Editing Phytoplankton

{{short description| Autotrophic members of the plankton ecosystem }}
{{Use dmy dates|date=February 2021}}
{{plankton sidebar|trophic}}

'''Phytoplankton''' ({{IPAc-en|ˌ|f|aɪ|t|oʊ|ˈ|p|l|æ|ŋ|k|t|ə|n}}) are the [[autotroph]]ic (self-feeding) components of the [[plankton]] community and a key part of ocean and freshwater [[Aquatic ecosystem|ecosystems]]. The name comes from the [[Greek language|Greek]] words {{Lang|grc|φυτόν}} ({{Lang|grc-latn|phyton}}), meaning '[[plant]]', and {{Lang|grc|πλαγκτός}} ({{Lang|grc-latn|planktos}}), meaning 'wanderer' or 'drifter'.<ref>{{cite book |last=Thurman |first=H. V. |year=2007 |title=Introductory Oceanography |publisher=Academic Internet Publishers |isbn=978-1-4288-3314-2}}{{page needed|date=February 2016}}</ref><ref name=":0">{{Cite journal |last1=Pierella Karlusich |first1=Juan José |last2=Ibarbalz |first2=Federico M. |last3=Bowler |first3=Chris |date=2020-01-03 |title=Phytoplankton in the Tara Ocean |journal=Annual Review of Marine Science |volume=12 |issue=1 |pages=233–265 |doi=10.1146/annurev-marine-010419-010706 |pmid=31899671 |bibcode=2020ARMS...12..233P |s2cid=209748051 |issn=1941-1405 |doi-access=free}}</ref><ref name=":1">{{Cite journal |last1=Pierella Karlusich |first1=Juan José |last2=Ibarbalz |first2=Federico M |last3=Bowler |first3=Chris |title=Exploration of marine phytoplankton: from their historical appreciation to the omics era |journal=Journal of Plankton Research |year=2020 |volume=42 |pages=595–612 |doi=10.1093/plankt/fbaa049 |doi-access=free |hdl=11336/143676 |hdl-access=free}}</ref>

Phytoplankton obtain their energy through [[photosynthesis]], as trees and other plants do on land. This means phytoplankton must have light from the sun, so they live in the well-lit surface layers ([[euphotic zone]]) of oceans and lakes. In comparison with terrestrial plants, phytoplankton are distributed over a larger surface area, are exposed to less seasonal variation and have markedly faster turnover rates than trees (days versus decades). As a result, phytoplankton respond rapidly on a global scale to climate variations.

Phytoplankton form the base of marine and freshwater food webs and are key players in the global [[carbon cycle]]. They account for about half of global photosynthetic activity and at least half of the oxygen production, despite amounting to only about 1% of the global plant biomass. 

Phytoplankton are very diverse, comprising photosynthesizing bacteria ([[cyanobacteria]]) and various unicellular [[protist]] groups (notably the [[Diatom|diatoms]]). 

Most phytoplankton are too small to be individually seen with the [[naked eye|unaided eye]]. However, when present in high enough numbers, some varieties may be noticeable as colored patches on the water surface due to the presence of [[chlorophyll]] within their cells and accessory pigments (such as [[phycobiliprotein]]s or [[xanthophyll]]s) in some species.

==Types==
Phytoplankton are [[photosynthesizing]] microscopic protists and bacteria that inhabit the upper sunlit layer of marine and fresh water bodies of water on Earth. Paralleling plants on land, phytoplankton undertake [[Marine primary production|primary production]] in water,<ref name=":0" /> creating [[organic compound]]s from [[carbon dioxide]] dissolved in the water. Phytoplankton form the base of — and sustain — the aquatic [[food web]],<ref>{{cite web |last=Ghosal; Rogers; Wray |first=S.; M.; A. |title=The Effects of Turbulence on Phytoplankton |url=https://ntrs.nasa.gov/search.jsp?R=20040171754&qs=Ntx%3Dmode%2520matchany%26Ntk%3DTitle%26Ns%3DLoaded-Date |work=Aerospace Technology Enterprise |publisher=NTRS |access-date=16 June 2011}}</ref> and are crucial players in the Earth's [[carbon cycle]].<ref name=NASA2015 />

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| image1            = Diatoms through the microscope.jpg
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| caption1          = [[Diatom]]s are one of the most common types<br />of phytoplankton
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| caption2          = A [[cyanobacteria]] species (''Cylindrospermum'' sp)
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Phytoplankton are very diverse, comprising photosynthesizing bacteria ([[cyanobacteria]]) and various unicellular [[protist]] groups (notably the [[Diatom|diatoms]]). Many other organism groups formally named as phytoplankton, including [[Coccolithophore|coccolithophores]] and [[Dinoflagellate|dinoflagellates]], are now no longer included as they are not only [[Photoautotrophism|phototrophic]] but can also eat.<ref>{{Cite journal |last1=Mitra |first1=Aditee |last2=Caron |first2=David A. |last3=Faure |first3=Emile |last4=Flynn |first4=Kevin J. |last5=Leles |first5=Suzana Gonçalves |last6=Hansen |first6=Per J. |last7=McManus |first7=George B. |last8=Not |first8=Fabrice |last9=do Rosario Gomes |first9=Helga |last10=Santoferrara |first10=Luciana F. |last11=Stoecker |first11=Diane K. |last12=Tillmann |first12=Urban |date=27 February 2023 |title=The Mixoplankton Database (MDB): Diversity of photo-phago-trophic plankton in form, function, and distribution across the global ocean |url=https://onlinelibrary.wiley.com/doi/10.1111/jeu.12972 |journal=Journal of Eukaryotic Microbiology |language=en |volume=70 |issue=4 |pages=e12972 |doi=10.1111/jeu.12972 |pmid=36847544 |issn=1066-5234}}</ref> These organisms are now more correctly termed [[mixoplankton]].<ref>{{Cite journal |last1=Flynn |first1=Kevin J |last2=Mitra |first2=Aditee |last3=Anestis |first3=Konstantinos |last4=Anschütz |first4=Anna A |last5=Calbet |first5=Albert |last6=Ferreira |first6=Guilherme Duarte |last7=Gypens |first7=Nathalie |last8=Hansen |first8=Per J |last9=John |first9=Uwe |last10=Martin |first10=Jon Lapeyra |last11=Mansour |first11=Joost S |last12=Maselli |first12=Maira |last13=Medić |first13=Nikola |last14=Norlin |first14=Andreas |last15=Not |first15=Fabrice |date=2019-07-26 |title=Mixotrophic protists and a new paradigm for marine ecology: where does plankton research go now? |url=https://academic.oup.com/plankt/article/41/4/375/5531601 |journal=Journal of Plankton Research |language=en |volume=41 |issue=4 |pages=375–391 |doi=10.1093/plankt/fbz026 |issn=0142-7873|hdl=10261/192145 |hdl-access=free }}</ref> This recognition has important consequences for how we view the functioning of the planktonic food web.<ref>{{Cite journal |last1=Glibert |first1=Patricia M. |last2=Mitra |first2=Aditee |date=2022-01-21 |title=From webs, loops, shunts, and pumps to microbial multitasking: Evolving concepts of marine microbial ecology, the mixoplankton paradigm, and implications for a future ocean |url=http://dx.doi.org/10.1002/lno.12018 |journal=Limnology and Oceanography |volume=67 |issue=3 |pages=585–597 |doi=10.1002/lno.12018 |bibcode=2022LimOc..67..585G |issn=0024-3590}}</ref>

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== Ecology ==
[[File:Global phytoplankton distribution - NASA.webm|thumb|upright=1.8| {{center|'''Global distribution of ocean phytoplankton – NASA'''}}
This visualization shows a model simulation of the dominant phytoplankton types averaged over the period 1994–1998.
* Red = [[diatom]]s (big phytoplankton, which need silica)
* Yellow = [[flagellate]]s (other big phytoplankton)
* Green = [[prochlorococcus]] (small phytoplankton that cannot use nitrate)
* Cyan = [[synechococcus]] (other small phytoplankton)
Opacity indicates concentration of the carbon biomass. In particular, the role of the swirls and filaments (mesoscale features) appear important in maintaining high biodiversity in the ocean.<ref name=NASA2015>[https://svs.gsfc.nasa.gov/30669 Modeled Phytoplankton Communities in the Global Ocean] ''NASA Hyperwall'', 30 September 2015. {{PD-notice}}</ref><ref>{{Cite web |title=MIT Darwin Project |url=https://darwinproject.mit.edu/ |publisher=[[Massachusetts Institute of Technology]] |language=en-US}}</ref>]]

Phytoplankton obtain [[energy]] through the [[Biological process|process]] of [[photosynthesis]] and must therefore live in the well-lit surface layer (termed the [[Photic zone|euphotic zone]]) of an [[ocean]], [[sea]], [[lake]], or other body of water. Phytoplankton account for about half of all [[Photosynthesis|photosynthetic activity]] on Earth.<ref>{{cite journal |author1=Michael J. Behrenfeld |display-authors=etal |title=Biospheric primary production during an ENSO transition |journal=Science |date=2001-03-30 |volume=291 |issue=5513 |pages=2594–7 |doi=10.1126/science.1055071 |pmid=11283369 |url=https://escholarship.org/content/qt51z7z4n6/qt51z7z4n6.pdf?t=nuq67b |bibcode=2001Sci...291.2594B |s2cid=38043167}}</ref><ref>[http://www.nasa.gov/topics/earth/features/modis_fluorescence.html "NASA Satellite Detects Red Glow to Map Global Ocean Plant Health"] {{Webarchive|url=https://web.archive.org/web/20210410144820/https://www.nasa.gov/topics/earth/features/modis_fluorescence.html |date=10 April 2021 }} [[NASA]], 28 May 2009.</ref><ref>{{Cite web |url=http://www.nasa.gov/centers/goddard/news/topstory/chlorophyll.html |title=Satellite Sees Ocean Plants Increase, Coasts Greening |access-date=9 June 2014 |publisher=[[NASA]] |date=2 March 2005 |archive-date=29 October 2011 |archive-url=https://web.archive.org/web/20111029124533/http://www.nasa.gov/centers/goddard/news/topstory/chlorophyll.html |url-status=dead }}</ref> Their cumulative energy fixation in [[carbon compounds]] ([[primary production]]) is the basis for the vast majority of oceanic and also many [[freshwater]] [[food web]]s ([[chemosynthesis]] is a notable exception).

