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139-408: Coccolithophores , or coccolithophorids , are single-celled organisms which are part of the phytoplankton , the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdom Protista , according to Robert Whittaker 's five-kingdom system , or clade Hacrobia , according to a newer biological classification system. Within

278-407: A calcium carbonate shell called a coccosphere . However, the reasons they calcify remain elusive. One key function may be that the coccosphere offers protection against microzooplankton predation, which is one of the main causes of phytoplankton death in the ocean. Coccolithophores are ecologically important, and biogeochemically they play significant roles in the marine biological pump and

417-595: A in austral spring and summer in the Southern Ocean, plays an important role in climate fluctuations, accounting for over 60% of the Southern Ocean area (30–60° S). The region between 30° and 50° S has the highest uptake of anthropogenic carbon dioxide (CO 2 ) alongside the North Atlantic and North Pacific oceans. Recent studies show that climate change has direct and indirect impacts on Coccolithophore distribution and productivity. They will inevitably be affected by

556-549: A 2012 study estimated that the overall effect of coccolithophores on the increase in radiative forcing of the ocean is less than that from anthropogenic factors. Therefore, the overall result of large blooms of coccolithophores is a decrease in water column productivity, rather than a contribution to global warming. Their predators include the common predators of all phytoplankton including small fish, zooplankton, and shellfish larvae. Viruses specific to this species have been isolated from several locations worldwide and appear to play

695-508: A better view of their global distribution. The term phytoplankton encompasses all photoautotrophic microorganisms in aquatic food webs . However, unlike terrestrial communities , where most autotrophs are plants , phytoplankton are a diverse group, incorporating protistan eukaryotes and both eubacterial and archaebacterial prokaryotes . There are about 5,000 known species of marine phytoplankton. How such diversity evolved despite scarce resources (restricting niche differentiation )

834-435: A body of water or cultured, though the former method is seldom used. Phytoplankton is used as a foodstock for the production of rotifers , which are in turn used to feed other organisms. Phytoplankton is also used to feed many varieties of aquacultured molluscs , including pearl oysters and giant clams . A 2018 study estimated the nutritional value of natural phytoplankton in terms of carbohydrate, protein and lipid across

973-583: A calcium carbonate shell called a 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). 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. One of

1112-422: A coccosphere seems to be a protection against predators or viruses. Viral infection is an important cause of phytoplankton death in the oceans, and it has recently been shown that calcification can influence the interaction between a coccolithophore and its virus. The major predators of marine phytoplankton are microzooplankton like ciliates and dinoflagellates . These are estimated to consume about two-thirds of

1251-525: A culture medium. This water must be sterilized , usually by either high temperatures in an autoclave or by exposure to ultraviolet radiation , to prevent biological contamination of the culture. Various fertilizers are added to the culture medium to facilitate the growth of plankton. A culture must be aerated or agitated in some way to keep plankton suspended, as well as to provide dissolved carbon dioxide for photosynthesis . In addition to constant aeration, most cultures are manually mixed or stirred on

1390-449: A decrease in nutrient flow to lower levels of the ocean. The most abundant species of coccolithophore, Emiliania huxleyi , belongs to the order Isochrysidales and family Noëlaerhabdaceae . It is found in temperate , subtropical , and tropical oceans. This makes E. huxleyi an important part of the planktonic base of a large proportion of marine food webs . It is also the fastest growing coccolithophore in laboratory cultures. It

1529-553: A form of phagocytosis . While protozoa reproduce mainly asexually, some protozoa are capable of sexual reproduction. Protozoa with sexual capability include the pathogenic species Plasmodium falciparum , Toxoplasma gondii , Trypanosoma brucei , Giardia duodenalis and Leishmania species. Ciliophora , or ciliates, are a group of protists that utilize cilia for locomotion. Examples include Paramecium , Stentors , and Vorticella . Ciliates are widely abundant in almost all environments where water can be found, and

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1668-425: A functional or vestigial haptonema is also present. This structure, which is unique to haptophytes , coils and uncoils in response to environmental stimuli. Although poorly understood, it has been proposed to be involved in prey capture. The complex life cycle of coccolithophores is known as a haplodiplontic life cycle , and is characterized by an alternation of both asexual and sexual phases. The asexual phase

1807-778: A fundamental principle to understand marine ecology, biogeochemistry and phytoplankton evolution. However, the Redfield ratio is not a universal value and it may diverge due to the changes in exogenous nutrient delivery and microbial metabolisms in the ocean, such as nitrogen fixation , denitrification and anammox . The dynamic stoichiometry shown in unicellular algae reflects their capability to store nutrients in an internal pool, shift between enzymes with various nutrient requirements and alter osmolyte composition. Different cellular components have their own unique stoichiometry characteristics, for instance, resource (light or nutrients) acquisition machinery such as proteins and chlorophyll contain

