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Group	Size range    (ESD)	Examples
	20 cm >	metazoans; e.g. jellyfish; Ctenophora (phylum)>ctenophores; salps and pyrosomes (pelagic Tunicata); Cephalopoda; Amphipoda
		metazoans; e.g. Pteropoda; Chaetognaths; Euphausiacea (krill); Medusae; Ctenophora (phylum)>ctenophores; salps, doliolids and pyrosomes (pelagic Tunicata); Cephalopoda; Janthina and Recluzia (two genera of gastropods); Amphipoda
	| metazoans; e.g. copepods; Medusae; Cladocera; Ostracoda; Chaetognaths; Pteropoda; Tunicata
	Micrometre>μm	large eukaryote	protists; most phytoplankton; Protozoa Foraminifera; tintinnids; other ciliates; Rotifera; juvenile metazoans – crustacean>Crustacea (copepod nauplii)
	| small eukaryotic protists; small diatoms; small flagellates; Pyrrophyta; Chrysophyta; Chlorophyta; Xanthophyta
Picoplankton >		eukaryotic protists; bacterium>bacteria; Chrysophyta
		Marine bacteriophage>marine viruses

However, some of these terms may be used with very different boundaries, especially on the larger end. The existence and importance of nano- and even smaller plankton was only discovered during the 1980s, but they are thought to make up the largest proportion of all plankton in number and diversity.The microplankton and smaller groups are microorganisms and operate at low Reynolds numbers, where the viscosity of water is more important than its mass or inertia.BOOK, Dusenbery, David B., Living at micro scale: the unexpected physics of being small, Harvard University Press, Cambridge, 2009, 978-0-674-03116-6, File:Plankton size.png| {{center|Plankton sizes by taxonomic groups{{hsp}}JOURNAL, 10.1371/journal.pbio.1001177, A Holistic Approach to Marine Eco-Systems Biology, 2011, Karsenti, Eric, Acinas, Silvia G., Bork, Peer, Bowler, Chris, De Vargas, Colomban, Raes, Jeroen, Sullivan, Matthew, Arendt, Detlev, Benzoni, Francesca, Claverie, Jean-Michel, Follows, Mick, Gorsky, Gaby, Hingamp, Pascal, Iudicone, Daniele, Jaillon, Olivier, Kandels-Lewis, Stefanie, Krzic, Uros, Not, Fabrice, Ogata, Hiroyuki, Pesant, Stéphane, Reynaud, Emmanuel Georges, Sardet, Christian, Sieracki, Michael E., Speich, Sabrina, Velayoudon, Didier, Weissenbach, Jean, Wincker, Patrick, PLOS Biology, 9, 10, e1001177, 22028628, 3196472, free, }}{{clear}}

Habitat groups

Marine plankton

Marine plankton includes marine bacteria and archaea, algae, protozoa and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries.

Freshwater plankton

Freshwater plankton are similar to marine plankton, but are found inland in the freshwaters of lakes and rivers.

