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Like other small plankton, the bacterioplankton are [[predation|preyed]] upon by [[zooplankton]] (usually [[protozoa]]ns), and their numbers are also controlled through [[infection]] by [[bacteriophage]]s.
Like other small plankton, the bacterioplankton are [[predation|preyed]] upon by [[zooplankton]] (usually [[protozoa]]ns), and their numbers are also controlled through [[infection]] by [[bacteriophage]]s.

== Major Groups ==

=== Photosynthetic Bacterioplankton ===
Photosynthetic bacterioplankton are responsible for a large proportion of the total primary production of aquatic food webs, supplying organic compounds to higher trophic levels. These bacteria undergo [[Photosynthesis|oxygenic]] and [[anoxygenic photosynthesis]]. Differences between these processes can be seen in the byproducts produced, the primary electron donor, and the light harvesting pigments used for energy capture.

[[Cyanobacteria]], originally named blue-green algae, are a major group of photosynthetic bacterioplankton often growing cells or filaments in colonies.<ref>{{Cite book|url=http://link.springer.com/10.1007/978-1-4757-1332-9|title=Photosynthetic Prokaryotes {{!}} SpringerLink|language=en-gb|doi=10.1007/978-1-4757-1332-9}}</ref> These organisms are the dominant group of bacterioplankton using oxygenic photosynthesis in aquatic ecosystems. Cyanobacteria, along with photosynthetic eukaryotes, are responsible for approximately half of the total global primary production<ref>{{Cite journal|last=Field|first=Christopher B.|last2=Behrenfeld|first2=Michael J.|last3=Randerson|first3=James T.|last4=Falkowski|first4=Paul|date=1998-07-10|title=Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components|url=http://science.sciencemag.org/content/281/5374/237|journal=Science|language=en|volume=281|issue=5374|pages=237–240|doi=10.1126/science.281.5374.237|issn=0036-8075|pmid=9657713}}</ref> making them key players in the food web. They use photosynthesis to generate energy in the form of organic compounds and produce oxygen as a byproduct<ref>{{Cite book|url=https://link.springer.com/chapter/10.1007/978-94-007-0388-9_1|title=Bioenergetic Processes of Cyanobacteria|last=Peschek|first=Günter A.|last2=Bernroitner|first2=Margit|last3=Sari|first3=Samira|last4=Pairer|first4=Martin|last5=Obinger|first5=Christian|date=2011|publisher=Springer, Dordrecht|isbn=9789400703520|pages=3–70|language=en|doi=10.1007/978-94-007-0388-9_1}}</ref>. Major light harvesting pigments include [[Chlorophyll|chlorophylls]], [[Phycoerythrobilin|phycoerytherin]], [[phycocyanin]] and [[Carotenoid|carotenoids]]<ref>{{Cite journal|last=Colyer|first=Christa L.|last2=Kinkade|first2=Christopher S.|last3=Viskari|first3=Pertti J.|last4=Landers|first4=James P.|date=2005-06-01|title=Analysis of cyanobacterial pigments and proteins by electrophoretic and chromatographic methods|url=https://link.springer.com/article/10.1007/s00216-004-3020-4|journal=Analytical and Bioanalytical Chemistry|language=en|volume=382|issue=3|pages=559–569|doi=10.1007/s00216-004-3020-4|issn=1618-2642}}</ref>. The majority of cyanobacteria found in marine environments are represented by the genera [[Synechococcus|''Synechococcus'']] and ''[[Prochlorococcus]]. Synechococcus'' is cosmopolitan, having been reported across temperature and tropical waters.<ref>{{Cite journal|last=Johnson|first=Paul W.|last2=Sieburth|first2=John McN.|date=1979-09-01|title=Chroococcoid cyanobacteria in the sea: A ubiquitous and diverse phototrophic biomass1|url=http://onlinelibrary.wiley.com/doi/10.4319/lo.1979.24.5.0928/abstract|journal=Limnology and Oceanography|language=en|volume=24|issue=5|pages=928–935|doi=10.4319/lo.1979.24.5.0928|issn=1939-5590}}</ref> ''Prochlorococcus'' is a very small in size and has one of the smallest photosynthetic bacterial genomes.<ref>{{Cite journal|last=Dufresne|first=Alexis|last2=Salanoubat|first2=Marcel|last3=Partensky|first3=Frédéric|last4=Artiguenave|first4=François|last5=Axmann|first5=Ilka M.|last6=Barbe|first6=Valérie|last7=Duprat|first7=Simone|last8=Galperin|first8=Michael Y.|last9=Koonin|first9=Eugene V.|date=2003-08-19|title=Genome sequence of the cyanobacterium Prochlorococcus marinus SS120, a nearly minimal oxyphototrophic genome|url=http://www.pnas.org/cgi/doi/10.1073/pnas.1733211100|journal=Proceedings of the National Academy of Sciences|volume=100|issue=17|pages=10020–10025|doi=10.1073/pnas.1733211100}}</ref><ref>{{Cite journal|last=Chisholm|first=Sallie W.|last2=Frankel|first2=Sheila L.|last3=Goericke|first3=Ralf|last4=Olson|first4=Robert J.|last5=Palenik|first5=Brian|last6=Waterbury|first6=John B.|last7=West-Johnsrud|first7=Lisa|last8=Zettler|first8=Erik R.|date=1992-02-01|title=Prochlorococcus marinus nov. gen. nov. sp.: an oxyphototrophic marine prokaryote containing divinyl chlorophyll a and b|url=https://link.springer.com/article/10.1007/BF00245165|journal=Archives of Microbiology|language=en|volume=157|issue=3|pages=297–300|doi=10.1007/bf00245165|issn=0302-8933}}</ref> It is found mainly in the euphotic zone of tropical waters<ref>{{Cite journal|last=Chisholm|first=Sallie W.|last2=Olson|first2=Robert J.|last3=Zettler|first3=Erik R.|last4=Goericke|first4=Ralf|last5=Waterbury|first5=John B.|last6=Welschmeyer|first6=Nicholas A.|date=1988/07|title=A novel free-living prochlorophyte abundant in the oceanic euphotic zone|url=http://www.nature.com/doifinder/10.1038/334340a0|journal=Nature|language=En|volume=334|issue=6180|pages=340–343|doi=10.1038/334340a0|issn=1476-4687}}</ref>. Factors including light, nutrient inputs, and temperature can cause cyanobacteria to proliferate and form harmful blooms<ref>{{Cite journal|last=Reynolds|first=C. S.|last2=Walsby|first2=A. E.|date=1975-11-01|title=Water-Blooms|url=http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.1975.tb01060.x/abstract|journal=Biological Reviews|language=en|volume=50|issue=4|pages=437–481|doi=10.1111/j.1469-185x.1975.tb01060.x|issn=1469-185X}}</ref>. Cyanobacteria blooms can cause hypoxia and produce high levels of toxins, impacting other aquatic organisms as well as causing illnesses in humans.