1946-484: A greater range of genetic diversity by combining the DNA of the parents followed by recombination . Metabolic functions in eukaryotes are more specialized as well by sectioning specific processes into organelles. The endosymbiotic theory holds that mitochondria and chloroplasts have bacterial origins. Both organelles contain their own sets of DNA and have bacteria-like ribosomes. It is likely that modern mitochondria were once

2085-495: A high concentration of nitrogen but low in phosphorus. Meanwhile, growth machinery such as ribosomal RNA contains high nitrogen and phosphorus concentrations. Based on allocation of resources, phytoplankton is classified into three different growth strategies, namely survivalist, bloomer and generalist. Survivalist phytoplankton has a high ratio of N:P (>30) and contains an abundance of resource-acquisition machinery to sustain growth under scarce resources. Bloomer phytoplankton has

2224-414: A higher albedo , and 2) there is induced photoinhibition , meaning photosythetic production is diminished due to an excess of light. In case 1), a high concentration of coccoliths leads to a simultaneous increase in surface water temperature and decrease in the temperature of deeper waters. This results in more stratification in the water column and a decrease in the vertical mixing of nutrients. However,

2363-476: A hypothetical gain in competitiveness due to altered carbonate chemistry conditions would not automatically lead to dinoflagellate dominance because a huge number of factors other than carbonate chemistry have an influence on species composition as well. Currently, the evidence supporting or refuting a protective function of the coccosphere against predation is limited. Some researchers found that overall microzooplankton predation rates were reduced during blooms of

2502-565: A low N:P ratio (<10), contains a high proportion of growth machinery, and is adapted to exponential growth. Generalist phytoplankton has similar N:P to the Redfield ratio and contain relatively equal resource-acquisition and growth machinery. The NAAMES study was a five-year scientific research program conducted between 2015 and 2019 by scientists from Oregon State University and NASA to investigated aspects of phytoplankton dynamics in ocean ecosystems, and how such dynamics influence atmospheric aerosols , clouds, and climate (NAAMES stands for

2641-560: A major role in spring bloom dynamics. No environmental evidence of coccolithophore toxicity has been reported, but they belong to the class Prymnesiophyceae which contain orders with toxic species. Toxic species have been found in the genera Prymnesium Massart and Chrysochromulina Lackey. Members of the genus Prymnesium have been found to produce haemolytic compounds, the agent responsible for toxicity. Some of these toxic species are responsible for large fish kills and can be accumulated in organisms such as shellfish; transferring it through

2780-501: A nucleus, or the Golgi apparatus. Prokaryotic cells probably transitioned into eukaryotic cells between 2.0 and 1.4 billion years ago. This was an important step in evolution. In contrast to prokaryotes, eukaryotes reproduce by using mitosis and meiosis . Sex appears to be a ubiquitous and ancient, and inherent attribute of eukaryotic life. Meiosis, a true sexual process, allows for efficient recombinational repair of DNA damage and

2919-435: A nutritional supplement for captive invertebrates in aquaria . Culture sizes range from small-scale laboratory cultures of less than 1L to several tens of thousands of litres for commercial aquaculture. Regardless of the size of the culture, certain conditions must be provided for efficient growth of plankton. The majority of cultured plankton is marine, and seawater of a specific gravity of 1.010 to 1.026 may be used as

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3058-422: A process called budding , where most of the cytoplasm is held by the mother cell. Saccharomyces cerevisiae ferments carbohydrates into carbon dioxide and alcohol, and is used in the making of beer and bread. S. cerevisiae is also an important model organism, since it is a eukaryotic organism that is easy to grow. It has been used to research cancer and neurodegenerative diseases as well as to understand

3197-413: A protective shell of coccoliths , calcified scales which make up its exoskeleton or coccosphere . The coccoliths are created inside the coccolithophore cell and while some species maintain a single layer throughout life only producing new coccoliths as the cell grows, others continually produce and shed coccoliths. The primary constituent of coccoliths is calcium carbonate, or chalk . Calcium carbonate

3336-491: A regular basis. Light must be provided for the growth of phytoplankton. The colour temperature of illumination should be approximately 6,500 K, but values from 4,000 K to upwards of 20,000 K have been used successfully. The duration of light exposure should be approximately 16 hours daily; this is the most efficient artificial day length. Marine phytoplankton perform half of the global photosynthetic CO 2 fixation (net global primary production of ~50 Pg C per year) and half of