Aeroplankton

File:Ocean mist and spray 2.jpg|Sea spray containing marine microorganisms can be swept high into the atmosphere and may travel the globe as aeroplankton before falling back to earth.Aeroplankton are tiny lifeforms that float and drift in the air, carried by the current of the wind; they are the atmospheric analogue to oceanic plankton. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of their tiny size. Scientists can collect them for study in traps and sweep nets from aircraft, kites or balloons.A. C. Hardy and P. S. Milne (1938) Studies in the Distribution of Insects by Aerial Currents. Journal of Animal Ecology, 7(2):199-229 Aeroplankton is made up of numerous microbes, including viruses, about 1000 different species of bacteria, around 40,000 varieties of fungi, and hundreds of species of protists, algae, mosses and liverworts that live some part of their life cycle as aeroplankton, often as spores, pollen, and wind-scattered seeds. Additionally, peripatetic microorganisms are swept into the air from terrestrial dust storms, and an even larger amount of airborne marine microorganisms are propelled high into the atmosphere in sea spray. Aeroplankton deposits hundreds of millions of airborne viruses and tens of millions of bacteria every day on every square meter around the planet.The sea surface microlayer, compared to the sub-surface waters, contains elevated concentration of bacteria and viruses.BOOK, Liss, P. S., The sea surface and global change, Cambridge University Press, Cambridge New York, 1997, 978-0-521-56273-7, 34933503, Blanchard, D.C., 1983. The production, distribution and bacterial enrichment of the sea-salt aerosol. In: Liss, P.S., Slinn, W.G.N. ŽEds.., Air–Sea Exchange of Gases and Particles. D. Reidel Publishing Co., Dordrecht, Netherlands, pp. 407-444. These materials can be transferred from the sea-surface to the atmosphere in the form of wind-generated aqueous aerosols due to their high vapour tension and a process known as volatilisation.Wallace Jr., G.T., Duce, R.A., 1978. Transport of particulate organic matter by bubbles in marine waters. Limnol. Oceanogr. 23 Ž6., 1155–1167. When airborne, these microbes can be transported long distances to coastal regions. If they hit land they can have an effect on animal, vegetation and human health.WHO, 1998. Draft guidelines for safe recreational water environments: coastal and fresh waters, draft for consultation. World Health Organization, Geneva, EOSrDRAFTr98 14, pp. 207–299. Marine aerosols that contain viruses can travel hundreds of kilometers from their source and remain in liquid form as long as the humidity is high enough (over 70%).Klassen, R. D., & Roberge, P. R. (1999). Aerosol transport modeling as an aid to understanding atmospheric corrosivity patterns. Materials & Design, 20, 159–168.Moorthy, K. K., Satheesh, S. K., & Krishna Murthy, B.V. (1998). Characteristics ofspectral optical depths and size distributions of aerosols over tropical oceanic regions. Journal of Atmospheric and Solar–Terrestrial Physics, 60, 981–992.Chow, J. C., Watson, J. G., Green, M. C., Lowenthal, D. H., Bates, B., Oslund, W., & Torre, G. (2000). Cross-border transport and spatial variability of suspended particles in Mexicali and California’s Imperial Valley. Atmospheric Environment, 34, 1833–1843. These aerosols are able to remain suspended in the atmosphere for about 31 days.Aller, J., Kuznetsova, M., Jahns, C., Kemp, P. (2005) The sea surface microlayer as a source of viral and bacterial enrichment in marine aerosols. Journal of aerosol science. Vol. 36, pp. 801-812. Evidence suggests that bacteria can remain viable after being transported inland through aerosols. Some reached as far as 200 meters at 30 meters above sea level. The process which transfers this material to the atmosphere causes further enrichment in both bacteria and viruses in comparison to either the SML or sub-surface waters (up to three orders of magnitude in some locations).Marks, R., Kruczalak, K., Jankowska, K., & Michalska, M. (2001). Bacteria and fungi in air over the GulfofGdansk and Baltic sea. Journal of Aerosol Science, 32, 237–250.

Geoplankton

{{see also|Geoplankton}}Many animals live in terrestrial environments by thriving in transient often microscopic bodies of water and moisture, these include rotifers and gastrotrichs which lay resilient eggs capable of surviving years in dry environments, and some of which can go dormant themselves. Nematodes are usually microscopic with this lifestyle. Water bears, despite only having lifespans of a few months, famously can enter suspended animation during dry or hostile conditions and survive for decades. This allows them to be ubiquitous in terrestrial environments despite needing water to grow and reproduce. Many microscopic crustacean groups like copepods and amphipods (of which sandhoppers are members) and seed shrimp are known to go dormant when dry and live in transient bodies of water too

Other groups

Gelatinous zooplankton

(File:Jellyfish swarm.jpg|thumb|upright=1|left| Jellyfish are gelatinous zooplankton.JOURNAL, 10.1016/j.tree.2018.09.001, A Paradigm Shift in the Trophic Importance of Jellyfish?, 2018, Hays, Graeme C., Doyle, Thomas K., Houghton, Jonathan D.R., Trends in Ecology & Evolution, 33, 11, 874–884, 30245075, 52336522,pure.qub.ac.uk/en/publications/a-paradigm-shift-in-the-trophic-importance-of-jellyfish(6158fa15-32f8-4167-9574-dbc08266b588).html, Graeme Hays, )Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed.{{aut|Lalli, C.M. & Parsons, T.R.}} (2001) Biological Oceanography. Butterworth-Heinemann. Gelatinous zooplankton are often transparent.{{aut|Johnsen, S.}} (2000) Transparent Animals. Scientific American 282: 62-71. All jellyfish are gelatinous zooplankton, but not all gelatinous zooplankton are jellyfish. The most commonly encountered organisms include ctenophores, medusae, salps, and Chaetognatha in coastal waters. However, almost all marine phyla, including Annelida, Mollusca and Arthropoda, contain gelatinous species, but many of those odd species live in the open ocean and the deep sea and are less available to the casual ocean observer.{{aut|Nouvian, C.}} (2007) The Deep. University of Chicago Press.{{clear}}

