue=5316 |pages=1221–1229|doi=10.1126/science.276.5316.1221 |s2cid=53710858 }}</ref>
''Trichodesmium'' is found primarily in water between 20 and 34&nbsp;°C and is frequently encountered in tropical and sub-tropical oceans in western boundary currents.<ref name="Capone et al., 1997" /> Its presence is more pronounced in nitrogen poor water and can easily be seen when blooms form, trapping large ''Trichodesmium'' colonies at the surface.<ref name="Post, 2005">{{cite journal|author=Post, A.F.|year=2005|title=Nutrient limitation of marine cyanobacteria: Molecular ecology of nitrogen limitation in an oligotrophic sea|journal=Harmful Cyanobacteria|volume=3|editor1=Huisman J. |editor2=Matthijs H.C.P. |editor3=Visser P.M. |pages=87–108|doi=10.1007/1-4020-3022-3_5|series=Aquatic Ecology Series|isbn=978-1-4020-3009-3}}</ref>

As a [[diazotroph]], ''Trichodesmium'' contributes a large portion of the marine ecosystem's new nitrogen, estimated to produce between 60 and 80 Tg of nitrogen per year.<ref name="Bergman et al.,2012" /> Nitrogen fixed by ''Trichodesmium'' can either be used directly by the cell, enter the food chain through grazers, be released into dissolved pools, or get exported to the deep sea.<ref name="Zehr, 2008" /><!-- Deleted image removed: [[File:Trichodesmium nitrogen fixation.jpg|thumb|Nitrogen fixation and recycling in marine environments through ''Trichodesmium'' nitrogen fixation]] -->

Compared to eukaryotic phytoplankton, ''Trichodesmium'' has a slow growth rate, which has been hypothesized to be an adaptation to survival in high energy but low nutrient conditions of oligotrophic waters. Growth rate is limited by iron and phosphate concentrations in the water. In order to obtain these limiting nutrients, ''Trichodesmium'' is able to regulate buoyancy using its gas vacuole and move vertically throughout the water column, harvesting nutrients.<ref name="Capone et al., 1997" />

===Colonies===
Various species of ''Trichodesmium'' have been described based on morphology and structure of colonies formed. Colonies may consist of aggregates of several to several hundred trichomes and form fusiform (called "Tufts") colonies when aligned in parallel, or spherical (called "Puffs") colonies when aligned radially.<ref name="Siddiqui et al., 1991" /><!-- Deleted image removed: [[File:Trichodesmium-species.jpg|thumb|''Trichodesmium'' species forming fusiform and spherical colonies that are visible to the naked eye]] -->

''Trichodesmium'' colonies have been shown to have large degree of associations with other organisms, including bacteria, fungi, diatoms, copepods, tunicates, hydrozoans, and protozoans among other groups. These colonies may provide a source of shelter, buoyancy, and possibly food in the surface waters. Most of these associations appear to be commensal, with the ''Trichodesmium'' providing substrate and nutrition while deriving no obvious benefit from the organisms dwelling within the colonies.<ref name="O'Neil and Roman,1991">{{cite journal|author1=O'Neil J.M. |author2=Roman M.R. |year=1991|title=Grazers and associated organisms of ''Trichodesmium''|journal=Marine Pelagic Cyanobacteria: Trichodesmium and Other Diazotrophs|editor1=Carpenter E.J. |editor2=Capone D.G. |editor3=Rueter J.G. |pages=61–74}}</ref>