Some Cyanobacteria are capable of nitrogen fixation.The genus [[Anabaena|''Anabaena'']] uses specialized cells called heterocysts to localize nitrogen fixation. Physically separatating nitrogen fixation and photosynthesis is due to the toxicity of oxygen to the nitrogenase enzyme facilitating nitrogen fixation<ref>{{Cite journal|last=Agnihotri|first=Vijai K|date=|title=Anabaena flos-aquae|url=|journal=Critical Reviews in Environmental Science and Technology|volume=44|pages=1995-2037|doi=10.1080/10643389.2013.803797|via=}}</ref>. ''[[Trichodesmium]]'' is another cyanobacteria that also is capable of fixing nitrogen while undergoing photosynthesis. Instead of using heterocysts, ''Trichodesminum'' uses an alternative photosyntheitc pathway, only during daylight, to fix nitrogen<ref>{{Cite journal|last=Bergman|first=Birgitta|last2=Sandh|first2=Gustaf|last3=Lin|first3=Senjie|last4=Larsson|first4=John|last5=Carpenter|first5=Edward J.|date=2013-05-01|title=Trichodesmium– a widespread marine cyanobacterium with unusual nitrogen fixation properties|url=https://academic.oup.com/femsre/article/37/3/286/583761|journal=FEMS Microbiology Reviews|language=en|volume=37|issue=3|pages=286–302|doi=10.1111/j.1574-6976.2012.00352.x|issn=0168-6445}}</ref>.

Other photosynthetic bacterioplankton, including purple and green bacteria, undergo anoxygenic photosynthesis in anaerobic conditions. The pigments synthesized in these organisms are sensitive to oxygen. In purple bacteria the major pigments include bacteriochlorophyll a and b and carotenoids. Green bacteria have different light harvesting pigments consisting of bacteriochlorophyll c, d and e.<ref>{{Cite book|url=http://link.springer.com/10.1007/978-1-4757-1332-9|title=Photosynthetic Prokaryotes {{!}} SpringerLink|language=en-gb|doi=10.1007/978-1-4757-1332-9}}</ref> These organisms do not produce oxygen through photosynthesis or use water as a reducing agent. Many of these organisms use sulfur, hydrogen or other compounds as an energy source to drive photosynthesis. Most of these bacterioplankton are found in anoxic waters, including stagnant and hypersaline environments<ref>{{Cite journal|last=Kopylov|first=Alexander I.|last2=Kosolapov|first2=Dmitriy B.|last3=Degermendzhy|first3=Nadezhda N.|last4=Zotina|first4=Tatiana A.|last5=Romanenko|first5=Anna V.|date=2002-04-01|title=Phytoplankton, bacterial production and protozoan bacterivory in stratified, brackish-water Lake Shira (Khakasia, Siberia)|url=https://link.springer.com/article/10.1023/A:1015611023296|journal=Aquatic Ecology|language=en|volume=36|issue=2|pages=205–218|doi=10.1023/a:1015611023296|issn=1386-2588}}</ref>.

=== Heterotrophic Bacterioplankton ===
Heterotrophic bacterioplankton rely on the available concentration of dissolved organic matter in the water column. Usually these organisms are saprophytic, absorbing up nutrients from their surroundings. These heterotrophs also play a key role in the microbial loop and the remineralization of organic compounds like carbon and nitrogen. Pelagibacterales, also known as members of an alphaproteobacteria clade, are the most abundant bacterioplankton in the oceans. Members of this group are found in waters with low nutrient availability and are preyed on by protists.<ref>{{Cite journal|last=Morris|first=Robert M.|last2=Rappé|first2=Michael S.|last3=Connon|first3=Stephanie A.|last4=Vergin|first4=Kevin L.|last5=Siebold|first5=William A.|last6=Carlson|first6=Craig A.|last7=Giovannoni|first7=Stephen J.|date=2002/12|title=SAR11 clade dominates ocean surface bacterioplankton communities|url=http://dx.doi.org/10.1038/nature01240|journal=Nature|language=En|volume=420|issue=6917|pages=806–810|doi=10.1038/nature01240|issn=1476-4687}}</ref><ref>{{Cite journal|last=Cole|first=JJ|last2=Findlay|first2=S|last3=Pace|first3=ML|title=Bacterial production in fresh and saltwater ecosystems: a cross-system overview|url=http://www.int-res.com/articles/meps/43/m043p001.pdf|journal=Marine Ecology Progress Series|volume=43|pages=1–10|doi=10.3354/meps043001}}</ref>