Ichthyoplankton

(File:Salmonlarvakils 2.jpg|thumb|Salmon egg hatching into a sac fry. In a few days, the sac fry will absorb the yolk sac and start feeding on smaller plankton.)Ichthyoplankton are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their food supply. Both eggs and larvae are themselves eaten by larger animals.What are Ichthyoplankton? Southwest Fisheries Science Center, NOAA. Modified 3 September 2007. Retrieved 22 July 2011.BOOK,books.google.com/books?id=Qdzg0Vfql2sC&pg=PA269, The Ecology of Marine Fishes: California and Adjacent Waters, 269–319, 9780520932470, Allen, Dr. Larry G., Horn, Dr. Michael H., 15 February 2005, University of California Press, Fish can produce high numbers of eggs which are often released into the open water column. Fish eggs typically have a diameter of about {{convert|1|mm}}. The newly hatched young of oviparous fish are called larvae. They are usually poorly formed, carry a large yolk sac (for nourishment), and are very different in appearance from juvenile and adult specimens. The larval period in oviparous fish is relatively short (usually only several weeks), and larvae rapidly grow and change appearance and structure (a process termed metamorphosis) to become juveniles. During this transition larvae must switch from their yolk sac to feeding on zooplankton prey, a process which depends on typically inadequate zooplankton density, starving many larvae. In time fish larvae become able to swim against currents, at which point they cease to be plankton and become juvenile fish.

Holoplankton

File:Tomopteriskils.jpg|thumb|left| Tomopteris, a holoplanktic bioluminescence polychaetepolychaeteHoloplankton are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their life cycle in the benthic zone. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, krill, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone.WEB, Anderson, Genny, Marine Plankton,marinebio.net/marinescience/03ecology/mlplankton.htm, Marine Science, 2012-04-04, Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists.WEB, Talks, Ted, Zooplankton,marinebio.org/oceans/zooplankton.asp,webarchive.loc.gov/all/20171207180052marinebio.org/oceans/zooplankton/, dead, 2017-12-07, Marine Life/Marine Invertebrates, 2012-04-04, {{clear}}

Meroplankton

File:Larva de phyllosoma.jpg|thumb|right| {{center|Larva stage of a spiny lobster}}]]Meroplankton are a wide variety of aquatic organisms that have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organisms.JOURNAL, Stübner, E. I., Søreide, J. E., 2016-01-27, Year-round meroplankton dynamics in high-Arctic Svalbard,academic.oup.com/plankt/article/38/3/522/2223522, Journal of Plankton Research, 38, 3, 522–536, 10.1093/plankt/fbv124, free, Meroplankton can be contrasted with holoplankton, which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle.WEB, Plankton,www.britannica.com/science/plankton, 2020-06-13, Britannica, After some time in the plankton, many meroplankton graduate to the nekton or adopt a benthic (often sessile) lifestyle on the seafloor. The larval stages of benthic invertebrates make up a significant proportion of planktonic communities.JOURNAL, Ershova, E. A., Descoteaux, R., 2019-08-13, Diversity and Distribution of Meroplanktonic Larvae in the Pacific Arctic and Connectivity With Adult Benthic Invertebrate Communities, Frontiers in Marine Science, 6, 10.3389/fmars.2019.00490, 199638114, free, 10037/16483, free, The planktonic larval stage is particularly crucial to many benthic invertebrates in order to disperse their young. Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in the pelagic zone for durations ranging from hours to months.