While almost all phytoplankton [[species]] are [[obligate]] [[photoautotroph]]s, there are some that are [[mixotroph]]ic and other, non-pigmented [[species]] that are actually [[heterotroph]]ic (the latter are often viewed as [[zooplankton]]).<ref name=":0" /><ref>{{Cite journal |date=2016-04-01 |title=Defining Planktonic Protist Functional Groups on Mechanisms for Energy and Nutrient Acquisition: Incorporation of Diverse Mixotrophic |journal=Protist |language=en |volume=167 |issue=2 |pages=106–120 |doi=10.1016/j.protis.2016.01.003 |issn=1434-4610 |last1=Mitra |first1=Aditee |last2=Flynn |first2=Kevin J. |last3=Tillmann |first3=Urban |last4=Raven |first4=John A. |last5=Caron |first5=David |last6=Stoecker |first6=Diane K. |last7=Not |first7=Fabrice |last8=Hansen |first8=Per J. |last9=Hallegraeff |first9=Gustaaf |last10=Sanders |first10=Robert |last11=Wilken |first11=Susanne |last12=McManus |first12=George |last13=Johnson |first13=Mathew |last14=Pitta |first14=Paraskevi |last15=Våge |first15=Selina |last16=Berge |first16=Terje |last17=Calbet |first17=Albert |last18=Thingstad |first18=Frede |last19=Jeong |first19=Hae Jin |last20=Burkholder |first20=Joann |last21=Glibert |first21=Patricia M. |author-link21=Patricia Glibert |last22=Granéli |first22=Edna |last23=Lundgren |first23=Veronica |pmid=26927496 |doi-access=free |hdl=10261/131722 |hdl-access=free}}</ref> Of these, the best known are [[dinoflagellate]] [[genus|genera]] such as ''[[Noctiluca]]'' and ''[[Dinophyceae|Dinophysis]]'', that obtain [[organic matter|organic]] [[carbon]] by [[ingestion|ingesting]] other organisms or [[Detritus|detrital]] material.

Phytoplankton live in the [[photic zone]] of the ocean, where [[photosynthesis]] is possible. During photosynthesis, they assimilate carbon dioxide and release oxygen. If solar radiation is too high, phytoplankton may fall victim to [[photodegradation]]. Phytoplankton species feature a large variety of photosynthetic [[pigment]]s which species-specifically enables them to absorb different [[Photosynthetically active radiation|wavelengths]] of the variable underwater light.<ref>{{Cite book|last=Kirk|first=John T. O.|url=https://www.cambridge.org/core/books/light-and-photosynthesis-in-aquatic-ecosystems/C19B28AE07B1CDEBDA5593194DE4E304|title=Light and Photosynthesis in Aquatic Ecosystems|date=1994|publisher=Cambridge University Press|edition=2|location=Cambridge|doi=10.1017/cbo9780511623370|isbn=9780511623370}}</ref> This implies different species can use the wavelength of light different efficiently and the light is not a single [[Resource (biology)|ecological resource]] but a multitude of resources depending on its spectral composition.<ref>{{Cite journal|last1=Stomp|first1=Maayke|last2=Huisman|first2=Jef|last3=de Jongh|first3=Floris|last4=Veraart|first4=Annelies J.|last5=Gerla|first5=Daan|last6=Rijkeboer|first6=Machteld|last7=Ibelings|first7=Bas W.|last8=Wollenzien|first8=Ute I. A.|last9=Stal|first9=Lucas J.|date=November 2004|title=Adaptive divergence in pigment composition promotes phytoplankton biodiversity|url=https://www.nature.com/articles/nature03044|journal=Nature|language=en|volume=432|issue=7013|pages=104–107|doi=10.1038/nature03044|pmid=15475947|bibcode=2004Natur.432..104S|s2cid=4409758|issn=1476-4687}}</ref> By that it was found that changes in the spectrum of light alone can alter natural phytoplankton communities even if the same [[Luminous intensity|intensity]] is available.<ref>{{Cite journal|last1=Hintz|first1=Nils Hendrik|last2=Zeising|first2=Moritz|last3=Striebel|first3=Maren|date=2021|title=Changes in spectral quality of underwater light alter phytoplankton community composition|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11882|journal=Limnology and Oceanography|language=en|volume=66|issue=9|pages=3327–3337|doi=10.1002/lno.11882|bibcode=2021LimOc..66.3327H|s2cid=237849374|issn=1939-5590}}</ref> For growth, phytoplankton cells additionally depend on nutrients, which enter the ocean by rivers, continental weathering, and glacial ice meltwater on the poles. Phytoplankton release [[dissolved organic carbon]] (DOC) into the ocean. Since phytoplankton are the basis of [[marine food web]]s, they serve as prey for [[zooplankton]], [[fish larvae]] and other [[heterotroph]]ic organisms. They can also be degraded by bacteria or by [[viral lysis]]. Although some phytoplankton cells, such as [[dinoflagellate]]s, are able to migrate vertically, they are still incapable of actively moving against currents, so they slowly sink and ultimately fertilize the seafloor with dead cells and [[detritus]].<ref name=Käse2018 />

[[File:Cycling of marine phytoplankton.png|thumb|left|upright=1.8|{{center|Cycling of marine phytoplankton{{hsp}}<ref name=Käse2018>Käse L, Geuer JK. (2018) [https://link.springer.com/chapter/10.1007/978-3-319-93284-2_5 "Phytoplankton responses to marine climate change–an introduction"]. In Jungblut S., Liebich V., Bode M. (Eds) ''YOUMARES 8–Oceans Across Boundaries: Learning from each other'', pages 55–72, Springer. {{doi|10.1007/978-3-319-93284-2_5}}. [[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>}}]]