== Biogeochemical Cycling ==

=== Carbon ===
Atmospheric carbon is sequestered into the ocean by three main pumps which have been known for 30 years: the [[solubility pump]], the [[carbonate pump]], and the [[Biological pump|biological carbon pump]] (BCP).<ref name=":0">{{Cite journal|date=2015-05-01|title=The microbial carbon pump concept: Potential biogeochemical significance in the globally changing ocean|url=https://www.sciencedirect.com/science/article/pii/S0079661115000105|journal=Progress in Oceanography|language=en|volume=134|pages=432–450|doi=10.1016/j.pocean.2015.01.008|issn=0079-6611}}</ref> The biological carbon pump is a vertical transmission pump arbitrated mainly by the sinking of organic rich particles. Bacterial phytoplankton near the surface incorporate atmospheric CO<sub>2</sub> and other nutrients into their biomass during photosynthesis. At the time of their death these phytoplankton, along with their incorporated carbon, sink to the bottom of the ocean where the carbon remains for thousands of years.<ref>{{Cite book|url=http://linkinghub.elsevier.com/retrieve/pii/B9780080959757006045|title=The Biological Pump|last=De La Rocha|first=C.L.|last2=Passow|first2=U.|pages=93–122|doi=10.1016/b978-0-08-095975-7.00604-5}}</ref> The other biologically mediated sequestration of carbon in the ocean occurs through the microbial pump. The microbial pump is responsible for the production of old recalcitrant dissolved organic carbon (DOC) which is >100 years old.<ref name=":0" /> Plankton in the ocean are incapable of breaking down this recalcitrant DOC and thus it remains in the oceans for 1000's years without being respired. The two pumps work simultaneously, and the balance between them is believed to vary based on the availability of nutrients.<ref>{{Cite journal|last=Polimene|first=Luca|last2=Sailley|first2=Sevrine|last3=Clark|first3=Darren|last4=Mitra|first4=Aditee|last5=Allen|first5=J Icarus|date=2017-03-01|title=Biological or microbial carbon pump? The role of phytoplankton stoichiometry in ocean carbon sequestration|url=https://academic.oup.com/plankt/article/39/2/180/2731670|journal=Journal of Plankton Research|language=en|volume=39|issue=2|doi=10.1093/plankt/fbw091|issn=0142-7873}}</ref> Overall, the oceans act as a sink for atmospheric CO<sub>2</sub> but also release some carbon back into the atmosphere.<ref>{{Cite book|url=https://www.worldcat.org/oclc/54974524|title=The ocean carbon cycle and climate|date=2004|publisher=Kluwer Academic Publishers|others=Follows, Mick., Oguz, Temel., North Atlantic Treaty Organization. Scientific Affairs Division.|isbn=9781402020872|location=Dordrecht|oclc=54974524}}</ref> This occurs when bacterioplankton and other organisms in the ocean consume organic matter and respire CO<sub>2</sub>, and as a result of the solubility equilibrium between the ocean and the atmosphere.

=== Nitrogen ===
The nitrogen cycle in the oceans is mediated by microorganisms, many of which are bacteria, performing multiple conversions such as: [[nitrogen fixation]], [[denitrification]], [[Nitrogen assimilation|assimilation]], and anaerobic ammonia oxidation ([[anammox]]). There are many different nitrogen metabolism strategies employed by bacterioplankton. Starting in the atmosphere N<sub>2</sub> is fixed by [[Diazotroph|diazatrophs]], such as [[trichodesmium]], into forms like ammonia (NH<sub>4</sub>).<ref>{{Cite book|url=https://www.worldcat.org/oclc/25093612|title=Marine pelagic cyanobacteria : Trichodesmium and other diazotrophs|date=1992|publisher=Kluwer Academic Publishers|others=Carpenter, Edward J., Capone, Douglas G., Rueter, J. G. (John G.), 1951-|isbn=9780792316145|location=Dordrecht|oclc=25093612}}</ref> This ammonia can be assimilated into organic matter like amino and nucleic acids, by both photoautrophic and heterotrophic plankton, it can also be [[Nitrification|nitrified]] to NO3 for energy production by nitrifying bacteria. Finally the use of NO<sub>3</sub> or NO<sub>2</sub> as [[Electron acceptor|terminal electron acceptors]] reduces the nitrogen back into N<sub>2,</sub> which is then released back into the atmosphere thus closing the cycle.<ref name=":1">{{Cite journal|last=Zehr|first=Jonathan P.|last2=Kudela|first2=Raphael M.|title=Nitrogen Cycle of the Open Ocean: From Genes to Ecosystems|url=https://www-annualreviews-org.ezproxy.library.ubc.ca/doi/10.1146/annurev-marine-120709-142819|journal=Annual Review of Marine Science|language=en|volume=3|issue=1|pages=197–225|doi=10.1146/annurev-marine-120709-142819}}</ref> Another important process involved in the regeneration of atmospheric N<sub>2</sub> is anammox.<ref name=":1" /><ref name=":2">{{Cite book|url=https://link.springer.com/chapter/10.1007/978-3-319-12415-5_7|title=Sustaining Life on Planet Earth: Metalloenzymes Mastering Dioxygen and Other Chewy Gases|last=Reimann|first=Joachim|last2=Jetten|first2=Mike S. M.|last3=Keltjens|first3=Jan T.|date=2015|publisher=Springer, Cham|isbn=9783319124148|series=Metal Ions in Life Sciences|pages=257–313|language=en|doi=10.1007/978-3-319-12415-5_7}}</ref> Anammox, a process in which ammonia is combined with nitrite in order to produce diatomic nitrogen and water, could account for 30-50% of production of N<sub>2</sub> in the ocean.<ref name=":2" />