Pseudoplankton

Pseudoplankton are organisms that attach themselves to planktonic organisms or other floating objects, such as drifting wood, buoyant shells of organisms such as Spirula, or man-made flotsam. Examples include goose barnacles and the bryozoan Jellyella. By themselves these animals cannot float, which contrasts them with true planktonic organisms, such as Velella and the Portuguese Man o’ War, which are buoyant. Pseudoplankton are often found in the guts of filtering zooplankters.BOOK, Coral Reef Ecology, Yuri I., Sorokin, Springer Science & Business Media, 12 March 2013, 96, 9783642800467,books.google.com/books?id=hKvrCAAAQBAJ,

Tychoplankton

Tychoplankton are organisms, such as free-living or attached benthic organisms and other non-planktonic organisms, that are carried into the plankton through a disturbance of their benthic habitat, or by winds and currents.BOOK, Chapman, Michael J., Lynn, Margulis, Lynn Margulis, Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth,archive.org/details/fivekingdomsillu00marg_711, limited, 2009, Academic Press/Elsevier, Amsterdam, 978-0123736215, 566, [4th ed.]., This can occur by direct turbulence or by disruption of the substrate and subsequent entrainment in the water column.BOOK,archive.org/details/encyclopediabiol00simb, Encyclopedia of biological invasions, University of California Press, 2011, 978-0520264212, Simberloff, Daniel, Berkeley, 736, Rejmanek, Marcel, limited, Tychoplankton are, therefore, a primary subdivision for sorting planktonic organisms by duration of lifecycle spent in the plankton, as neither their entire lives nor particular reproductive portions are confined to planktonic existence.BOOK, Kennish, Michael J., Estuarine Research, Monitoring, and Resource Protection, 2004, CRC Press, Boca Raton, Fla., 978-0849319600, 194,www.crcpress.com/product/isbn/0849319609,www.crcpress.com/product/isbn/0849319609," title="archive.today/20130120014208www.crcpress.com/product/isbn/0849319609,">archive.today/20130120014208www.crcpress.com/product/isbn/0849319609, dead, 2013-01-20, Tychoplankton are sometimes called accidental plankton.

Mineralized plankton

{{See also|protist shells|biomineralization}}File:Diatom Helipelta metil.jpg|Diatoms have glass shells (frustules) and produce much of the world’s oxygen.File:Haeckel Spumellaria detail.png| The elaborate silica shells of microscopic marine radiolarians can eventually produce opal. File:Coccolithus pelagicus.jpg| Coccolithophores have chalk plates called coccoliths, and produced the Cliffs of Dover.File:Cwall99 lg.jpg| Planktonic algae bloom of coccolithophores off the southern coast of EnglandFile:Planktic Foraminifera of the northern Gulf of Mexico.jpg| Foraminiferans have calcium carbonate shells and produced the limestone in the Great Pyramids.{{Clear}}

Distribution

(File:Plankton satellite image.jpg|thumb|400px|right| {{center|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.}})Apart from aeroplankton, plankton inhabits oceans, seas, lakes and ponds. Local abundance varies horizontally, vertically and seasonally. The primary cause of this variability is the availability of light. All plankton ecosystems are driven by the input of solar energy (but see chemosynthesis), confining primary production to surface waters, and to geographical regions and seasons having abundant light.A secondary variable is nutrient availability. Although large areas of the tropical and sub-tropical oceans have abundant light, they experience relatively low primary production because they offer limited nutrients such as nitrate, phosphate and silicate. This results from large-scale ocean circulation and water column stratification. In such regions, primary production usually occurs at greater depth, although at a reduced level (because of reduced light).Despite significant macronutrient concentrations, some ocean regions are unproductive (so-called HNLC regions).MARTIN > FIRST = J.H. YEAR=1988, Iron-deficiency limits phytoplankton growth in the Northeast Pacific Subarctic volume=331, 341–343 issue=6154, 1988Natur.331..341M, 4325562, The micronutrient iron is deficient in these regions, and adding it can lead to the formation of phytoplankton algal blooms.BOYD > FIRST1 = P.W., 2000, A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by fertilization volume=407, 695–702 pmid = 11048709 first2 = AJ first3 = CS first4 = ER first5 = T first6 = R first7 = DC first8 = AR first9 = KO, 6805 bibcode = 2000Natur.407..695B, 4368261, Iron primarily reaches the ocean through the deposition of dust on the sea surface. Paradoxically, oceanic areas adjacent to unproductive, arid land thus typically have abundant phytoplankton (e.g., the eastern Atlantic Ocean, where trade winds bring dust from the Sahara Desert in north Africa).While plankton are most abundant in surface waters, they live throughout the water column. At depths where no primary production occurs, zooplankton and bacterioplankton instead consume organic material sinking from more productive surface waters above. This flux of sinking material, so-called marine snow, can be especially high following the termination of spring blooms.The local distribution of plankton can be affected by wind-driven Langmuir circulation and the biological effects of this physical process.