Phytoplankton are crucially dependent on a number of [[nutrient]]s. These are primarily [[macronutrient (ecology)|macronutrients]] such as [[nitrate]], [[phosphate]] or [[silicic acid]], which are required in relatively large quantities for growth. Their availability in the surface ocean is governed by the balance between the so-called [[biological pump]] and [[upwelling]] of deep, nutrient-rich waters. The [[stoichiometry|stoichiometric]] nutrient composition of phytoplankton drives — and is driven by — the [[Redfield ratio]] of macronutrients generally available throughout the surface oceans. Phytoplankton also rely on trace metals such as iron (Fe), manganese (Mn), zinc (Zn), cobalt (Co), cadmium (Cd) and copper (Cu) as essential micronutrients, influencing their growth and community composition.<ref>{{Cite journal |last=Sunda |first=William |date=2012-06-07 |title=Feedback Interactions between Trace Metal Nutrients and Phytoplankton in the Ocean |journal=Frontiers in Microbiology |language=English |volume=3 |page=204 |doi=10.3389/fmicb.2012.00204 |doi-access=free |issn=1664-302X |pmc=3369199 |pmid=22701115}}</ref> Limitations in these metals can lead to co-limitations and shifts in phytoplankton community structure.<ref>{{Cite journal |last1=Browning |first1=Thomas J. |last2=Moore |first2=C. Mark |date=2023-08-17 |title=Global analysis of ocean phytoplankton nutrient limitation reveals high prevalence of co-limitation |journal=Nature Communications |language=en |volume=14 |issue=1 |pages=5014 |doi=10.1038/s41467-023-40774-0 |issn=2041-1723 |pmc=10435517 |pmid=37591895|bibcode=2023NatCo..14.5014B }}</ref><ref>{{Cite journal |last1=Moore |first1=C. M. |last2=Mills |first2=M. M. |last3=Arrigo |first3=K. R. |last4=Berman-Frank |first4=I. |last5=Bopp |first5=L. |last6=Boyd |first6=P. W. |last7=Galbraith |first7=E. D. |last8=Geider |first8=R. J. |last9=Guieu |first9=C. |last10=Jaccard |first10=S. L. |last11=Jickells |first11=T. D. |last12=La Roche |first12=J. |last13=Lenton |first13=T. M. |last14=Mahowald |first14=N. M. |last15=Marañón |first15=E. |date=September 2013 |title=Processes and patterns of oceanic nutrient limitation |url=https://www.nature.com/articles/ngeo1765 |journal=Nature Geoscience |language=en |volume=6 |issue=9 |pages=701–710 |doi=10.1038/ngeo1765 |bibcode=2013NatGe...6..701M |issn=1752-0908}}</ref> Across large areas of the oceans such as the [[Southern Ocean]], phytoplankton are often limited by the lack of the [[micronutrient]] [[iron]]. <ref>{{Cite journal |last1=Tagliabue |first1=Alessandro |last2=Bowie |first2=Andrew R. |last3=Boyd |first3=Philip W. |last4=Buck |first4=Kristen N. |last5=Johnson |first5=Kenneth S. |last6=Saito |first6=Mak A. |date=March 2017 |title=The integral role of iron in ocean biogeochemistry |url=https://www.nature.com/articles/nature21058 |journal=Nature |language=en |volume=543 |issue=7643 |pages=51–59 |doi=10.1038/nature21058 |pmid=28252066 |bibcode=2017Natur.543...51T |issn=1476-4687}}</ref> This has led to some scientists advocating [[iron fertilization]] as a means to counteract the accumulation of [[Human impact on the environment|human-produced]] carbon dioxide (CO<sub>2</sub>) in the [[atmosphere]].<ref name=richtel07>{{Cite news |first=M. |last=Richtel |title=Recruiting Plankton to Fight Global Warming |newspaper=The New York Times |date=1 May 2007 |url=https://www.nytimes.com/2007/05/01/business/01plankton.html }}</ref> Large-scale experiments have added iron (usually as salts such as [[ferrous sulfate]]) to the oceans to promote phytoplankton growth and draw [[Carbon dioxide in Earth's atmosphere|atmospheric CO<sub>2</sub>]] into the ocean. Controversy about manipulating the ecosystem and the efficiency of iron fertilization has slowed such experiments.<ref>{{cite journal |last1=Monastersky |first1=Richard |title=Iron versus the Greenhouse: Oceanographers Cautiously Explore a Global Warming Therapy |journal=Science News |volume=148 |issue=14 |year=1995 |pages=220–1 |doi=10.2307/4018225|jstor=4018225 }}</ref><ref>{{Cite journal |last1=Buesseler |first1=Ken O. |last2=Bianchi |first2=Daniele |last3=Chai |first3=Fei |last4=Cullen |first4=Jay T. |last5=Estapa |first5=Margaret |last6=Hawco |first6=Nicholas |last7=John |first7=Seth |last8=McGillicuddy |first8=Dennis J. |last9=Morris |first9=Paul J. |last10=Nawaz |first10=Sara |last11=Nishioka |first11=Jun |last12=Pham |first12=Anh |last13=Ramakrishna |first13=Kilaparti |last14=Siegel |first14=David A. |last15=Smith |first15=Sarah R. |date=2024-09-09 |title=Next steps for assessing ocean iron fertilization for marine carbon dioxide removal |journal=Frontiers in Climate |language=English |volume=6 |doi=10.3389/fclim.2024.1430957 |doi-access=free |issn=2624-9553}}</ref> The ocean science community still has a divided attitude toward the study of iron fertilization as a potential marine Carbon Dioxide Removal (mCDR) approach.<ref>{{Cite web |last=Luhn |first=Alec |title=Scientists Will Engineer the Ocean to Absorb More Carbon Dioxide |url=https://www.scientificamerican.com/article/scientists-will-engineer-the-ocean-to-absorb-more-carbon-dioxide/ |access-date=2024-10-21 |website=Scientific American |language=en}}</ref><ref>{{Cite journal |last1=Cullen |first1=John J. |last2=Boyd |first2=Philip W. |date=2008-07-29 |title=Predicting and verifying the intended and unintended consequences of large-scale ocean iron fertilization |url=https://www.int-res.com/abstracts/meps/v364/p295-301/ |journal=Marine Ecology Progress Series |language=en |volume=364 |pages=295–301 |doi=10.3354/meps07551 |bibcode=2008MEPS..364..295C |issn=0171-8630}}</ref>

Phytoplankton depend on [[B vitamins]] for survival. Areas in the ocean have been identified as having a major lack of some B Vitamins, and correspondingly, phytoplankton.<ref>{{cite web |url=https://www.sciencedaily.com/releases/2012/07/120723162613.htm |title=Existence of vitamin 'deserts' in the ocean confirmed|work=ScienceDaily|first=Sergio|last=Sañudo-Wilhelmy|date=2012-06-23}}</ref>

The effects of [[anthropogenic warming]] on the global population of phytoplankton is an area of active research. Changes in the vertical stratification of the water column, the rate of temperature-dependent biological reactions, and the atmospheric supply of nutrients are expected to have important effects on future phytoplankton productivity.<ref name="ReferenceA">{{cite journal|last1=Henson|first1=S. A.|last2=Sarmiento|first2=J. L.|last3=Dunne|first3=J. P.|last4=Bopp|first4=L.|last5=Lima|first5=I.|last6=Doney|first6=S. C.|author-link6=Scott Doney|last7=John|first7=J.|last8=Beaulieu|first8=C.|year=2010|title=Detection of anthropogenic climate change in satellite records of ocean chlorophyll and productivity|journal=Biogeosciences|volume=7|issue=2|pages=621–40|doi=10.5194/bg-7-621-2010|bibcode=2010BGeo....7..621H|doi-access=free|hdl=1912/3208|hdl-access=free}}</ref><ref name="ReferenceB">{{cite journal|last1=Steinacher|first1=M.|last2=Joos|first2=F.|last3=Frölicher|first3=T. L.|last4=Bopp|first4=L.|last5=Cadule|first5=P.|last6=Cocco|first6=V.|last7=Doney|first7=S. C.|last8=Gehlen|first8=M.|last9=Lindsay|first9=K.|year=2010|title=Projected 21st century decrease in marine productivity: a multi-model analysis|journal=Biogeosciences|volume=7|issue=3|pages=979–1005|doi=10.5194/bg-7-979-2010|last10=Moore|first10=J. K.|last11=Schneider|first11=B.|last12=Segschneider|first12=J.|bibcode=2010BGeo....7..979S|doi-access=free|hdl=11858/00-001M-0000-0011-F69E-5|hdl-access=free}}</ref>

[[File:Luminescent beaches in Chabahar3.jpg|thumb| [[Bioluminescence]] in phytoplankton triggered by the agitation of waves crashing on a beach]]

The effects of anthropogenic ocean acidification on phytoplankton growth and community structure has also received considerable attention. The cells of coccolithophore phytoplankton are typically covered in a calcium carbonate shell called a [[Coccolithophore#Coccolithophore shells|coccosphere]] that is sensitive to ocean acidification. Because of their short generation times, evidence suggests some phytoplankton can adapt to changes in pH induced by increased carbon dioxide on rapid time-scales (months to years).<ref>{{Cite journal|last1=Collins|first1=Sinéad|last2=Rost|first2=Björn|last3=Rynearson|first3=Tatiana A.|author-link3=Tatiana Rynearson|date=2013-11-25|title=Evolutionary potential of marine phytoplankton under ocean acidification|journal=Evolutionary Applications|language=en|volume=7|issue=1|pages=140–155|doi=10.1111/eva.12120|issn=1752-4571|pmc=3894903|pmid=24454553}}</ref><ref>{{Cite journal|last1=Lohbeck|first1=Kai T.|last2=Riebesell|first2=Ulf|last3=Reusch|first3=Thorsten B. H.|date=2012-04-08|title=Adaptive evolution of a key phytoplankton species to ocean acidification|journal=Nature Geoscience|language=En|volume=5|issue=5|pages=346–351|doi=10.1038/ngeo1441|issn=1752-0894|bibcode=2012NatGe...5..346L}}</ref>

Phytoplankton serve as the base of the aquatic food web, providing an essential ecological function for all aquatic life. Under future conditions of anthropogenic warming and ocean acidification, changes in phytoplankton mortality due to changes in rates of [[zooplankton]] grazing may be significant.<ref name=Cavicchioli2019 /> One of the many [[food chain]]s in the ocean – remarkable due to the small number of links – is that of phytoplankton sustaining [[krill]] (a [[crustacean]] similar to a tiny shrimp), which in turn sustain [[baleen whale]]s.

The El Niño-Southern Oscillation (ENSO) cycles in the Equatorial Pacific area can affect phytoplankton.<ref name="Large-scale shifts in phytoplankton">{{cite journal |last1=Masotti |first1=I. |last2=Moulin |first2=C. |last3=Alvain |first3=S. |last4=Bopp |first4=L. |last5=Tagliabue |first5=A. |last6=Antoine |first6=D. |title=Large-scale shifts in phytoplankton groups in the Equatorial Pacific during ENSO cycles |journal=Biogeosciences |date=4 March 2011 |volume=8 |issue=3 |pages=539–550 |doi=10.5194/bg-8-539-2011|bibcode=2011BGeo....8..539M |hdl=20.500.11937/40912 |hdl-access=free |doi-access=free }}</ref> Biochemical and physical changes during ENSO cycles modify the phytoplankton community structure.<ref name="Large-scale shifts in phytoplankton"/> Also, changes in the structure of the phytoplankton, such as a significant reduction in biomass and phytoplankton density, particularly during El Nino phases can occur.<ref>{{cite journal |first1=María Belén |last1=Sathicqab |first2=Delia Elena |last2=Bauerac |first3=Nora |last3=Gómez |title=Influence of El Niño Southern Oscillation phenomenon on coastal phytoplankton in a mixohaline ecosystem on the southeastern of South America: Río de la Plata estuary |journal=Marine Pollution Bulletin |volume=98 |issue=1–2 |date=15 September 2015 |pages=26–33 |doi=10.1016/j.marpolbul.2015.07.017|pmid=26183307 |bibcode=2015MarPB..98...26S |url=http://sedici.unlp.edu.ar/handle/10915/151797 |hdl=11336/112961 |hdl-access=free }}</ref> The sensitivity of phytoplankton to environmental changes is why they are often used as indicators of estuarine and coastal ecological condition and health.<ref>{{cite journal |title=Influence of El Niño Southern Oscillation phenomenon on coastal phytoplankton in a mixohaline ecosystem on the southeastern of South America: Río de la Plata estuary |journal=Marine Pollution Bulletin |date=15 September 2015 |volume=98 |issue=1–2 |pages=26–33 |doi=10.1016/j.marpolbul.2015.07.017|last1=Sathicq |first1=María Belén |last2=Bauer |first2=Delia Elena |last3=Gómez |first3=Nora |pmid=26183307 |bibcode=2015MarPB..98...26S |url=http://sedici.unlp.edu.ar/handle/10915/151797 |hdl=11336/112961 |hdl-access=free }}</ref> To study these events satellite ocean color observations are used to observe these changes. Satellite images help to have a better view of their global distribution.<ref name="Large-scale shifts in phytoplankton"/>