=== Sociality ===
''Trichodesmium'' are able to transfer between living as a single filament and as a colony. These different morphologies impact the way that the ''Trichodesmium'' interact with the environment. Switching between morphologies shows that there are different benefits and costs of existing in each form, and helps scientists understand why transferring from one form to another is necessary.<ref>{{Cite journal |last1=Eichner |first1=Meri |last2=Inomura |first2=Keisuke |last3=Pierella Karlusich |first3=Juan José |last4=Shaked |first4=Yeala |date=October 2023 |title=Better together? Lessons on sociality from Trichodesmium |journal=Trends in Microbiology |volume=31 |issue=10 |pages=1072–1084 |doi=10.1016/j.tim.2023.05.001 |pmid=37244772 |issn=0966-842X|doi-access=free }}</ref> Trichomes, or free-floating single filaments, have higher rates of nitrogen fixation as opposed to colonies.<ref>{{Cite journal |last1=Eichner |first1=Meri |last2=Thoms |first2=Silke |last3=Rost |first3=Björn |last4=Mohr |first4=Wiebke |last5=Ahmerkamp |first5=Soeren |last6=Ploug |first6=Helle |last7=Kuypers |first7=Marcel M. M. |last8=de Beer |first8=Dirk |date=April 2019 |title=N 2 fixation in free-floating filaments of Trichodesmium is higher than in transiently suboxic colony microenvironments |journal=New Phytologist |language=en |volume=222 |issue=2 |pages=852–863 |doi=10.1111/nph.15621 |issn=0028-646X |pmc=6590460 |pmid=30507001|bibcode=2019NewPh.222..852E }}</ref> When iron and phosphorus are limiting in the environment, the filamentous ''Trichodesmium'' are stimulated to aggregate together to form colonies.<ref>{{Cite journal |last1=Tzubari |first1=Yael |last2=Magnezi |first2=Liel |last3=Be'er |first3=Avraham |last4=Berman-Frank |first4=Ilana |date=June 2018 |title=Iron and phosphorus deprivation induce sociality in the marine bloom-forming cyanobacterium Trichodesmium |journal=The ISME Journal |volume=12 |issue=7 |pages=1682–1693 |doi=10.1038/s41396-018-0073-5 |issn=1751-7370 |pmc=6018766 |pmid=29463890|bibcode=2018ISMEJ..12.1682T }}</ref> Colonies can outcompete trichomes when environmental factors such as predation and rate of respiration for nutrient fixing are at play.<ref>{{Cite journal |last1=Agarwal |first1=Vitul |last2=Inomura |first2=Keisuke |last3=Mouw |first3=Colleen B. |date=2022-12-21 |editor-last=Veach |editor-first=Allison |title=Quantitative Analysis of the Trade-Offs of Colony Formation for Trichodesmium |journal=Microbiology Spectrum |language=en |volume=10 |issue=6 |pages=e0202522 |doi=10.1128/spectrum.02025-22 |issn=2165-0497 |pmc=9769814 |pmid=36374046}}</ref> The size of the colonies are also linked with the environmental oxygen content, due to the influence of oxygen in the process of photosynthesis.<ref>{{Cite journal |last1=Eichner |first1=Meri |last2=Basu |first2=Subhajit |last3=Wang |first3=Siyuan |last4=de Beer |first4=Dirk |last5=Shaked |first5=Yeala |date=June 2020 |title=Mineral iron dissolution in Trichodesmium colonies: The role of O 2 and pH microenvironments |url=https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lno.11377 |journal=Limnology and Oceanography |language=en |volume=65 |issue=6 |pages=1149–1160 |doi=10.1002/lno.11377 |bibcode=2020LimOc..65.1149E |issn=0024-3590|hdl=21.11116/0000-0005-F9DB-C |hdl-access=free }}</ref>