Ecological significance

Food chain

{{see also|marine food web}}Aside from representing the bottom few levels of a food chain that supports commercially important fisheries, plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements, including the ocean’s carbon cycle.JOURNAL, Falkowski, Paul G., 1994,marine.calpoly.edu/Needles/SPRING%2009/papers/2-Falkowski.pdf, The role of phytoplankton photosynthesis in global biogeochemical cycles, Photosynthesis Research, 39, 3, 235–258, 10.1007/BF00014586, 24311124, 12129871, {{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes }} Fish larvae mainly eat zooplankton, which in turn eat phytoplanktonJOURNAL, James, Alex, Pitchford, Jonathan W., Brindley, John, 2003-02-01, The relationship between plankton blooms, the hatching of fish larvae, and recruitment,www.sciencedirect.com/science/article/pii/S0304380002003113, Ecological Modelling, en, 160, 1, 77–90, 10.1016/S0304-3800(02)00311-3, 0304-3800,

Carbon cycle

{{see also|ocean carbon cycle|biological pump}}Primarily by grazing on phytoplankton, zooplankton provide carbon to the planktic foodweb, either respiring it to provide metabolic energy, or upon death as biomass or detritus. Organic material tends to be denser than seawater, so it sinks into open ocean ecosystems away from the coastlines, transporting carbon along with it. This process, called the biological pump, is one reason that oceans constitute the largest carbon sink on Earth. However, it has been shown to be influenced by increments of temperature.JOURNAL, Sarmento, H., Montoya, JM., Vázquez-Domínguez, E., Vaqué, D., Gasol, JM., 2010, Warming effects on marine microbial food web processes: how far can we go when it comes to predictions?, 2880134, Philosophical Transactions of the Royal Society B: Biological Sciences, 365, 1549, 2137–2149, 10.1098/rstb.2010.0045, 20513721, JOURNAL, Vázquez-Domínguez, E., Vaqué, D., Gasol, JM., 2007, Ocean warming enhances respiration and carbon demand of coastal microbial plankton., Global Change Biology, 13, 7, 1327–1334, 10.1111/j.1365-2486.2007.01377.x, 2007GCBio..13.1327V, 10261/15731, 8721854, free, JOURNAL, Vázquez-Domínguez, E., Vaqué, D., Gasol, JM., 2012, Temperature effects on the heterotrophic bacteria, heterotrophic nanoflagellates, and microbial top predators of NW Mediterranean., Aquatic Microbial Ecology, 67, 2, 107–121, 10.3354/ame01583, free, 10261/95626, free, JOURNAL, Mazuecos, E., Arístegui, J., Vázquez-Domínguez, E., Ortega-Retuerta, E., Gasol, JM., Reche, I., 2012, Temperature control of microbial respiration and growth efficiency in the mesopelagic zone of the South Atlantic and Indian Oceans., Deep Sea Research Part I: Oceanographic Research Papers, 95, 2, 131–138, 10.3354/ame01583, free, 10261/95626, free, In 2019, a study indicated that at ongoing rates of seawater acidification, Antarctic phytoplanktons could become smaller and less effective at storing carbon before the end of the century.WEB,phys.org/news/2019-08-acid-oceans-plankton-fueling-faster.html, Acid oceans are shrinking plankton, fueling faster climate change, Petrou, Katherina, Nielsen, Daniel, 2019-08-27, phys.org, en-us, 2019-09-07, It might be possible to increase the ocean’s uptake of carbon dioxide ({{chem|C|O|2}}) generated through human activities by increasing plankton production through iron fertilization – introducing amounts of iron into the ocean. However, this technique may not be practical at a large scale. Ocean oxygen depletion and resultant methane production (caused by the excess production remineralising at depth) is one potential drawback.CHISHOLM >FIRST1 = S.W., 2001, Dis-crediting ocean fertilization volume=294, 5541doi= 10.1126/science.1065349, 11598285 first2 = PG first3 = JJ display-authors = 1, JOURNAL