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==Diversity==
{{multiple image
| align             = right
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| header            = 
| image1            = Spring Bloom Colors the Pacific Near Hokkaido.jpg
| alt1              = 
| caption1          = When two currents collide (here the [[Oyashio Current|Oyashio]] and [[Kuroshio Current|Kuroshio]] currents) they create [[eddies]]. Phytoplankton concentrates along the boundaries of the eddies, tracing the motion of the water.
| image2            = Cwall99 lg.jpg
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| caption2          = [[Algal bloom]] off south west England
| image3            = NASA satellite view of Southern Ocean phytoplankton bloom (crop).jpg
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| caption3          = NASA satellite view of Southern Ocean phytoplankton bloom
}}

The term phytoplankton encompasses all photoautotrophic microorganisms in aquatic [[food web]]s. However, unlike terrestrial [[communities]], where most autotrophs are [[plant]]s, phytoplankton are a diverse group, incorporating [[protist]]an [[eukaryote]]s and both [[Bacteria|eubacterial]] and [[archaebacteria]]l [[prokaryote]]s. There are about 5,000 known species of marine phytoplankton.<ref name="Hallegraeff 03">{{cite book|title=Manual on Harmful Marine Microalgae|last=Hallegraeff|first=G.M.|publisher=Unesco|year=2003|isbn=978-92-3-103871-6|editor-last1=Hallegraeff|editor-first1=Gustaaf M.|pages=25–49|chapter=Harmful algal blooms: a global overview|editor-last2=Anderson|editor-first2=Donald Mark|editor-last3=Cembella|editor-first3=Allan D.|editor-last4=Enevoldsen|editor-first4=Henrik O.|chapter-url=http://unesdoc.unesco.org/images/0013/001317/131711e.pdf}}</ref> How such diversity [[evolution|evolved]] despite scarce resources (restricting [[niche differentiation]]) is unclear.<ref>{{cite journal|last1=Hutchinson|first1=G. E.|year=1961|title=The Paradox of the Plankton|journal=The American Naturalist|volume=95|issue=882|pages=137–45|doi=10.1086/282171|s2cid=86353285}}</ref>

In terms of numbers, the most important groups of phytoplankton include the [[diatom]]s, [[cyanobacteria]] and [[dinoflagellate]]s, although many other groups of [[algae]] are represented. One group, the [[coccolithophore|coccolithophorids]], is responsible (in part) for the release of significant amounts of [[dimethyl sulfide]] (DMS) into the [[Earth's atmosphere|atmosphere]]. DMS is [[Redox|oxidized]] to form sulfate which, in areas where ambient [[aerosol]] particle concentrations are low, can contribute to the population of [[cloud condensation nuclei]], mostly leading to increased cloud cover and cloud [[albedo]] according to the so-called [[CLAW hypothesis]].<ref name="Oceanicphytoplankton">{{cite journal|last1=Charlson|first1=Robert J.|last2=Lovelock|first2=James E.|last3=Andreae|first3=Meinrat O.|last4=Warren|first4=Stephen G.|year=1987|title=Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate|journal=Nature|volume=326|issue=6114|pages=655–61|bibcode=1987Natur.326..655C|doi=10.1038/326655a0|s2cid=4321239}}</ref><ref>{{cite journal|last1=Quinn|first1=P. K.|author-link1=Patricia Quinn (scientist)|last2=Bates|first2=T. S.|year=2011|title=The case against climate regulation via oceanic phytoplankton sulphur emissions|journal=Nature|volume=480|issue=7375|pages=51–6|bibcode=2011Natur.480...51Q|doi=10.1038/nature10580|pmid=22129724|s2cid=4417436|url=https://zenodo.org/record/1233319}}</ref> Different types of phytoplankton support different [[trophic level]]s within varying ecosystems. In [[oligotroph]]ic oceanic regions such as the [[Sargasso Sea]] or the [[South Pacific Gyre]], phytoplankton is dominated by the small sized cells, called [[Photosynthetic picoplankton|picoplankton]] and nanoplankton (also referred to as picoflagellates and nanoflagellates), mostly composed of [[cyanobacteria]] (''[[Prochlorococcus]]'', ''[[Synechococcus]]'') and picoeucaryotes such as ''[[Micromonas]]''. Within more productive ecosystems, dominated by [[upwelling]] or high terrestrial inputs, larger [[dinoflagellate]]s are the more dominant phytoplankton and reflect a larger portion of the [[Biomass (ecology)|biomass]].<ref>{{cite journal|last1=Calbet|first1=A.|year=2008|title=The trophic roles of microzooplankton in marine systems|journal=ICES Journal of Marine Science|volume=65|issue=3|pages=325–31|doi=10.1093/icesjms/fsn013|doi-access=free}}</ref>

== Growth strategies ==
In the early twentieth century, [[Alfred C. Redfield]] found the similarity of the phytoplankton's elemental composition to the major dissolved nutrients in the deep ocean.<ref>{{cite book |last1=Redfield |first1=Alfred C. |year=1934 |chapter=On the Proportions of Organic Derivatives in Sea Water and their Relation to the Composition of Plankton |pages=176–92 |editor1-last=Johnstone |editor1-first=James |editor2-last=Daniel |editor2-first=Richard Jellicoe |title=James Johnstone Memorial Volume |location=Liverpool |publisher=University Press of Liverpool |oclc=13993674 }}</ref> Redfield proposed that the ratio of carbon to nitrogen to phosphorus (106:16:1) in the ocean was controlled by the phytoplankton's requirements, as phytoplankton subsequently release nitrogen and phosphorus as they are remineralized. This so-called "[[Redfield ratio]]" in describing [[stoichiometry]] of phytoplankton and seawater has become a fundamental principle to understand marine ecology, biogeochemistry and phytoplankton evolution.<ref name="Arrigo K.R 2005">{{cite journal |last1=Arrigo |first1=Kevin R. |title=Marine microorganisms and global nutrient cycles |journal=Nature |volume=437 |issue=7057 |pages=349–55 |year=2005 |pmid=16163345 |doi=10.1038/nature04159 |bibcode=2005Natur.437..349A |s2cid=62781480 }}</ref> However, the Redfield ratio is not a universal value and it may diverge due to the changes in exogenous nutrient delivery<ref>{{cite journal |last1=Fanning |first1=Kent A. |title=Influence of atmospheric pollution on nutrient limitation in the ocean |journal=Nature |volume=339 |issue=6224 |year=1989 |pages=460–63 |bibcode=1989Natur.339..460F |doi=10.1038/339460a0 |s2cid=4247689 }}</ref> and microbial metabolisms in the ocean, such as [[nitrogen fixation]], [[denitrification]] and [[anammox]].

The dynamic stoichiometry shown in unicellular algae reflects their capability to store nutrients in an internal pool, shift between enzymes with various nutrient requirements and alter osmolyte composition.<ref>{{cite book |first1=Robert Warner |last1=Sterner |first2=James J. |last2=Elser |year=2002 |title=Ecological Stoichiometry: The Biology of Elements from Molecules to the Biosphere |publisher=Princeton University Press |isbn=978-0-691-07491-7 }}{{page needed|date=February 2016}}</ref><ref>{{cite journal |last1=Klausmeier |first1=Christopher A. |last2=Litchman |first2=Elena |author-link2=Elena Litchman|last3=Levin |first3=Simon A. |title=Phytoplankton growth and stoichiometry under multiple nutrient limitation |journal=Limnology and Oceanography |volume=49 |issue=4 Part 2 |year=2004 |pages=1463–70 |doi=10.4319/lo.2004.49.4_part_2.1463 |bibcode=2004LimOc..49.1463K |s2cid=16438669 |doi-access= }}</ref> Different cellular components have their own unique stoichiometry characteristics,<ref name="Arrigo K.R 2005"/> for instance, resource (light or nutrients) acquisition machinery such as proteins and chlorophyll contain a high concentration of nitrogen but low in phosphorus. Meanwhile, growth machinery such as ribosomal RNA contains high nitrogen and phosphorus concentrations.