=== Dissolved Organic Matter ===
[[Dissolved organic carbon|Dissolved organic matter]] (DOM) is available in many forms in the ocean, and is responsible for supporting the growth of bacteria and microorganisms in the ocean. The two main sources of this dissolved organic matter are; decomposition of higher trophic level organisms like plants and fish, and secondly DOM in runoffs that pass through soil with high levels of organic material. It is important to note that the age and quality of the DOM is important for its usability by microbes.<ref>{{Cite journal|last=Søndergaard|last2=Middelboe|date=1995-03-09|title=A cross-system analysis of labile dissolved organic carbon|url=http://www.int-res.com/abstracts/meps/v118/p283-294/|journal=Marine Ecology Progress Series|language=en|volume=118|pages=283–294|doi=10.3354/meps118283|issn=0171-8630}}</ref> The majority of the DOM in the oceans is refractory or semi-labile and is not available for biodegradation.<ref>{{Cite journal|last=Gruber|first=David F.|last2=Simjouw|first2=Jean-Paul|last3=Seitzinger|first3=Sybil P.|last4=Taghon|first4=Gary L.|date=2006-06-01|title=Dynamics and Characterization of Refractory Dissolved Organic Matter Produced by a Pure Bacterial Culture in an Experimental Predator-Prey System|url=http://aem.asm.org/content/72/6/4184|journal=Applied and Environmental Microbiology|language=en|volume=72|issue=6|pages=4184–4191|doi=10.1128/aem.02882-05|issn=0099-2240|pmid=16751530}}</ref> As mentioned above the microbial pump is responsible for the production of refractory DOM which is unavailable for biodegradation and remains dissolved in the oceans for thousands of years.<ref name=":0" /> The turnover of labile DOM organic material is quite high due to scarcity, this is important for the support of multiple trophic levels in the microbial community.<ref>{{Cite journal|last=Kirchman|first=David L.|last2=Suzuki|first2=Yoshimi|last3=Garside|first3=Christopher|last4=Ducklow|first4=Hugh W.|date=1991|title=High turnover rates of dissolved organic carbon during a spring phytoplankton bloom|url=https://www.nature.com/articles/352612a0|journal=Nature|language=En|volume=352|issue=6336|pages=612–614|doi=10.1038/352612a0|issn=1476-4687|via=}}</ref> The uptake and respiration of DOM by heterotrophs closes the cycle by producing CO<sub>2.</sub>

== Ecological Significance ==
Bacterioplankton such as cyanobacteria are able to have toxic blooms in eutrophic lakes which can lead to the the death of many organisms such as fish, birds, cattle, pets and humans <ref>{{cite journal|last1=Jöhnk|first1=K. D.|last2=Huisman|first2=J.|last3=Sharples|first3=J.|last4=Sommeijer|first4=B.|last5=Visser|first5=P. M.|last6=Stroom|first6=J. M.|date=2008|title=Summer heatwaves promote blooms of harmful cyanobacteria.|journal=Global Change Biology|volume=14|issue=3|page=495-512}}</ref>. A few examples of these harmful blooms is the ''Microcystis'' bloom in the year 2000 in Swan River estuary, Australia <ref>{{cite journal|last1=Atkins|first1=R.|last2=Rose|first2=T.|last3=Brown|first3=R. S.|last4=Robb|first4=M.|date=2001|title=The Microcystis cyanobacteria bloom in the Swan River–February 2000|journal=Water Science and Technology|volume=43|page=107-114}}</ref>, and the Oostvaarderplassen in the Netherlands in 2003 <ref>{{cite journal|last1=Kardinaal|first1=W. E. A.|last2=Visser|first2=P. M.|title=Cyanotoxines Drijven tot Overlast: Inventarisatie van Microcystine Concentraties 2000–2004 in Nederlandse Oppervlakte Wateren|journal=Report for the National Institute for Inland Water Management and Wastewater Treatment, the Netherlands|page=23 pp}}</ref>. The detrimental effects of these blooms can range from heart malformation in fish<ref>{{cite journal|last1=Zi|first1=J.|last2=MacIsaac|first2=H.|last3=Yang|first3=J.|last4=Xu|first4=R.|last5=Chen|first5=S.|last6=Chang|first6=X.|date=2018|title=Cyanobacteria blooms induce embryonic heart failure in an endangered fish species|journal=Aquatic Toxicology|volume=194|page=78-85}}</ref> to constraining copepod reproduction<ref>{{cite journal|last1=Engstrom-Ost|first1=J.|last2=Brutemark|first2=A.|last3=Vehmaa|first3=A.|last4=Motwani|first4=N.|last5=Katajisto|first5=T.|date=2015|title=Consequences of a cyanobacteria bloom for copepod reproduction, mortality and sex ratio|journal=Journal of Plankton Research|volume=37|issue=2|page=388-398}}</ref>.