Oxygen production

{{see also|oxygen cycle}}Phytoplankton absorb energy from the Sun and nutrients from the water to produce their own nourishment or energy. In the process of photosynthesis, phytoplankton release molecular oxygen ({{chem|O|2}}) into the water as a waste byproduct. It is estimated that about 50% of the world’s oxygen is produced via phytoplankton photosynthesis.NEWS, Roach, John,news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html,news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html," title="web.archive.org/web/20040608065449news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html,">web.archive.org/web/20040608065449news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html, dead, June 8, 2004, Source of Half Earth’s Oxygen Gets Little Credit, National Geographic News, June 7, 2004, 2016-04-04, The rest is produced via photosynthesis on land by plants. Furthermore, phytoplankton photosynthesis has controlled the atmospheric {{chem|C|O|2}}/{{chem|O|2}} balance since the early Precambrian Eon.JOURNAL, Primary production, isotopes, extinctions and the atmosphere, Palaeogeography, Palaeoclimatology, Palaeoecology, April 1968, Tappan, Helen, 4, 3, 187–210, 10.1016/0031-0182(68)90047-3, 1968PPP.....4..187T,

Absorption efficiency

{{see also|biological pump}}The absorption efficiency (AE) of plankton is the proportion of food absorbed by the plankton that determines how available the consumed organic materials are in meeting the required physiological demands.JOURNAL, 10.1146/annurev-marine-010814-015924, Zooplankton and the Ocean Carbon Cycle, 2017, Steinberg, Deborah K., Landry, Michael R., Annual Review of Marine Science, 9, 413–444, 27814033, 2017ARMS....9..413S, Depending on the feeding rate and prey composition, variations in absorption efficiency may lead to variations in fecal pellet production, and thus regulates how much organic material is recycled back to the marine environment. Low feeding rates typically lead to high absorption efficiency and small, dense pellets, while high feeding rates typically lead to low absorption efficiency and larger pellets with more organic content. Another contributing factor to dissolved organic matter (DOM) release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon is loss from zooplankton in the form of respired {{CO2}}. The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more “sloppily”, that is more biomatter is released through inefficient consumption.JOURNAL, 10.1093/plankt/fbh147, Sloppy feeding in marine copepods: Prey-size-dependent production of dissolved organic carbon, 2004, Moller, E. F., Journal of Plankton Research, 27, 27–35, free, JOURNAL, 10.4319/lo.2007.52.1.0079, Production of dissolved organic carbon by sloppy feeding in the copepods Acartia tonsa, Centropages typicus, and Temora longicornis, 2007, Møller, Eva Friis, Limnology and Oceanography, 52, 1, 79–84, 2007LimOc..52...79M, free, There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon (DOC) and ammonium than omnivorous diets.JOURNAL, 10.3354/ame033279, Fate of organic carbon released from decomposing copepod fecal pellets in relation to bacterial production and ectoenzymatic activity, 2003, Thor, P., Dam, HG, Rogers, DR, Aquatic Microbial Ecology, 33, 279–288, free,

Biomass variability

The growth of phytoplankton populations is dependent on light levels and nutrient availability. The chief factor limiting growth varies from region to region in the world’s oceans. On a broad scale, growth of phytoplankton in the oligotrophic tropical and subtropical gyres is generally limited by nutrient supply, while light often limits phytoplankton growth in subarctic gyres. Environmental variability at multiple scales influences the nutrient and light available for phytoplankton, and as these organisms form the base of the marine food web, this variability in phytoplankton growth influences higher trophic levels. For example, at interannual scales phytoplankton levels temporarily plummet during El Niño periods, influencing populations of zooplankton, fishes, sea birds, and marine mammals.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 impacts on future phytoplankton productivity.JOURNAL, Steinacher, M., etal, 2010, Projected 21st century decrease in marine productivity: a multi-model analysis, Biogeosciences, 7, 3, 979–1005, 10.5194/bg-7-979-2010, 2010BGeo....7..979S, free, 11858/00-001M-0000-0011-F69E-5, free, Additionally, changes in the mortality of phytoplankton due to rates of zooplankton grazing may be significant.(File:Cycling of marine phytoplankton.png|thumb|upright=1.8|left| {{center|Marine phytoplankton cycling throughout water column}})File:Amphipodredkils.jpg|thumb|upright=1.2| Amphipod with curved exoskeletonexoskeleton{{clear}}