Based on allocation of resources, phytoplankton is classified into three different growth strategies, namely survivalist, bloomer<ref>{{cite journal |last1=Klausmeier |first1=Christopher A. |last2=Litchman |first2=Elena |author-link2=Elena Litchman|last3=Daufresne |first3=Tanguy |last4=Levin |first4=Simon A. |title=Optimal nitrogen-to-phosphorus stoichiometry of phytoplankton |journal=Nature |volume=429 |issue=6988 |pages=171–4 |year=2004 |pmid=15141209 |bibcode=2004Natur.429..171K |doi=10.1038/nature02454 |s2cid=4308845 }}</ref> and generalist. Survivalist phytoplankton has a high ratio of N:P (>30) and contains an abundance of resource-acquisition machinery to sustain growth under scarce resources. Bloomer phytoplankton has a low N:P ratio (<10), contains a high proportion of growth machinery, and is adapted to exponential growth. Generalist phytoplankton has similar N:P to the Redfield ratio and contain relatively equal resource-acquisition and growth machinery.

==Factors affecting abundance==
The [[NAAMES study]] was a five-year scientific research program conducted between 2015 and 2019 by scientists from [[Oregon State University]] and [[NASA]] to investigated aspects of phytoplankton dynamics in ocean ecosystems, and how such dynamics influence [[Atmospheric aerosol particles|atmospheric aerosols]], clouds, and climate (NAAMES stands for the North Atlantic Aerosols and Marine Ecosystems Study). The study focused on the sub-arctic region of the North Atlantic Ocean, which is the site of one of Earth's largest recurring phytoplankton blooms. The long history of research in this location, as well as relative ease of accessibility, made the North Atlantic an ideal location to test prevailing scientific hypotheses<ref name=Behrenfeld2018>Behrenfeld, M.J. and Boss, E.S. (2018) "Student's tutorial on bloom hypotheses in the context of phytoplankton annual cycles". ''Global change biology'', '''24'''(1): 55–77. {{doi|10.1111/gcb.13858}}.</ref> in an effort to better understand the role of phytoplankton aerosol emissions on Earth's energy budget.<ref name=Behrenfeld2019>{{Cite journal|last1=Behrenfeld|first1=Michael J.|last2=Moore|first2=Richard H.|last3=Hostetler|first3=Chris A.|last4=Graff|first4=Jason|last5=Gaube|first5=Peter|last6=Russell|first6=Lynn M.|last7=Chen|first7=Gao|last8=Doney|first8=Scott C.|last9=Giovannoni|first9=Stephen|last10=Liu|first10=Hongyu|last11=Proctor|first11=Christopher|date=2019-03-22|title=The North Atlantic Aerosol and Marine Ecosystem Study (NAAMES): Science Motive and Mission Overview|journal=Frontiers in Marine Science|volume=6|pages=122|doi=10.3389/fmars.2019.00122|issn=2296-7745|doi-access=free}}</ref>

NAAMES was designed to target specific phases of the annual phytoplankton cycle: minimum, climax and the intermediary decreasing and increasing biomass, in order to resolve debates on the timing of bloom formations and the patterns driving annual bloom re-creation.<ref name=Behrenfeld2019 /> The NAAMES project also investigated the quantity, size, and composition of aerosols generated by [[primary production]] in order to understand how phytoplankton bloom cycles affect cloud formations and climate.<ref name=Engel2017>{{Cite journal|last1=Engel|first1=Anja|last2=Bange|first2=Hermann W.|last3=Cunliffe|first3=Michael|last4=Burrows|first4=Susannah M.|last5=Friedrichs|first5=Gernot|last6=Galgani|first6=Luisa|last7=Herrmann|first7=Hartmut|last8=Hertkorn|first8=Norbert|last9=Johnson|first9=Martin|last10=Liss|first10=Peter S.|last11=Quinn|first11=Patricia K.|author-link11=Patricia Quinn (scientist)|date=2017-05-30|title=The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer|journal=Frontiers in Marine Science|volume=4|doi=10.3389/fmars.2017.00165|issn=2296-7745|doi-access=free|hdl=10026.1/16046|hdl-access=free}}</ref>

[[File:Competing scientific hypothesis of plankton variability.png|alt=|thumb|upright=1.7|left| {{center|'''Competing hypothesis of plankton variability<ref name=Behrenfeld2018 />'''<br /><small>Figure adapted from Behrenfeld & Boss 2014.<ref>{{Cite journal|last1=Behrenfeld|first1=Michael J.|last2=Boss|first2=Emmanuel S.|date=2014-01-03|title=Resurrecting the Ecological Underpinnings of Ocean Plankton Blooms|journal=Annual Review of Marine Science|volume=6|issue=1|pages=167–194|doi=10.1146/annurev-marine-052913-021325|pmid=24079309|issn=1941-1405|bibcode=2014ARMS....6..167B|s2cid=12903662|doi-access=free}}</ref><br />Courtesy of NAAMES, Langley Research Center, NASA<ref>[https://web.archive.org/web/20160724231652/http://naames.larc.nasa.gov/science-objectives.html NAAMES: Science - Objectives] Langley Research Center, NASA, Updated: 6 June 2020. Retrieved: 15 June 2020.</ref></small>}}]]

[[File:Plankton satellite image.jpg|thumb|upright=1.7|right| World concentrations of surface ocean chlorophyll as viewed by satellite during the northern spring, averaged from 1998 to 2004. Chlorophyll is a marker for the distribution and abundance of phytoplankton.]]

[[File:Global phytoplankton species richness and turnover.jpg|thumb|upright=1.7|right| {{center|'''Global patterns of monthly phytoplankton species richness and species turnover'''}} (A) Annual mean of monthly species richness and (B) month-to-month species turnover projected by SDMs. Latitudinal gradients of (C) richness and (D) turnover. Colored lines (regressions with local polynomial fitting) indicate the means per degree latitude from three different SDM algorithms used (red shading denotes ±1 SD from 1000 Monte Carlo runs that used varying predictors for GAM). Poleward of the thin horizontal lines shown in (C) and (D), the model results cover only <12 or <9 months, respectively.<ref name=Righetti2019>Righetti, D., Vogt, M., Gruber, N., Psomas, A. and Zimmermann, N.E. (2019) "Global pattern of phytoplankton diversity driven by temperature and environmental variability". ''Science advances'', '''5'''(5): eaau6253. {{doi|10.1126/sciadv.aau6253}}. [[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>]]

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==Factors affecting productivity==
[[File:Environmental factors that affect phytoplankton productivity.webp|thumb|upright=2.1|right| {{center|Environmental factors that affect phytoplankton productivity{{hsp}}<ref name=Beardall2009>{{cite journal |doi=10.1080/17550870903271363 |title=Living in a high CO2world: Impacts of global climate change on marine phytoplankton |year=2009 |last1=Beardall |first1=John |last2=Stojkovic |first2=Slobodanka |last3=Larsen |first3=Stuart |journal=Plant Ecology & Diversity |volume=2 |issue=2 |pages=191–205 |s2cid=83586220 |doi-access=free|bibcode=2009PlEcD...2..191B }}</ref><ref name=Basu2018>{{cite journal |doi=10.3390/su10030869 |title=Phytoplankton as Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate |journal=Sustainability |year=2018 |volume=10 |issue=3 |page=869 |doi-access=free |last1=Basu |first1=Samarpita |last2=MacKey |first2=Katherine}} [[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>}}]]

Phytoplankton are the key mediators of the [[biological pump]]. Understanding the response of phytoplankton to changing environmental conditions is a prerequisite to predict future atmospheric concentrations of CO<sub>2</sub>. Temperature, irradiance and nutrient concentrations, along with CO<sub>2</sub> are the chief environmental factors that influence the physiology and [[stoichiometry]] of phytoplankton.<ref>{{cite journal |doi = 10.5194/bg-15-2761-2018|title = Marine phytoplankton stoichiometry mediates nonlinear interactions between nutrient supply, temperature, and atmospheric CO<sub>2</sub>|year = 2018|last1 = Moreno|first1 = Allison R.|last2 = Hagstrom|first2 = George I.|last3 = Primeau|first3 = Francois W.|last4 = Levin|first4 = Simon A.|last5 = Martiny|first5 = Adam C.|journal = Biogeosciences|volume = 15|issue = 9|pages = 2761–2779|bibcode = 2018BGeo...15.2761M|doi-access = free}}</ref> The stoichiometry or elemental composition of phytoplankton is of utmost importance to secondary producers such as copepods, fish and shrimp, because it determines the nutritional quality and influences energy flow through the [[marine food chain]]s.<ref name=Li2012>{{cite journal |doi = 10.1371/journal.pone.0051590|title = Interactive Effects of Ocean Acidification and Nitrogen-Limitation on the Diatom Phaeodactylum tricornutum|year = 2012|last1 = Li|first1 = Wei|last2 = Gao|first2 = Kunshan|last3 = Beardall|first3 = John|journal = PLOS ONE|volume = 7|issue = 12|pages = e51590|pmid = 23236517|pmc = 3517544|bibcode = 2012PLoSO...751590L|doi-access = free}}</ref> [[Climate change]] may greatly restructure phytoplankton communities leading to [[Trophic cascade|cascading]] consequences for [[marine food web]]s, thereby altering the amount of carbon transported to the ocean interior.<ref>{{cite journal |doi = 10.1073/pnas.1414752112|title = Phytoplankton adapt to changing ocean environments|year = 2015|last1 = Irwin|first1 = Andrew J.|last2 = Finkel|first2 = Zoe V.|last3 = Müller-Karger|first3 = Frank E.|last4 = Troccoli Ghinaglia|first4 = Luis|journal = Proceedings of the National Academy of Sciences|volume = 112|issue = 18|pages = 5762–5766|pmid = 25902497|pmc = 4426419|bibcode = 2015PNAS..112.5762I|doi-access = free}}</ref><ref name=Beardall2009 />

