Editing Phytoplankton (section)

== 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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