Plankton diversity

File: Pelagibacter.jpg|Pelagibacter ubique, the most common bacteria in the ocean, plays a major role in global carbon cyclesFile:Prochlorococcus marinus (cropped).jpg|The tiny cyanobacterium Prochlorococcus is a major contributor to atmospheric oxygenFile:Noctiluca scintillans varias.jpg|The sea sparkle dinoflagellate glows in the night to produce the milky seas effectFile:Copepodkils.jpg|Copepod from Antarctica, a translucent ovoid animal with two long antennaeFile:Clupeaharenguslarvaeinsitukils.jpg|Herring larva imaged with the remains of the yolk and the long gut visible in the transparent animalFile:Icefishuk.jpg|Icefish larvae from Antarctica have no haemoglobinFile:Mnemiopsis leidyi 2.jpg|The sea walnut ctenophore has a transient anus which forms only when it needs to defecateMAGAZINE, Animal with an anus that comes and goes could reveal how ours evolved, Michael Le Page, New Scientist,www.newscientist.com/article/2195656-animal-with-an-anus-that-comes-and-goes-could-reveal-how-ours-evolved/, March 2019, File:LeptocephalusConger.jpg|Eel larva drifting with the gulf streamFile:Krill666.jpg|Antarctic krill, probably the largest biomass of a single species on the planetFile:Dinoflagellates and a tintinnid ciliate.jpg|Microzooplankton are major grazers of the plankton: two dinoflagellates and a tintinnid ciliate.File:Sargassum on the beach, Cuba.JPG|Sargassum seaweed drifts with currents using air bladders to stay afloatFile:Plankton creates sea foam 2.jpg|Planktonic sea foam bubbles with image of photographerFile:Janthina.jpg|Macroplankton: a Janthina janthina snail (with bubble float) cast up onto a beach in Maui{{clear}}

Planktonic relationships

Fish & planktonZooplankton are the initial prey item for almost all fish larvae as they switch from their yolk sacs to external feeding. Fish rely on the density and distribution of zooplankton to match that of new larvae, which can otherwise starve. Natural factors (e.g., current variations, temperature changes) and man-made factors (e.g. river dams, ocean acidification, rising temperatures) can strongly affect zooplankton, which can in turn strongly affect larval survival, and therefore breeding success.It’s been shown that plankton can be patchy in marine environments where there aren’t significant fish populations and additionally, where fish are abundant, zooplankton dynamics are influenced by the fish predation rate in their environment. Depending on the predation rate, they could express regular or chaotic behavior.JOURNAL, Medvinsky, Alexander B., Tikhonova, Irene A., Aliev, Rubin R., Li, Bai-Lian, Lin, Zhen-Shan, Malchow, Horst, 2001-07-26, Patchy environment as a factor of complex plankton dynamics,link.aps.org/doi/10.1103/PhysRevE.64.021915, Physical Review E, en, 64, 2, 021915, 10.1103/PhysRevE.64.021915, 11497628, 2001PhRvE..64b1915M, 1063-651X, A negative effect that fish larvae can have on planktonic algal blooms is that the larvae will prolong the blooming event by diminishing available zooplankton numbers; this in turn permits excessive phytoplankton growth allowing the bloom to flourish .The importance of both phytoplankton and zooplankton is also well-recognized in extensive and semi-intensive pond fish farming. Plankton population-based pond management strategies for fish rearing have been practiced by traditional fish farmers for decades, illustrating the importance of plankton even in man-made environments.Whales & planktonOf all animal fecal matter, it is whale feces that is the ‘trophy’ in terms of increasing nutrient availability. Phytoplankton are the powerhouse of open ocean primary production and they can acquire many nutrients from whale feces.WEB, whale poop and phytoplankton, fighting climate change,www.ifaw.org/journal/whale-poop-phytoplankton-climate-change, 2022-03-29, IFAW, en-US, In the marine food web, phytoplankton are at the base of the food web and are consumed by zooplankton & krill, which are preyed upon by larger and larger marine organisms, including whales, so it can be said that whale poop fuels the entire food web.