The figure gives an overview of the various environmental factors that together affect [[Marine primary production|phytoplankton productivity]]. All of these factors are expected to undergo significant changes in the future ocean due to global change.<ref name="Häder2014">{{cite journal |doi = 10.1039/C3PP50418B|title = Productivity of aquatic primary producers under global climate change|year = 2014|last1 = Häder|first1 = Donat-P.|last2 = Villafañe|first2 = Virginia E.|last3 = Helbling|first3 = E. Walter|journal = Photochem. Photobiol. Sci.|volume = 13|issue = 10|pages = 1370–1392|pmid = 25191675|doi-access = free| bibcode=2014PhPhS..13.1370H |hdl = 11336/24725|hdl-access = free}}</ref> Global warming simulations predict oceanic temperature increase; dramatic changes in [[oceanic stratification]], circulation and changes in cloud cover and sea ice, resulting in an increased light supply to the ocean surface. Also, reduced nutrient supply is predicted to co-occur with ocean acidification and warming, due to increased stratification of the water column and reduced mixing of nutrients from the deep water to the surface.<ref>{{cite journal |doi = 10.1029/2003GB002134|title = Response of ocean ecosystems to climate warming|year = 2004|last1 = Sarmiento|first1 = J. L.|last2 = Slater|first2 = R.|last3 = Barber|first3 = R.|last4 = Bopp|first4 = L.|last5 = Doney|first5 = S. C.|last6 = Hirst|first6 = A. C.|last7 = Kleypas|first7 = J.|last8 = Matear|first8 = R.|last9 = Mikolajewicz|first9 = U.|last10 = Monfray|first10 = P.|last11 = Soldatov|first11 = V.|last12 = Spall|first12 = S. A.|last13 = Stouffer|first13 = R.|journal = Global Biogeochemical Cycles|volume = 18|issue = 3|pages = n/a|bibcode = 2004GBioC..18.3003S|doi-access = free|hdl = 1912/3392|hdl-access = free}}</ref><ref name=Beardall2009 />

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==Role of phytoplankton==
[[File:Role of phytoplankton on various compartments of the marine environment.png|thumb|upright=2.1| {{center|Role of phytoplankton on various compartments of the marine environment{{hsp}}<ref name=Heinrichs2020 />}}]]

The compartments influenced by phytoplankton include the atmospheric gas composition, inorganic nutrients, and trace element fluxes as well as the transfer and cycling of organic matter via biological processes (see figure). The photosynthetically fixed carbon is rapidly recycled and reused in the surface ocean, while a certain fraction of this biomass is exported as sinking particles to the deep ocean, where it is subject to ongoing transformation processes, e.g., remineralization.<ref name=Heinrichs2020>{{cite book |doi = 10.1007/978-3-030-20389-4_15|chapter = Complex Interactions Between Aquatic Organisms and Their Chemical Environment Elucidated from Different Perspectives|title = YOUMARES 9 - the Oceans: Our Research, Our Future|year = 2020|last1 = Heinrichs|first1 = Mara E.|last2 = Mori|first2 = Corinna|last3 = Dlugosch|first3 = Leon|pages = 279–297|isbn = 978-3-030-20388-7|s2cid = 210308256}} [[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>

Phytoplankton contribute to not only a basic pelagic marine food web but also to the microbial loop. Phytoplankton are the base of the marine food web and because they do not rely on other organisms for food, they make up the first trophic level. Organisms such as zooplankton feed on these phytoplankton which are in turn fed on by other organisms and so forth until the fourth trophic level is reached with apex predators. Approximately 90% of total carbon is lost between trophic levels due to respiration, detritus, and dissolved organic matter. This makes the remineralization process and nutrient cycling performed by phytoplankton and bacteria important in maintaining efficiency.<ref>{{Cite book |author=Lalli, Carol M. |url=http://worldcat.org/oclc/837077589 |title=Biological oceanography an introduction |date=16 May 1997 |publisher=Elsevier Science |isbn=978-0-7506-3384-0 |oclc=837077589}}</ref>

Phytoplankton blooms in which a species increases rapidly under conditions favorable to growth can produce [[harmful algal bloom]]s (HABs).

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== Aquaculture ==
{{see also|Algaculture|Culture of microalgae in hatcheries}}

Phytoplankton are a key food item in both [[aquaculture]] and [[mariculture]]. Both utilize phytoplankton as food for the animals being farmed. In mariculture, the phytoplankton is naturally occurring and is introduced into enclosures with the normal circulation of seawater. In aquaculture, phytoplankton must be obtained and introduced directly. The plankton can either be collected from a body of water or cultured, though the former method is seldom used. Phytoplankton is used as a foodstock for the production of [[rotifer]]s,<ref name=mcvey>McVey, James P., Nai-Hsien Chao, and Cheng-Sheng Lee. CRC Handbook of Mariculture Vol. 1 : Crustacean Aquaculture. New York: CRC Press LLC, 1993.{{page needed|date=February 2016}}</ref> which are in turn used to feed other organisms. Phytoplankton is also used to feed many varieties of aquacultured [[molluscs]], including [[pearl]] [[oyster]]s and [[giant clam]]s. A 2018 study estimated the nutritional value of natural phytoplankton in terms of carbohydrate, protein and lipid across the world ocean using ocean-colour data from satellites,<ref name=sroy>{{cite journal|last1=Roy|first1=Shovonlal|title=Distributions of phytoplankton carbohydrate, protein and lipid in the world oceans from satellite ocean colour|journal=The ISME Journal|volume=12|issue=6|pages=1457–1472|date=12 February 2018|doi=10.1038/s41396-018-0054-8|pmid=29434313|pmc=5955997|bibcode=2018ISMEJ..12.1457R |language=En|issn=1751-7370}}</ref> and found the calorific value of phytoplankton to vary considerably across different oceanic regions and between different time of the year.<ref name=sroy/><ref>{{cite news|title=Nutrition study reveals instability in world's most important fishing regions|url=https://phys.org/news/2018-02-nutrition-reveals-instability-world-important.html}}</ref>

The production of phytoplankton under artificial conditions is itself a form of aquaculture. Phytoplankton is cultured for a variety of purposes, including foodstock for other aquacultured organisms,<ref name=mcvey/> a nutritional supplement for captive [[invertebrate]]s in [[Aquarium|aquaria]]. Culture sizes range from small-scale [[laboratory]] cultures of less than 1L to several tens of thousands of litres for commercial aquaculture.<ref name=mcvey/> Regardless of the size of the culture, certain conditions must be provided for efficient growth of plankton. The majority of cultured plankton is marine, and [[seawater]] of a [[specific gravity]] of 1.010 to 1.026 may be used as a culture medium. This water must be [[Sterilization (microbiology)|sterilized]], usually by either high temperatures in an [[autoclave]] or by exposure to [[ultraviolet radiation]], to prevent [[biological]] [[contamination]] of the culture. Various [[fertilizer]]s are added to the culture medium to facilitate the growth of plankton. A culture must be aerated or agitated in some way to keep plankton suspended, as well as to provide dissolved [[carbon dioxide]] for [[photosynthesis]]. In addition to constant aeration, most cultures are manually mixed or stirred on a regular basis. Light must be provided for the growth of phytoplankton. The [[colour temperature]] of illumination should be approximately 6,500 K, but values from 4,000 K to upwards of 20,000 K have been used successfully. The duration of light exposure should be approximately 16 hours daily; this is the most efficient artificial day length.<ref name=mcvey/>
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==Anthropogenic changes==
[[File:PhytoplanktonSRvsTemp.png|thumb|upright=1.4| {{center|Plot demonstrating increases in phytoplankton species richness with increased temperature}}]]
{{see also|Human impact on marine life}}