High temperatures caused by seasonality increases stratification and preventing vertical turbulent mixing which increases competition for light that favours buoyant cyanobacteria<ref>{{cite journal|last1=Walsby|first1=A. E.|last2=Hayes|first2=P. K.|last3=Boje|first3=R.|last4=Stal|first4=L. J.|date=1997|title=The selective advantage of buoyancy provided by gas vesicles for planktonic cyanobacteria in the Baltic Sea|journal=New Phytologist|volume=136|page=407-417}}</ref><ref>{{cite journal|last1=Huisman|first1=J.|last2=Sharples|first2=J.|last3=Stroom|first3=J.|last4=Visser|first4=P. M.|last5=Kardinaal|first5=W. E. A.|last6=Verspagen|first6=J. M. H.|last7=Sommeijer|first7=B.|date=2004|title=Changes in turbulent mixing shift competition for light between phytoplankton species|journal=Ecology|volume=85|page=2960-2970}}</ref>. Higher temperatures also reduce the viscosity of water which allows faster movement which also favors buoyant species of cyanobacteria<ref>{{cite journal|last1=Jöhnk|first1=K. D.|last2=Huisman|first2=J.|last3=Sharples|first3=J.|last4=Sommeijer|first4=B.|last5=Visser|first5=P. M.|last6=Stroom|first6=J. M.|date=2008|title=Summer heatwaves promote blooms of harmful cyanobacteria.|journal=Global Change Biology|volume=14|issue=3|page=495-512}}</ref>. These species are also very competitive with the ability to create a surface cover preventing light to reach deeper species of plankton<ref>{{cite journal|last1=Walsby|first1=A. E.|last2=Hayes|first2=P. K.|last3=Boje|first3=R.|last4=Stal|first4=L. J.|date=1997|title=The selective advantage of buoyancy provided by gas vesicles for planktonic cyanobacteria in the Baltic Sea|journal=New Phytologist|volume=136|page=407-417}}</ref><ref>{{cite journal|last1=Klausmeier|first1=C. A.|last2=Litchman|first2=E.|date=2001|title=Algal games: the vertical distribution of phytoplankton in poorly mixed water columns|journal=Limnology and Oceanography|volume=46|page=1998-2007}}</ref><ref>{{cite journal|last1=Huisman|first1=J.|last2=Sharples|first2=J.|last3=Stroom|first3=J.|last4=Visser|first4=P. M.|last5=Kardinaal|first5=W. E. A.|last6=Verspagen|first6=J. M. H.|last7=Sommeijer|first7=B.|date=2004|title=Changes in turbulent mixing shift competition for light between phytoplankton species|journal=Ecology|volume=85|page=2960-2970}}</ref>.

Climate studies are also indicating that with increasing hot waves the likelihood of detrimental cyanobacterial blooms will become more of a threat to eutrophic freshwater systems<ref>{{cite journal|last1=Beniston|first1=M.|date=2004|title=The 2003 heat wave in Europe: a shape of things to come? An analysis based on Swiss climatological data and model simulations.|journal=Geophysical Research Letters|volume=31}}</ref> <ref>{{cite journal|last1=Schär|first1=C.|last2=Vidale|first2=P. L.|last3=Frei|first3=C.|last4=Häberli|first4=C.|last5=Liniger|first5=M. A.|last6=Appenzeller|first6=C.|date=2004|title=The role of increasing temperature variability in European summer heatwaves|journal=Nature|volume=427|page=332-336}}</ref> <ref>{{cite journal|last1=Stott|first1=P. A.|last2=Stone|first2=D. A.|last3=Allen|first3=M. R.|date=2004|title=Human contribution to the European heatwave of 2003|journal=Nature|volume=432|page=610-614}}</ref>. Other implications of the increasing average air temperature due to climate change is that there might be an expansion of the cyanobacterial bloom season, extending from earlier in the spring to later in the fall <ref>{{cite journal|last1=Srifa|first1=A.|last2=Phlips|first2=E. J.|last3=Cichra|first3=M. F.|last4=Hendrickson|first4=J. C.|date=2016|title=Phytoplankton dynamics in a subtropical lake dominated by cyanobacteria: Cyanobacteria ‘Like it hot’ and sometimes dry|journal=Aquatic Ecology|volume=50|issue=2|page=163-174}}</ref>.


==See also==
==See also==
Line 13: Line 45:
*[[Plankton]]
*[[Plankton]]
*[[Zooplankton]]
*[[Zooplankton]]
* [[Ocean acidification]]
* [[Marine bacteriophage|Marine Bacteriophage]]
* [[Flagellate|Flagellates]]
* [[Iron fertilization]]


==References==
==References==

Revision as of 20:16, 12 March 2018

Bacterioplankton refers to the bacterial component of the plankton that drifts in the water column. The name comes from the Ancient Greek word πλανκτος (planktos), meaning "wanderer" or "drifter" (Thurman, 1997), and bacterium, a Latin neologism coined in the 19th century by Christian Gottfried Ehrenberg. They are found in both seawater and freshwater.

Bacterioplankton occupy a range of ecological niches in marine and aquatic ecosystems. They are both primary producers and primary consumers in these ecosystems and drive global biogeochemical cycling of elements essential for life (e.g., carbon and nitrogen fixation). Many are saprotrophic, and obtain energy by consuming organic material produced by other organisms. This material may be dissolved in the medium and taken directly from there, or bacteria may live and grow in association with particulate material such as marine snow. Many other bacterioplankton species are autotrophic, and derive energy from either photosynthesis or chemosynthesis. The latter are often categorised as picophytoplankton, and include cyanobacterial groups such as Prochlorococcus and Synechococcus. Bacterioplankton play critical roles in global nitrogen fixation, nitrification, denitrification, remineralisation and methanogenesis.