Humans & plankton

Plankton have many direct and indirect effects on humans.Around 70% of the oxygen in the atmosphere is produced in the oceans from phytoplankton performing photosynthesis, meaning that the majority of the oxygen available for us and other organisms that respire aerobically is produced by plankton.JOURNAL, Sekerci, Yadigar, Petrovskii, Sergei, 2015-12-01, Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change,doi.org/10.1007/s11538-015-0126-0, Bulletin of Mathematical Biology, en, 77, 12, 2325–2353, 10.1007/s11538-015-0126-0, 26607949, 8637912, 1522-9602, 2381/36058, free, Plankton also make up the base of the marine food web, providing food for all the trophic levels above. Recent studies have analyzed the marine food web to see if the system runs on a top-down or bottom-up approach. Essentially, this research is focused on understanding whether changes in the food web are driven by nutrients at the bottom of the food web or predators at the top. The general conclusion is that the bottom-up approach seemed to be more predictive of food web behavior.JOURNAL, Frederiksen, Morten, Edwards, Martin, Richardson, Anthony J., Halliday, Nicholas C., Wanless, Sarah, November 2006, From plankton to top predators: bottom-up control of a marine food web across four trophic levels,onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2006.01148.x, Journal of Animal Ecology, en, 75, 6, 1259–1268, 10.1111/j.1365-2656.2006.01148.x, 17032358, 0021-8790, This indicates that plankton have more sway in determining the success of the primary consumer species that prey on them than do the secondary consumers that prey on the primary consumers.In some cases, plankton act as an intermediate host for deadly parasites in humans. One such case is that of cholera, an infection caused by several strains of Vibrio cholerae. These species have been shown to have a symbiotic relationship with chitinous zooplankton species like copepods. These bacteria benefit not only from the food provided by the chiton from the zooplankton, but also from the protection from acidic environments. Once the copepods have been ingested by a human host, the chitinous exterior protects the bacteria from the stomach acids in the stomach and proceed to the intestines. Once there, the bacteria bind with the surface of the small intestine and the host will start developing symptoms, including extreme diarrhea, within five days.JOURNAL, Lipp, Erin K., Huq, Anwar, Colwell, Rita R., October 2002, Effects of Global Climate on Infectious Disease: the Cholera Model, Clinical Microbiology Reviews, en, 15, 4, 757–770, 10.1128/CMR.15.4.757-770.2002, 0893-8512, 126864, 12364378,

See also

• Aeroplankton
• Gelatinous zooplankton
• Ichthyoplankton
• Nekton
• Paradox of the plankton
• Seston
• Veliger

References

{{reflist}}

Further reading

• Kirby, Richard R. (2010). Ocean Drifters: A Secret World Beneath the Waves. Studio Cactus Ltd, UK. {{ISBN|978-1-904239-10-9}}.
• Dusenbery, David B. (2009). Living at Micro Scale: The Unexpected Physics of Being Small. Harvard University Press, Cambridge, Massachusetts {{ISBN|978-0-674-03116-6}}.
• Kiørboe, Thomas (2008). A Mechanistic Approach to Plankton Ecology. Princeton University Press, Princeton, N.J. {{ISBN|978-0-691-13422-2}}.
• Dolan, J.R., Agatha, S., Coats, D.W., Montagnes, D.J.S., Stocker, D.K., eds. (2013).Biology and Ecology of Tintinnid Ciliates: Models for Marine Plankton. Wiley-Blackwell, Oxford, UK {{ISBN|978-0-470-67151-1}}.

External links

{{wiktionary}}{{commons|Plankton}}{{EB1911 Poster|Plankton}}

• Ocean Drifters – Short film narrated by David Attenborough about the varied roles of plankton
• Plankton Chronicles {{Webarchive|url=https://web.archive.org/web/20200728100833planktonchronicles.org/en/ |date=2020-07-28 }} – Short documentary films and photos
• COPEPOD: The Global Plankton Database – Global coverage database of zooplankton biomass and abundance data
• PlanktonNet – Taxonomic database of images of plankton species
• www.tafi.org.au/zooplankton/" title="web.archive.org/web/20080530005405www.tafi.org.au/zooplankton/">Guide to the marine zooplankton of south-eastern Australia – Tasmanian Aquaculture and Fisheries Institute
• www.sahfos.ac.uk/" title="web.archive.org/web/20090725052255www.sahfos.ac.uk/">Sir Alister Hardy Foundation for Ocean Science – Continuous Plankton Recorder Survey
• imos.org.au/auscpr.html" title="web.archive.org/web/20081201125235imos.org.au/auscpr.html">Australian Continuous Plankton Recorder Project – Integrated Marine Observing System
• Sea Drifters – BBC Audio slideshow
• weblink – Images of planktonic microorganisms
• aslo.org/lo/toc/vol_19/issue_2/0360b.pdf" title="web.archive.org/web/20170327115015aslo.org/lo/toc/vol_19/issue_2/0360b.pdf">Plankton, planktic, planktonic – Essays on nomenclature
• Journal of Plankton Research{{dead link|date=November 2023|bot=medic}}{{cbignore|bot=medic}} – Scientific periodical devoted to plankton

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