Marine phytoplankton perform half of the global photosynthetic CO<sub>2</sub> fixation (net global primary production of ~50 Pg C per year) and half of the oxygen production despite amounting to only ~1% of global plant biomass.<ref name=Behrenfeld2014>{{cite journal |doi = 10.1038/nclimate2349|title = Climate-mediated dance of the plankton|year = 2014|last1 = Behrenfeld|first1 = Michael J.|journal = Nature Climate Change|volume = 4|issue = 10|pages = 880–887|bibcode = 2014NatCC...4..880B}}</ref> In comparison with terrestrial plants, marine phytoplankton are distributed over a larger surface area, are exposed to less seasonal variation and have markedly faster turnover rates than trees (days versus decades).<ref name=Behrenfeld2014 /> Therefore, phytoplankton respond rapidly on a global scale to climate variations. These characteristics are important when one is evaluating the contributions of phytoplankton to carbon fixation and forecasting how this production may change in response to perturbations. Predicting the effects of [[climate change]] on primary productivity is complicated by phytoplankton bloom cycles that are affected by both bottom-up control (for example, availability of essential nutrients and vertical mixing) and top-down control (for example, grazing and viruses).<ref>{{cite journal |doi = 10.1038/nclimate3147|title = Marine phytoplankton and the changing ocean iron cycle|year = 2016|last1 = Hutchins|first1 = D. A.|last2 = Boyd|first2 = P. W.|journal = Nature Climate Change|volume = 6|issue = 12|pages = 1072–1079|bibcode = 2016NatCC...6.1072H}}</ref><ref name=Behrenfeld2014 /><ref>{{cite journal |doi = 10.1038/373412a0 |title = Importance of iron for plankton blooms and carbon dioxide drawdown in the Southern Ocean |year = 1995 |last1 = De Baar |first1 = Hein J. W. |last2 = De Jong |first2 = Jeroen T. M. |last3 = Bakker |first3 = Dorothée C. E. |last4 = Löscher |first4 = Bettina M. |last5 = Veth |first5 = Cornelis |last6 = Bathmann |first6 = Uli |last7 = Smetacek |first7 = Victor |journal = Nature |volume = 373 |issue = 6513 |pages = 412–415 |bibcode = 1995Natur.373..412D |s2cid = 4257465 }}</ref><ref>{{cite journal|doi = 10.1126/science.1131669|title = Mesoscale Iron Enrichment Experiments 1993-2005: Synthesis and Future Directions|year = 2007|last1 = Boyd|first1 = P. W.|last2 = Jickells|first2 = T.|last3 = Law|first3 = C. S.|last4 = Blain|first4 = S.|last5 = Boyle|first5 = E. A.|last6 = Buesseler|first6 = K. O.|last7 = Coale|first7 = K. H.|last8 = Cullen|first8 = J. J.|last9 = De Baar|first9 = H. J. W.|last10 = Follows|first10 = M.|last11 = Harvey|first11 = M.|last12 = Lancelot|first12 = C.|last13 = Levasseur|first13 = M.|last14 = Owens|first14 = N. P. J.|last15 = Pollard|first15 = R.|last16 = Rivkin|first16 = R. B.|last17 = Sarmiento|first17 = J.|last18 = Schoemann|first18 = V.|last19 = Smetacek|first19 = V.|last20 = Takeda|first20 = S.|last21 = Tsuda|first21 = A.|last22 = Turner|first22 = S.|last23 = Watson|first23 = A. J.|journal = Science|volume = 315|issue = 5812|pages = 612–617|pmid = 17272712|bibcode = 2007Sci...315..612B|s2cid = 2476669|url = https://pure.rug.nl/ws/files/2797658/2007ScienceBoyd.pdf|access-date = 29 October 2020|archive-date = 2 November 2020|archive-url = https://web.archive.org/web/20201102032923/https://pure.rug.nl/ws/files/2797658/2007ScienceBoyd.pdf|url-status = dead}}</ref><ref>{{cite journal |doi = 10.1038/nclimate2838|title = Revaluating ocean warming impacts on global phytoplankton|year = 2016|last1 = Behrenfeld|first1 = Michael J.|last2 = o'Malley|first2 = Robert T.|last3 = Boss|first3 = Emmanuel S.|last4 = Westberry|first4 = Toby K.|last5 = Graff|first5 = Jason R.|last6 = Halsey|first6 = Kimberly H.|last7 = Milligan|first7 = Allen J.|last8 = Siegel|first8 = David A.|last9 = Brown|first9 = Matthew B.|journal = Nature Climate Change|volume = 6|issue = 3|pages = 323–330|bibcode = 2016NatCC...6..323B}}</ref><ref name=Behrenfeld2017>{{cite journal |doi = 10.1038/ngeo2861|title = Annual boom–bust cycles of polar phytoplankton biomass revealed by space-based lidar|year = 2017|last1 = Behrenfeld|first1 = Michael J.|last2 = Hu|first2 = Yongxiang|last3 = o'Malley|first3 = Robert T.|last4 = Boss|first4 = Emmanuel S.|last5 = Hostetler|first5 = Chris A.|last6 = Siegel|first6 = David A.|last7 = Sarmiento|first7 = Jorge L.|last8 = Schulien|first8 = Jennifer|last9 = Hair|first9 = Johnathan W.|last10 = Lu|first10 = Xiaomei|last11 = Rodier|first11 = Sharon|last12 = Scarino|first12 = Amy Jo|journal = Nature Geoscience|volume = 10|issue = 2|pages = 118–122|bibcode = 2017NatGe..10..118B}}</ref> Increases in solar radiation, temperature and freshwater inputs to surface waters strengthen [[ocean stratification]] and consequently reduce transport of nutrients from deep water to surface waters, which reduces primary productivity.<ref name=Behrenfeld2014 /><ref name=Behrenfeld2017 /><ref>{{cite journal |doi = 10.1038/nature05317|title = Climate-driven trends in contemporary ocean productivity|year = 2006|last1 = Behrenfeld|first1 = Michael J.|last2 = o'Malley|first2 = Robert T.|last3 = Siegel|first3 = David A.|last4 = McClain|first4 = Charles R.|last5 = Sarmiento|first5 = Jorge L.|last6 = Feldman|first6 = Gene C.|last7 = Milligan|first7 = Allen J.|last8 = Falkowski|first8 = Paul G.|last9 = Letelier|first9 = Ricardo M.|last10 = Boss|first10 = Emmanuel S.|journal = Nature|volume = 444|issue = 7120|pages = 752–755|pmid = 17151666|bibcode = 2006Natur.444..752B|s2cid = 4414391}}</ref> Conversely, rising CO<sub>2</sub> levels can increase phytoplankton primary production, but only when nutrients are not limiting.<ref>{{cite journal |doi = 10.1111/j.1365-2486.2006.01314.x|title = Elevated CO2 enhances nitrogen fixation and growth in the marine cyanobacterium Trichodesmium|year = 2007|last1 = Levitan|first1 = O.|last2 = Rosenberg|first2 = G.|last3 = Setlik|first3 = I.|last4 = Setlikova|first4 = E.|last5 = Grigel|first5 = J.|last6 = Klepetar|first6 = J.|last7 = Prasil|first7 = O.|last8 = Berman-Frank|first8 = I.|journal = Global Change Biology|volume = 13|issue = 2|pages = 531–538|bibcode = 2007GCBio..13..531L|s2cid = 86121269}}</ref><ref>{{cite journal |doi = 10.1111/ele.12298|title = Contrasting effects of rising CO2 on primary production and ecological stoichiometry at different nutrient levels|year = 2014|last1 = Verspagen|first1 = Jolanda M. H.|last2 = Van De Waal|first2 = Dedmer B.|last3 = Finke|first3 = Jan F.|last4 = Visser|first4 = Petra M.|last5 = Huisman|first5 = Jef|journal = Ecology Letters|volume = 17|issue = 8|pages = 951–960|pmid = 24813339| bibcode=2014EcolL..17..951V |hdl = 20.500.11755/ecac2c45-7efa-4c90-9e29-f2bafcee1c95|url = https://pure.knaw.nl/ws/files/1408909/5616_Verspagen_Postprint.pdf|hdl-access = free}}</ref><ref>{{cite journal |doi = 10.1038/nclimate2768|title = Temperature dependence of CO<sub>2</sub>-enhanced primary production in the European Arctic Ocean|year = 2015|last1 = Holding|first1 = J. M.|last2 = Duarte|first2 = C. M.|last3 = Sanz-Martín|first3 = M.|last4 = Mesa|first4 = E.|last5 = Arrieta|first5 = J. M.|last6 = Chierici|first6 = M.|last7 = Hendriks|first7 = I. E.|last8 = García-Corral|first8 = L. S.|last9 = Regaudie-De-Gioux|first9 = A.|last10 = Delgado|first10 = A.|last11 = Reigstad|first11 = M.|last12 = Wassmann|first12 = P.|last13 = Agustí|first13 = S.|journal = Nature Climate Change|volume = 5|issue = 12|pages = 1079–1082|bibcode = 2015NatCC...5.1079H|hdl = 10754/596052|hdl-access = free}}</ref><ref name=Cavicchioli2019>{{cite journal |doi = 10.1038/s41579-019-0222-5|title = Scientists' warning to humanity: Microorganisms and climate change|year = 2019|last1 = Cavicchioli|first1 = Ricardo|last2 = Ripple|first2 = William J.|last3 = Timmis|first3 = Kenneth N.|last4 = Azam|first4 = Farooq|last5 = Bakken|first5 = Lars R.|last6 = Baylis|first6 = Matthew|last7 = Behrenfeld|first7 = Michael J.|last8 = Boetius|first8 = Antje|last9 = Boyd|first9 = Philip W.|last10 = Classen|first10 = Aimée T.|last11 = Crowther|first11 = Thomas W.|last12 = Danovaro|first12 = Roberto|last13 = Foreman|first13 = Christine M.|last14 = Huisman|first14 = Jef|last15 = Hutchins|first15 = David A.|last16 = Jansson|first16 = Janet K.|last17 = Karl|first17 = David M.|last18 = Koskella|first18 = Britt|last19 = Mark Welch|first19 = David B.|last20 = Martiny|first20 = Jennifer B. H.|last21 = Moran|first21 = Mary Ann|last22 = Orphan|first22 = Victoria J.|last23 = Reay|first23 = David S.|last24 = Remais|first24 = Justin V.|last25 = Rich|first25 = Virginia I.|last26 = Singh|first26 = Brajesh K.|last27 = Stein|first27 = Lisa Y.|last28 = Stewart|first28 = Frank J.|last29 = Sullivan|first29 = Matthew B.|last30 = Van Oppen|first30 = Madeleine J. H.|journal = Nature Reviews Microbiology|volume = 17|issue = 9|pages = 569–586|pmid = 31213707|pmc = 7136171|display-authors = 29}} [[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>