''Trichodesmium'' colonies are microbially diverse and are considered to be a holobiont, where multiple epibiont bacteria form a singular colony.<ref>{{Cite journal |last1=Rouco |first1=Mónica |last2=Haley |first2=Sheean T. |last3=Dyhrman |first3=Sonya T. |date=December 2016 |title=Microbial diversity within the T richodesmium holobiont |url=https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.13513 |journal=Environmental Microbiology |language=en |volume=18 |issue=12 |pages=5151–5160 |doi=10.1111/1462-2920.13513 |pmid=27581522 |bibcode=2016EnvMi..18.5151R |issn=1462-2912|url-access=subscription }}</ref> In these holobionts, ''Trichodesmium'' is the core host, but the microbial diversity of the holobiont colony is an essential part of its ecological interactions.<ref>{{cite journal |last1=Frischkorn |first1=Kyle R |last2=Rouco |first2=Mónica |last3=Van Mooy |first3=Benjamin A S |last4=Dyhrman |first4=Sonya T |title=Epibionts dominate metabolic functional potential of Trichodesmium colonies from the oligotrophic ocean |journal=The ISME Journal |date=1 September 2017 |volume=11 |issue=9 |pages=2090–2101 |doi=10.1038/ismej.2017.74|pmid=28534879 |pmc=5563961 |bibcode=2017ISMEJ..11.2090F |hdl=1912/9208 |hdl-access=free }}</ref> Some examples of the ''Trichodesmium'' microbiome’s epibiont bacteria include diazotrophs and several cyanobacteria species such as ''Richelia''.<ref>{{Cite journal |last1=Gradoville |first1=Mary R. |last2=Crump |first2=Byron C. |last3=Letelier |first3=Ricardo M. |last4=Church |first4=Matthew J. |last5=White |first5=Angelicque E. |date=2017 |title=Microbiome of Trichodesmium Colonies from the North Pacific Subtropical Gyre |journal=Frontiers in Microbiology |volume=8 |pages=1122 |doi=10.3389/fmicb.2017.01122 |doi-access=free |issn=1664-302X |pmc=5498550 |pmid=28729854}}</ref> ''Trichodesmium'' and the epibiont bacteria within the holobiont colonies may perform mutualistic interactions where limiting nutrients such as iron can be mobilized from dust.<ref>{{Cite journal |last1=Basu |first1=Subhajit |last2=Gledhill |first2=Martha |last3=de Beer |first3=Dirk |last4=Prabhu Matondkar |first4=S. G. |last5=Shaked |first5=Yeala |date=2019-08-02 |title=Colonies of marine cyanobacteria Trichodesmium interact with associated bacteria to acquire iron from dust |journal=Communications Biology |language=en |volume=2 |issue=1 |page=284 |doi=10.1038/s42003-019-0534-z |pmid=31396564 |pmc=6677733 |issn=2399-3642}}</ref> Other interactions with organisms arise when trichomes start to accumulate together. When colonies of ''Trichodesmium'' aggregate in large numbers, it is possible for them to produce a phycotoxin that can affect the growth other microorganisms in the local space of the ocean.<ref>{{Cite journal |last1=Bif |first1=Mariana Bernardi |last2=de Souza |first2=Márcio Silva |last3=Costa |first3=Luiza Dy Fonseca |last4=Yunes |first4=João Sarkis |date=2019 |title=Microplankton Community Composition Associated With Toxic Trichodesmium Aggregations in the Southwest Atlantic Ocean |journal=Frontiers in Marine Science |volume=6 |doi=10.3389/fmars.2019.00023 |doi-access=free |issn=2296-7745}}</ref>

===Blooms===
''Trichodesmium'' forms large, visible blooms in the surface waters. Blooms have been described in the Baltic Sea, the Red Sea, the Caribbean Sea, the Indian Ocean, the North and South Atlantic and the North Pacific, and off the coast of Australia.<ref name="Sellner,1991">{{cite journal|author=Sellner K.G.|year=1991|title=Trophodynamics of marine cyanobacteria blooms|journal=Marine Pelagic Cyanobacteria: Trichodesmium and Other Diazotrophs|editor1=Carpenter E.J. |editor2=Capone D.G. |editor3=Rueter J.G. |pages=75–94}}</ref> One of the earliest blooms was described by E. Dupont in the Red Sea, noticed for turning the surface of the water a reddish color. This bloom was said to extend about 256 nautical miles. Most blooms are several kilometers long and last one to several months. Blooms can form in coastal or oceanic waters, most frequently when the water has been still for some time and surface temperatures exceed 27&nbsp;°C.<ref name="Carpenter and Capone, 1991">{{cite journal|author1=Carpenter E.J. |author2=Capone D.G. |year=1991|title=Nitrogen fixation in ''Trichodesmium'' blooms|journal=Marine Pelagic Cyanobacteria: Trichodesmium and Other Diazotrophs|editor1=Carpenter E.J. |editor2=Capone D.G. |editor3=Rueter J.G. |pages=75–94}}</ref>