Like other small plankton, the bacterioplankton are preyed upon by zooplankton (usually protozoans), and their numbers are also controlled through infection by bacteriophages.

Major Groups

Photosynthetic Bacterioplankton

Photosynthetic bacterioplankton are responsible for a large proportion of the total primary production of aquatic food webs, supplying organic compounds to higher trophic levels. These bacteria undergo oxygenic and anoxygenic photosynthesis. Differences between these processes can be seen in the byproducts produced, the primary electron donor, and the light harvesting pigments used for energy capture.

Cyanobacteria, originally named blue-green algae, are a major group of photosynthetic bacterioplankton often growing cells or filaments in colonies.[1] These organisms are the dominant group of bacterioplankton using oxygenic photosynthesis in aquatic ecosystems. Cyanobacteria, along with photosynthetic eukaryotes, are responsible for approximately half of the total global primary production[2] making them key players in the food web. They use photosynthesis to generate energy in the form of organic compounds and produce oxygen as a byproduct[3]. Major light harvesting pigments include chlorophylls, phycoerytherin, phycocyanin and carotenoids[4]. The majority of cyanobacteria found in marine environments are represented by the genera Synechococcus and Prochlorococcus. Synechococcus is cosmopolitan, having been reported across temperature and tropical waters.[5] Prochlorococcus is a very small in size and has one of the smallest photosynthetic bacterial genomes.[6][7] It is found mainly in the euphotic zone of tropical waters[8]. Factors including light, nutrient inputs, and temperature can cause cyanobacteria to proliferate and form harmful blooms[9]. Cyanobacteria blooms can cause hypoxia and produce high levels of toxins, impacting other aquatic organisms as well as causing illnesses in humans.

Some Cyanobacteria are capable of nitrogen fixation.The genus Anabaena uses specialized cells called heterocysts to localize nitrogen fixation. Physically separatating nitrogen fixation and photosynthesis is due to the toxicity of oxygen to the nitrogenase enzyme facilitating nitrogen fixation[10]. Trichodesmium is another cyanobacteria that also is capable of fixing nitrogen while undergoing photosynthesis. Instead of using heterocysts, Trichodesminum uses an alternative photosyntheitc pathway, only during daylight, to fix nitrogen[11].

Other photosynthetic bacterioplankton, including purple and green bacteria, undergo anoxygenic photosynthesis in anaerobic conditions. The pigments synthesized in these organisms are sensitive to oxygen. In purple bacteria the major pigments include bacteriochlorophyll a and b and carotenoids. Green bacteria have different light harvesting pigments consisting of bacteriochlorophyll c, d and e.[12] These organisms do not produce oxygen through photosynthesis or use water as a reducing agent. Many of these organisms use sulfur, hydrogen or other compounds as an energy source to drive photosynthesis. Most of these bacterioplankton are found in anoxic waters, including stagnant and hypersaline environments[13].

Heterotrophic Bacterioplankton

Heterotrophic bacterioplankton rely on the available concentration of dissolved organic matter in the water column. Usually these organisms are saprophytic, absorbing up nutrients from their surroundings. These heterotrophs also play a key role in the microbial loop and the remineralization of organic compounds like carbon and nitrogen. Pelagibacterales, also known as members of an alphaproteobacteria clade, are the most abundant bacterioplankton in the oceans. Members of this group are found in waters with low nutrient availability and are preyed on by protists.[14][15]

Biogeochemical Cycling

Carbon

Atmospheric carbon is sequestered into the ocean by three main pumps which have been known for 30 years: the solubility pump, the carbonate pump, and the biological carbon pump (BCP).[16] The biological carbon pump is a vertical transmission pump arbitrated mainly by the sinking of organic rich particles. Bacterial phytoplankton near the surface incorporate atmospheric CO2 and other nutrients into their biomass during photosynthesis. At the time of their death these phytoplankton, along with their incorporated carbon, sink to the bottom of the ocean where the carbon remains for thousands of years.[17] The other biologically mediated sequestration of carbon in the ocean occurs through the microbial pump. The microbial pump is responsible for the production of old recalcitrant dissolved organic carbon (DOC) which is >100 years old.[16] Plankton in the ocean are incapable of breaking down this recalcitrant DOC and thus it remains in the oceans for 1000's years without being respired. The two pumps work simultaneously, and the balance between them is believed to vary based on the availability of nutrients.[18] Overall, the oceans act as a sink for atmospheric CO2 but also release some carbon back into the atmosphere.[19] This occurs when bacterioplankton and other organisms in the ocean consume organic matter and respire CO2, and as a result of the solubility equilibrium between the ocean and the atmosphere.

Nitrogen

The nitrogen cycle in the oceans is mediated by microorganisms, many of which are bacteria, performing multiple conversions such as: nitrogen fixation, denitrification, assimilation, and anaerobic ammonia oxidation (anammox). There are many different nitrogen metabolism strategies employed by bacterioplankton. Starting in the atmosphere N2 is fixed by diazatrophs, such as trichodesmium, into forms like ammonia (NH4).[20] This ammonia can be assimilated into organic matter like amino and nucleic acids, by both photoautrophic and heterotrophic plankton, it can also be nitrified to NO3 for energy production by nitrifying bacteria. Finally the use of NO3 or NO2 as terminal electron acceptors reduces the nitrogen back into N2, which is then released back into the atmosphere thus closing the cycle.[21] Another important process involved in the regeneration of atmospheric N2 is anammox.[21][22] Anammox, a process in which ammonia is combined with nitrite in order to produce diatomic nitrogen and water, could account for 30-50% of production of N2 in the ocean.[22]