Some studies indicate that overall global oceanic phytoplankton density has decreased in the past century,<ref>{{cite journal |doi = 10.1038/nature09268|title = Global phytoplankton decline over the past century|year = 2010|last1 = Boyce|first1 = Daniel G.|last2 = Lewis|first2 = Marlon R.|last3 = Worm|first3 = Boris|journal = Nature|volume = 466|issue = 7306|pages = 591–596|pmid = 20671703|bibcode = 2010Natur.466..591B|s2cid = 2413382}}</ref> but these conclusions have been questioned because of the limited availability of long-term phytoplankton data, methodological differences in data generation and the large annual and decadal variability in phytoplankton production.<ref>{{cite journal |doi = 10.1038/nature09951|title = Does blending of chlorophyll data bias temporal trend?|year = 2011|last1 = MacKas|first1 = David L.|journal = Nature|volume = 472|issue = 7342|pages = E4–E5|pmid = 21490623|bibcode = 2011Natur.472E...4M|s2cid = 4308744}}</ref><ref>{{cite journal |doi = 10.1038/nature09952|title = A measured look at ocean chlorophyll trends|year = 2011|last1 = Rykaczewski|first1 = Ryan R.|last2 = Dunne|first2 = John P.|journal = Nature|volume = 472|issue = 7342|pages = E5–E6|pmid = 21490624|bibcode = 2011Natur.472E...5R|s2cid = 205224535|url = https://zenodo.org/record/1233315}}</ref><ref>{{cite journal |doi = 10.1038/nature09950|title = Is there a decline in marine phytoplankton?|year = 2011|last1 = McQuatters-Gollop|first1 = Abigail|last2 = Reid|first2 = Philip C.|last3 = Edwards|first3 = Martin|last4 = Burkill|first4 = Peter H.|last5 = Castellani|first5 = Claudia|last6 = Batten|first6 = Sonia|last7 = Gieskes|first7 = Winfried|last8 = Beare|first8 = Doug|last9 = Bidigare|first9 = Robert R.|last10 = Head|first10 = Erica|last11 = Johnson|first11 = Rod|last12 = Kahru|first12 = Mati|last13 = Koslow|first13 = J. Anthony|last14 = Pena|first14 = Angelica|journal = Nature|volume = 472|issue = 7342|pages = E6–E7|pmid = 21490625|bibcode = 2011Natur.472E...6M|s2cid = 205224519}}</ref><ref>{{cite journal |doi = 10.1038/nature09953|title = Boyce et al. Reply|year = 2011|last1 = Boyce|first1 = Daniel G.|last2 = Lewis|first2 = Marlon R.|last3 = Worm|first3 = Boris|journal = Nature|volume = 472|issue = 7342|pages = E8–E9|bibcode = 2011Natur.472E...8B|s2cid = 4317554|doi-access = free}}</ref> Moreover, other studies suggest a global increase in oceanic phytoplankton production<ref>{{cite journal |doi = 10.1029/2004JC002620|title = Bridging ocean color observations of the 1980s and 2000s in search of long-term trends|year = 2005|last1 = Antoine|first1 = David|journal = Journal of Geophysical Research|volume = 110|issue = C6|pages = C06009|bibcode = 2005JGRC..110.6009A|doi-access = free}}</ref> and changes in specific regions or specific phytoplankton groups.<ref>{{cite journal |doi = 10.1371/journal.pone.0063766|title = Trends in Ocean Colour and Chlorophyll Concentration from 1889 to 2000, Worldwide|year = 2013|last1 = Wernand|first1 = Marcel R.|last2 = Van Der Woerd|first2 = Hendrik J.|last3 = Gieskes|first3 = Winfried W. C.|journal = PLOS ONE|volume = 8|issue = 6|pages = e63766|pmid = 23776435|pmc = 3680421|bibcode = 2013PLoSO...863766W|doi-access = free}}</ref><ref>{{cite journal |doi = 10.1002/2015GB005139|title = Recent decadal trends in global phytoplankton composition|year = 2015|last1 = Rousseaux|first1 = Cecile S.|last2 = Gregg|first2 = Watson W.|journal = Global Biogeochemical Cycles|volume = 29|issue = 10|pages = 1674–1688|bibcode = 2015GBioC..29.1674R|doi-access = free}}</ref> The global Sea Ice Index is declining,<ref>[https://nsidc.org/data/seaice_index Sea Ice Index] ''National Snow and Ice Data Center''. Accessed 30 October 2020.</ref> leading to higher light penetration and potentially more primary production;<ref>{{cite journal |doi = 10.1038/nrmicro2115|title = Microbial growth in the polar oceans – role of temperature and potential impact of climate change|year = 2009|last1 = Kirchman|first1 = David L.|last2 = Morán|first2 = Xosé Anxelu G.|last3 = Ducklow|first3 = Hugh|journal = Nature Reviews Microbiology|volume = 7|issue = 6|pages = 451–459|pmid = 19421189|s2cid = 31230080}}</ref> however, there are conflicting predictions for the effects of variable mixing patterns and changes in nutrient supply and for productivity trends in polar zones.<ref name=Behrenfeld2017 /><ref name=Cavicchioli2019 />

The effect of human-caused [[climate change]] on phytoplankton biodiversity is not well understood. Should greenhouse gas emissions continue rising to high levels by 2100, some phytoplankton models predict an increase in [[species richness]], or the number of different species within a given area. This increase in plankton diversity is traced to warming ocean temperatures. In addition to species richness changes, the locations where phytoplankton are distributed are expected to shift towards the Earth's poles. Such movement may disrupt ecosystems, because phytoplankton are consumed by zooplankton, which in turn sustain fisheries. This shift in phytoplankton location may also diminish the ability of phytoplankton to store carbon that was emitted by human activities. Human (anthropogenic) changes to phytoplankton impact both natural and economic processes.<ref>{{Cite journal|last1=Benedetti|first1=Fabio|last2=Vogt|first2=Meike|last3=Elizondo|first3=Urs Hofmann|last4=Righetti|first4=Damiano|last5=Zimmermann|first5=Niklaus E.|last6=Gruber|first6=Nicolas|date=2021-09-01|title=Major restructuring of marine plankton assemblages under global warming|journal=Nature Communications|language=en|volume=12|issue=1|pages=5226|doi=10.1038/s41467-021-25385-x|issn=2041-1723|pmc=8410869|pmid=34471105|bibcode=2021NatCo..12.5226B}}</ref>

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== See also ==
{{commons category|Phytoplankton}}
{{commons category|Algal blooms}}
{{div col}}
* {{annotated link|Algaculture}}
* {{annotated link|AlgaeBase}}
* {{annotated link|Algal bloom}}
* {{annotated link|Bacterioplankton}}
* {{annotated link|Biological pump}}
* {{annotated link|CLAW hypothesis}}
* [[Critical depth]]
* [[Deep chlorophyll maximum]]
* {{annotated link|Freshwater phytoplankton}}
* {{annotated link|Iron fertilization}}
* {{annotated link|Microphyte}} (microalgae)
* [[North Atlantic Aerosols and Marine Ecosystems Study|NAAMES]]
* {{annotated link|Ocean acidification}}
* {{annotated link|Paradox of the plankton}}
* {{annotated link|Parasites of phytoplankton}}
* {{annotated link|Photosynthetic picoplankton}}
* {{annotated link|Whiting event}}
* {{annotated link|Thin layers (oceanography)}}
{{div col end}}

{{clear}}

== References ==
{{reflist}}

== Further reading ==
*{{cite book |last1=Greeson |first1=Phillip E. |year=1982 |title=An annotated key to the identification of commonly occurring and dominant genera of Algae observed in the Phytoplankton of the United States |location=Washington, D.C. |publisher=United States Government Printing Office |url=https://pubs.er.usgs.gov/publication/wsp2079 |isbn=978-0-607-68844-3 }}
*{{cite book |last1=Kirby |first1=Richard R. |year=2010 |title=Ocean Drifters: A Secret World Beneath the Waves |publisher=Studio Cactus  |isbn=978-1-904239-10-9 }}
*{{cite journal |last1=Martin |first1=Ronald |last2=Quigg |first2=Antonietta |title=Tiny Plants That Once Ruled the Seas |journal=Scientific American |volume=308 |issue=6 |year=2013 |pages=40–5 |pmid=23729069 |doi=10.1038/scientificamerican0613-40 |bibcode=2013SciAm.308f..40M }}

== External links ==
* [http://www.secchidisk.org Secchi Disk and Secchi app], a citizen science project to study the phytoplankton
* [http://vimeo.com/84872751/ Ocean Drifters], a short film narrated by David Attenborough about the varied roles of plankton
* [http://www.planktonchronicles.org/en Plankton Chronicles], a short documentary films & photos
* [https://web.archive.org/web/20150214081038/http://saga.pmel.noaa.gov/review/dms_climate.html DMS and Climate], NOAA
* [http://planktonnet.awi.de/ Plankton*Net], images of planktonic species

{{plankton|state=expanded}}
{{aquatic ecosystem topics|expanded=none}}

{{Authority control}}

[[Category:Aquatic ecology]]
[[Category:Biological oceanography]]
[[Category:Planktology]]