''Trichodesmium'' blooms release carbon, nitrogen and other nutrients into the environment. Some species of ''Trichodesmium'' have been shown to release toxins which cause mortalities in some copepods, fish, and oysters. Blooms have also been credited with releasing the toxin which causes clupeotoxism in humans after ingesting fish which have bioaccumulated the toxin during ''Trichodesmium'' blooms. The larger impact of these blooms is likely important to the oceanic ecosystem and is the source of many studies.<ref name="Bergman et al.,2012" /> Blooms are traced and tracked using satellite imaging where the highly reflective gas vacuole makes ''Trichodesmium'' blooms easily detectable.<ref name="Zehr and Paerl,2008">{{cite book|author1=Zehr J.P. |author2=Paerl H.W. |year=2008|chapter=Molecular ecological aspects of nitrogen fixation in the marine environment|title=Microbial Ecology of the Oceans|pages=481–525 |edition=2nd|editor=Kirchman D.L.|doi=10.1002/9780470281840.ch13 |isbn=9780470281840 }}</ref>

It is expected that blooms may increase due to [[Human impact on the environment|anthropogenic effects]] in the coming years. Phosphate loading of the environment (through fertilizer pollution, waste disposal, and mariculture) will reduce the growth constraints associated with limited phosphate and likely increase bloom occurrences.<ref name="Post, 2005" /> Likewise, global warming is projected to increase stratification and cause a shallowing of the mixed layer depth. Both of these factors are associated with ''Trichodesmium'' blooms and may also cause an increase in the occurrence of blooms in the future.<ref name="Bergman et al.,2012" />

==References==
{{Reflist}}

==Bibliography==
* Kana, T.M. (1993) Rapid oxygen cycling in ''Trichodesmium thiebautii''. ''Limnology and Oceanography'' '''38''': 18–24.
* Berman-Frank, I., Lundgren, P., Chen, Y.-B., Küpper, H., Kolber, Z., Bergman, B., and Falkowski, P. (2001) Segregation of nitrogen fixation and oxygenic photosynthesis in the marine cyanobacterium ''Trichodesmium''. ''Science'' '''294''': 1534–1537.
* Küpper, H., Ferimazova, N., Šetlík, I., and Berman-Frank, I. (2004) Traffic lights in ''Trichodesmium'': regulation of photosynthesis for nitrogen fixation studied by chlorophyll fluorescence kinetic microscopy. ''Plant Physiology'' '''135''': 2120–2133.

==External links==
{{Wikispecies}}
*[http://dornsife.usc.edu/labs/capone/publications Publications on ''Trichodesmium'' from a Marine Biogeochemistry laboratory at the University of Southern California] {{Webarchive|url=https://web.archive.org/web/20121126120348/http://dornsife.usc.edu/labs/capone/publications/ |date=2012-11-26 }}
*[http://charles-darwin.classic-literature.co.uk/the-voyage-of-the-beagle/ebook-page-08.asp Charles Darwin's description of sailing through a ''Trichodesmium'' bloom]
*[https://web.archive.org/web/20060506003914/http://research.myfwc.com/features/view_article.asp?id=22896 Trichodesmium in Florida — 2004], Florida Fish and Wildlife Conservation Commission [https://web.archive.org/web/20061004154055/http://research.myfwc.com/ Fish and Wildlife Research Institute] <!-- on the name "sea sawdust" -->

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[[Category:Cyanobacteria genera]]
[[Category:Oscillatoriales]]