Editing Algal bloom (section)

==Characterization==
The term ''algal bloom'' is defined inconsistently depending on the scientific field and can range from a "minibloom"{{definition|date=October 2021}} of harmless algae to a large, harmful bloom event.<ref name=":02">{{Cite journal|last=Smayda|first=Theodore J.|date=1997|title=What is a bloom? A commentary|journal=Limnology and Oceanography|volume=42|issue=5part2|pages=1132–1136|doi=10.4319/lo.1997.42.5_part_2.1132|issn=1939-5590|bibcode=1997LimOc..42.1132S|doi-access=free}}</ref> Since ''algae'' is a broad term including organisms of widely varying sizes, growth rates, and nutrient requirements, there is no officially recognized threshold level as to what is defined as a bloom. Because there is no scientific consensus, blooms can be characterized and quantified in several ways: measurements of new algal biomass, the concentration of photosynthetic pigment, quantification of the bloom's negative effect, or relative concentration of the algae compared to the rest of the microbial community.<ref name=":02" /> For example, definitions of blooms have included when the concentration of chlorophyll exceeds 100&nbsp;ug/L,<ref>{{Cite journal|last=Tett|first=P|date=1987|title=The Ecophysiology of Exceptional Blooms|journal=Rapp. P.-v. Reun. Cons. Int. Explor. Mer|volume=187|pages=47–60}}</ref> when the concentration of chlorophyll exceeds 5&nbsp;ug/L,<ref>{{Cite journal|last1=Jonsson|first1=Per R.|last2=Pavia|first2=Henrik|last3=Toth|first3=Gunilla|date=7 July 2009|title=Formation of harmful algal blooms cannot be explained by allelopathic interactions|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=106|issue=27|pages=11177–11182|doi=10.1073/pnas.0900964106|issn=0027-8424|pmc=2708709|pmid=19549831|bibcode=2009PNAS..10611177J|doi-access=free}}</ref> when the species considered to be blooming exceeds concentrations of 1000 cells/mL,<ref>{{Cite book|last=Kim|first=H.G.|date=1993|chapter=Population cell volume and carbon content in monospecific dinoflagellate blooms |title=Toxic phytoplankton blooms in the sea|publisher=Elsevier |series=Developments in Marine Biology|volume=3|pages=769–773}}</ref> and when the algae species concentration simply deviates from its normal growth.<ref>{{Cite journal|last=Parker|first=M|date=1987|title=Exceptional Plankton Blooms Conclusion of Discussions: Convener's Report|journal=Rapp. P.-v. Reun. Cons. Int. Explor. Mer|volume=187|pages=108–114}}</ref><ref name=":1">{{Cite journal|last1=Carstensen|first1=Jacob|last2=Henriksen|first2=Peter|last3=Heiskanen|first3=Anna-Stiina|s2cid=15978578|date=January 2007|title=Summer algal blooms in shallow estuaries: Definition, mechanisms, and link to eutrophication|journal=Limnology and Oceanography|volume=52|issue=1|pages=370–384|doi=10.4319/lo.2007.52.1.0370|issn=0024-3590|bibcode=2007LimOc..52..370C|doi-access=|url=https://www.openaccessrepository.it/record/168864 |archive-url=https://web.archive.org/web/20240623110556/https://www.openaccessrepository.it/record/168864 |url-status=dead |archive-date=23 June 2024 |url-access=subscription}}</ref>

Blooms are the result of a nutrient needed by the particular algae being introduced to the local aquatic system. This growth-limiting nutrient is typically nitrogen or phosphorus, but can also be iron, vitamins, or amino acids.<ref name=":0" /> There are several mechanisms for the addition of these nutrients in water. In the open ocean and along coastlines, upwelling from both winds and topographical ocean floor features can draw nutrients to the [[Photic zone|photic]], or sunlit zone of the ocean.<ref>{{cite book|title=Manual on harmful marine microalgae|date=2004|publisher=UNESCO|last1=Hallegraeff|first1=Gustaaf M.|last2=Anderson|first2=Donald Mark|last3=Cembella|first3=Allan D.|last4=Enevoldsen|first4=Henrik O.|isbn=9231039482|edition=Second revised|location=Paris|oclc=493956343}}</ref> Along coastal regions and in freshwater systems, agricultural, city, and sewage runoff can cause algal blooms.<ref>{{Cite journal|last1=Gilbert|first1=Patricia M.|last2=Anderson|first2=Donald M.|last3=Gentien|first3=Patrick|last4=Graneli|first4=Edna|last5=Sellner|first5=Kevin G.|date=2005|title=The Global Complex Phenomena of Harmful Algal Blooms|url=https://www.whoi.edu/fileserver.do?id=35332&pt=2&p=28251|journal=Oceanography|volume=8|issue=2|pages=130–141}}</ref>