Dissolved Organic Matter

Dissolved organic matter (DOM) is available in many forms in the ocean, and is responsible for supporting the growth of bacteria and microorganisms in the ocean. The two main sources of this dissolved organic matter are; decomposition of higher trophic level organisms like plants and fish, and secondly DOM in runoffs that pass through soil with high levels of organic material. It is important to note that the age and quality of the DOM is important for its usability by microbes.[23] The majority of the DOM in the oceans is refractory or semi-labile and is not available for biodegradation.[24] As mentioned above the microbial pump is responsible for the production of refractory DOM which is unavailable for biodegradation and remains dissolved in the oceans for thousands of years.[16] The turnover of labile DOM organic material is quite high due to scarcity, this is important for the support of multiple trophic levels in the microbial community.[25] The uptake and respiration of DOM by heterotrophs closes the cycle by producing CO2.

Ecological Significance

Bacterioplankton such as cyanobacteria are able to have toxic blooms in eutrophic lakes which can lead to the the death of many organisms such as fish, birds, cattle, pets and humans [26]. A few examples of these harmful blooms is the Microcystis bloom in the year 2000 in Swan River estuary, Australia [27], and the Oostvaarderplassen in the Netherlands in 2003 [28]. The detrimental effects of these blooms can range from heart malformation in fish[29] to constraining copepod reproduction[30].

High temperatures caused by seasonality increases stratification and preventing vertical turbulent mixing which increases competition for light that favours buoyant cyanobacteria[31][32]. Higher temperatures also reduce the viscosity of water which allows faster movement which also favors buoyant species of cyanobacteria[33]. These species are also very competitive with the ability to create a surface cover preventing light to reach deeper species of plankton[34][35][36].

Climate studies are also indicating that with increasing hot waves the likelihood of detrimental cyanobacterial blooms will become more of a threat to eutrophic freshwater systems[37] [38] [39]. Other implications of the increasing average air temperature due to climate change is that there might be an expansion of the cyanobacterial bloom season, extending from earlier in the spring to later in the fall [40].

See also

References

  • Thurman, H. V. (1997). Introductory Oceanography. New Jersey, USA: Prentice Hall College. ISBN 0-13-262072-3.

External links

  1. ^ Photosynthetic Prokaryotes | SpringerLink. doi:10.1007/978-1-4757-1332-9.
  2. ^ Field, Christopher B.; Behrenfeld, Michael J.; Randerson, James T.; Falkowski, Paul (1998-07-10). "Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components". Science. 281 (5374): 237–240. doi:10.1126/science.281.5374.237. ISSN 0036-8075. PMID 9657713.
  3. ^ Peschek, Günter A.; Bernroitner, Margit; Sari, Samira; Pairer, Martin; Obinger, Christian (2011). Bioenergetic Processes of Cyanobacteria. Springer, Dordrecht. pp. 3–70. doi:10.1007/978-94-007-0388-9_1. ISBN 9789400703520.
  4. ^ Colyer, Christa L.; Kinkade, Christopher S.; Viskari, Pertti J.; Landers, James P. (2005-06-01). "Analysis of cyanobacterial pigments and proteins by electrophoretic and chromatographic methods". Analytical and Bioanalytical Chemistry. 382 (3): 559–569. doi:10.1007/s00216-004-3020-4. ISSN 1618-2642.
  5. ^ Johnson, Paul W.; Sieburth, John McN. (1979-09-01). "Chroococcoid cyanobacteria in the sea: A ubiquitous and diverse phototrophic biomass1". Limnology and Oceanography. 24 (5): 928–935. doi:10.4319/lo.1979.24.5.0928. ISSN 1939-5590.
  6. ^ Dufresne, Alexis; Salanoubat, Marcel; Partensky, Frédéric; Artiguenave, François; Axmann, Ilka M.; Barbe, Valérie; Duprat, Simone; Galperin, Michael Y.; Koonin, Eugene V. (2003-08-19). "Genome sequence of the cyanobacterium Prochlorococcus marinus SS120, a nearly minimal oxyphototrophic genome". Proceedings of the National Academy of Sciences. 100 (17): 10020–10025. doi:10.1073/pnas.1733211100.
  7. ^ Chisholm, Sallie W.; Frankel, Sheila L.; Goericke, Ralf; Olson, Robert J.; Palenik, Brian; Waterbury, John B.; West-Johnsrud, Lisa; Zettler, Erik R. (1992-02-01). "Prochlorococcus marinus nov. gen. nov. sp.: an oxyphototrophic marine prokaryote containing divinyl chlorophyll a and b". Archives of Microbiology. 157 (3): 297–300. doi:10.1007/bf00245165. ISSN 0302-8933.
  8. ^ Chisholm, Sallie W.; Olson, Robert J.; Zettler, Erik R.; Goericke, Ralf; Waterbury, John B.; Welschmeyer, Nicholas A. (1988/07). "A novel free-living prochlorophyte abundant in the oceanic euphotic zone". Nature. 334 (6180): 340–343. doi:10.1038/334340a0. ISSN 1476-4687. {{cite journal}}: Check date values in: |date= (help)
  9. ^ Reynolds, C. S.; Walsby, A. E. (1975-11-01). "Water-Blooms". Biological Reviews. 50 (4): 437–481. doi:10.1111/j.1469-185x.1975.tb01060.x. ISSN 1469-185X.
  10. ^ Agnihotri, Vijai K. "Anabaena flos-aquae". Critical Reviews in Environmental Science and Technology. 44: 1995–2037. doi:10.1080/10643389.2013.803797.
  11. ^ Bergman, Birgitta; Sandh, Gustaf; Lin, Senjie; Larsson, John; Carpenter, Edward J. (2013-05-01). "Trichodesmium– a widespread marine cyanobacterium with unusual nitrogen fixation properties". FEMS Microbiology Reviews. 37 (3): 286–302. doi:10.1111/j.1574-6976.2012.00352.x. ISSN 0168-6445.
  12. ^ Photosynthetic Prokaryotes | SpringerLink. doi:10.1007/978-1-4757-1332-9.
  13. ^ Kopylov, Alexander I.; Kosolapov, Dmitriy B.; Degermendzhy, Nadezhda N.; Zotina, Tatiana A.; Romanenko, Anna V. (2002-04-01). "Phytoplankton, bacterial production and protozoan bacterivory in stratified, brackish-water Lake Shira (Khakasia, Siberia)". Aquatic Ecology. 36 (2): 205–218. doi:10.1023/a:1015611023296. ISSN 1386-2588.
  14. ^ Morris, Robert M.; Rappé, Michael S.; Connon, Stephanie A.; Vergin, Kevin L.; Siebold, William A.; Carlson, Craig A.; Giovannoni, Stephen J. (2002/12). "SAR11 clade dominates ocean surface bacterioplankton communities". Nature. 420 (6917): 806–810. doi:10.1038/nature01240. ISSN 1476-4687. {{cite journal}}: Check date values in: |date= (help)
  15. ^ Cole, JJ; Findlay, S; Pace, ML. "Bacterial production in fresh and saltwater ecosystems: a cross-system overview" (PDF). Marine Ecology Progress Series. 43: 1–10. doi:10.3354/meps043001.
  16. ^ a b c "The microbial carbon pump concept: Potential biogeochemical significance in the globally changing ocean". Progress in Oceanography. 134: 432–450. 2015-05-01. doi:10.1016/j.pocean.2015.01.008. ISSN 0079-6611.
  17. ^ De La Rocha, C.L.; Passow, U. The Biological Pump. pp. 93–122. doi:10.1016/b978-0-08-095975-7.00604-5.
  18. ^ Polimene, Luca; Sailley, Sevrine; Clark, Darren; Mitra, Aditee; Allen, J Icarus (2017-03-01). "Biological or microbial carbon pump? The role of phytoplankton stoichiometry in ocean carbon sequestration". Journal of Plankton Research. 39 (2). doi:10.1093/plankt/fbw091. ISSN 0142-7873.
  19. ^ The ocean carbon cycle and climate. Follows, Mick., Oguz, Temel., North Atlantic Treaty Organization. Scientific Affairs Division. Dordrecht: Kluwer Academic Publishers. 2004. ISBN 9781402020872. OCLC 54974524.{{cite book}}: CS1 maint: others (link)
  20. ^ Marine pelagic cyanobacteria : Trichodesmium and other diazotrophs. Carpenter, Edward J., Capone, Douglas G., Rueter, J. G. (John G.), 1951-. Dordrecht: Kluwer Academic Publishers. 1992. ISBN 9780792316145. OCLC 25093612.{{cite book}}: CS1 maint: others (link)
  21. ^ a b Zehr, Jonathan P.; Kudela, Raphael M. "Nitrogen Cycle of the Open Ocean: From Genes to Ecosystems". Annual Review of Marine Science. 3 (1): 197–225. doi:10.1146/annurev-marine-120709-142819.
  22. ^ a b Reimann, Joachim; Jetten, Mike S. M.; Keltjens, Jan T. (2015). Sustaining Life on Planet Earth: Metalloenzymes Mastering Dioxygen and Other Chewy Gases. Metal Ions in Life Sciences. Springer, Cham. pp. 257–313. doi:10.1007/978-3-319-12415-5_7. ISBN 9783319124148.
  23. ^ Søndergaard; Middelboe (1995-03-09). "A cross-system analysis of labile dissolved organic carbon". Marine Ecology Progress Series. 118: 283–294. doi:10.3354/meps118283. ISSN 0171-8630.
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  27. ^ Atkins, R.; Rose, T.; Brown, R. S.; Robb, M. (2001). "The Microcystis cyanobacteria bloom in the Swan River–February 2000". Water Science and Technology. 43: 107-114.
  28. ^ Kardinaal, W. E. A.; Visser, P. M. "Cyanotoxines Drijven tot Overlast: Inventarisatie van Microcystine Concentraties 2000–2004 in Nederlandse Oppervlakte Wateren". Report for the National Institute for Inland Water Management and Wastewater Treatment, the Netherlands: 23 pp.
  29. ^ Zi, J.; MacIsaac, H.; Yang, J.; Xu, R.; Chen, S.; Chang, X. (2018). "Cyanobacteria blooms induce embryonic heart failure in an endangered fish species". Aquatic Toxicology. 194: 78-85.
  30. ^ Engstrom-Ost, J.; Brutemark, A.; Vehmaa, A.; Motwani, N.; Katajisto, T. (2015). "Consequences of a cyanobacteria bloom for copepod reproduction, mortality and sex ratio". Journal of Plankton Research. 37 (2): 388-398.
  31. ^ Walsby, A. E.; Hayes, P. K.; Boje, R.; Stal, L. J. (1997). "The selective advantage of buoyancy provided by gas vesicles for planktonic cyanobacteria in the Baltic Sea". New Phytologist. 136: 407-417.
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