Algal blooms, especially large algal bloom events, can reduce the transparency of the water and can discolor the water.<ref name=":0" /> The photosynthetic pigments in the algal cells, like [[chlorophyll]] and photoprotective pigments, determine the color of the algal bloom. Depending on the organism, its pigments, and the depth in the water column, algal blooms can be green, red, brown, golden, and purple.<ref name=":0" /> Bright green blooms in freshwater systems are frequently a result of [[cyanobacteria]] (colloquially known as "blue-green algae") such as ''[[Microcystis aeruginosa|Microcystis]]''.<ref name=":0" /><ref>{{Cite journal|last1=Jacoby|first1=Jean M|last2=Collier|first2=Diane C|last3=Welch|first3=Eugene B|last4=Hardy|first4=F Joan|last5=Crayton|first5=Michele|date=2000|title=Environmental factors associated with a toxic bloom of Microcystis aeruginosa|journal=Canadian Journal of Fisheries and Aquatic Sciences|volume=57|issue=1|pages=231–240|doi=10.1139/f99-234|issn=0706-652X}}</ref> Blooms may also consist of [[macroalgal]] (non-[[phytoplanktonic]]) species. These blooms are recognizable by large blades of algae that may wash up onto the shoreline.<ref>{{Cite journal|last1=Liu|first1=Dongyan|last2=Keesing|first2=John K.|last3=Xing|first3=Qianguo|last4=Shi|first4=Ping|date=1 June 2009|title=World's largest macroalgal bloom caused by expansion of seaweed aquaculture in China|journal=Marine Pollution Bulletin|volume=58|issue=6|pages=888–895|doi=10.1016/j.marpolbul.2009.01.013|pmid=19261301|bibcode=2009MarPB..58..888L |issn=0025-326X}}</ref>

Once the nutrient is present in the water, the algae begin to grow at a much faster rate than usual. In a mini bloom, this fast growth benefits the whole ecosystem by providing food and nutrients for other organisms.<ref name=":1" />

Of particular note are the [[harmful algal bloom]]s (HABs), which are algal bloom events involving toxic or otherwise harmful phytoplankton. Many species can cause harmful algal blooms. For example, ''[[Gymnodinium nagasakiense]]'' can cause harmful [[red tide]]s, [[dinoflagellate]]s ''[[Gonyaulax polygramma]]'' can cause oxygen depletion and result in large fish kills, [[cyanobacteria]] ''[[Microcystis aeruginosa]]'' can make poisonous toxins, and [[diatom]] ''[[Chaetoceros convolutus]]'' can damage fish gills.<ref>{{Cite journal|last=Hallegraef|first=G.M.|date=1993|title=A review of harmful algal blooms and their apparent global increase|url=https://www.researchgate.net/publication/243776284|journal=Phycologia|volume=32|issue=2|pages=79–99|doi=10.2216/i0031-8884-32-2-79.1|bibcode=1993Phyco..32...79H }}</ref>

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File:Ocean phytoplankton bloom feed by the Amazon River.jpg|alt=Rivers, such as the Amazon, deposit nutrients from land into South America's tropical ocean waters, leading to thick blooms along the coastline |Rivers, such as the Amazon, deposit nutrients from land into South America's tropical ocean waters, leading to thick blooms along the coastline.{{hsp}}<ref name=NASA2012 />
File:Algal blooms at the mouth of the Amazon River.jpg|Blooms flourish in a dark plume of nutrient-rich water pouring from the mouth of the Amazon River, as seen by NASA's [[Aqua (satellite)|Aqua satellite]].<ref name=NASA2012 />
File:Coastal phytoplankton bloom change 2003–2020.jpg|Coastal phytoplankton bloom change 2003–2020<ref>[https://earthobservatory.nasa.gov/images/151374/coastal-phytoplankton-on-the-rise Coastal Phytoplankton on the Rise] 30 May 2023, ''[[NASA Earth Observatory]]''. {{PD-notice}}</ref><ref>{{cite journal | last1=Dai | first1=Yanhui | last2=Yang | first2=Shangbo | last3=Zhao | first3=Dan | last4=Hu | first4=Chuanmin | last5=Xu | first5=Wang | last6=Anderson | first6=Donald M. | last7=Li | first7=Yun | last8=Song | first8=Xiao-Peng | last9=Boyce | first9=Daniel G. | last10=Gibson | first10=Luke | last11=Zheng | first11=Chunmiao | last12=Feng | first12=Lian | title=Coastal phytoplankton blooms expand and intensify in the 21st century | journal=Nature | publisher=Springer Science and Business Media LLC | volume=615 | issue=7951 | date=2023-03-01 | issn=0028-0836 | doi=10.1038/s41586-023-05760-y | pages=280–284| pmid=36859547 | pmc=9995273 | bibcode=2023Natur.615..280D | s2cid=257282794 }}</ref>
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