3475-432: A sexual process referred to as natural genetic transformation . Transformation is a bacterial process for transferring DNA from one cell to another, and is apparently an adaptation for repairing DNA damage in the recipient cell. In addition, plasmids can be exchanged through the use of a pilus in a process known as conjugation . The photosynthetic cyanobacteria are arguably the most successful bacteria, and changed

3614-406: A sharp increase in the population of coccolithophores. Coccolithophores are one of the more abundant primary producers in the ocean. As such, they are a large contributor to the primary productivity of the tropical and subtropical oceans, however, exactly how much has yet to have been recorded. The ratio between the concentrations of nitrogen , phosphorus and silicate in particular areas of

3753-429: A smaller cell radius and lower cell volume than other types of phytoplankton. Giant DNA-containing viruses are known to lytically infect coccolithophores, particularly E. huxleyi . These viruses, known as E. huxleyi viruses (EhVs), appear to infect the coccosphere coated diploid phase of the life cycle almost exclusively. It has been proposed that as the haploid organism is not infected and therefore not affected by

3892-493: A species increases rapidly under conditions favorable to growth can produce harmful algal blooms (HABs). Phytoplankton are a key food item in both aquaculture and mariculture . Both utilize phytoplankton as food for the animals being farmed. In mariculture, the phytoplankton is naturally occurring and is introduced into enclosures with the normal circulation of seawater. In aquaculture, phytoplankton must be obtained and introduced directly. The plankton can either be collected from

4031-592: A species similar to Rickettsia , with the parasitic ability to enter a cell. However, if the bacteria were capable of respiration, it would have been beneficial for the larger cell to allow the parasite to live in return for energy and detoxification of oxygen. Chloroplasts probably became symbionts through a similar set of events, and are most likely descendants of cyanobacteria. While not all eukaryotes have mitochondria or chloroplasts, mitochondria are found in most eukaryotes, and chloroplasts are found in all plants and algae. Photosynthesis and respiration are essentially

4170-440: A unicellular life-cycle stage. Gametes , for example, are reproductive unicells for multicellular organisms. Additionally, multicellularity appears to have evolved independently many times in the history of life. Some organisms are partially unicellular, like Dictyostelium discoideum . Additionally, unicellular organisms can be multinucleate , like Caulerpa , Plasmodium , and Myxogastria . Primitive protocells were

4309-413: Is a coccolithophore. Coccolithophores are single-celled phytoplankton that produce small calcium carbonate (CaCO 3 ) scales ( coccoliths ) which cover the cell surface in the form of a spherical coating, called a coccosphere . Many species are also mixotrophs , and are able to photosynthesise as well as ingest prey. Coccolithophores have been an integral part of marine plankton communities since

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4448-465: Is a notable exception). While almost all phytoplankton species are obligate photoautotrophs , there are some that are mixotrophic and other, non-pigmented species that are actually heterotrophic (the latter are often viewed as zooplankton ). Of these, the best known are dinoflagellate genera such as Noctiluca and Dinophysis , that obtain organic carbon by ingesting other organisms or detrital material. Phytoplankton live in

4587-414: Is a single cell with membrane bound organelles . Two large chloroplasts with brown pigment are located on either side of the cell and surround the nucleus , mitochondria , golgi apparatus , endoplasmic reticulum , and other organelles. Each cell also has two flagellar structures, which are involved not only in motility, but also in mitosis and formation of the cytoskeleton . In some species,

4726-970: Is compacted serve as valuable microfossils . Calcification , the biological production of calcium carbonate (CaCO 3 ), is a key process in the marine carbon cycle . Coccolithophores are the major planktonic group responsible for pelagic CaCO 3 production. The diagram on the right shows the energetic costs of coccolithophore calcification: The diagram on the left shows the benefits of coccolithophore calcification. (A) Accelerated photosynthesis includes CCM (1) and enhanced light uptake via scattering of scarce photons for deep-dwelling species (2). (B) Protection from photodamage includes sunshade protection from ultraviolet (UV) light and photosynthetic active radiation (PAR) (1) and energy dissipation under high-light conditions (2). (C) Armor protection includes protection against viral/bacterial infections (1) and grazing by selective (2) and nonselective (3) grazers. The degree by which calcification can adapt to ocean acidification

4865-500: Is declining, leading to higher light penetration and potentially more primary production; however, there are conflicting predictions for the effects of variable mixing patterns and changes in nutrient supply and for productivity trends in polar zones. The effect of human-caused climate change on phytoplankton biodiversity is not well understood. Should greenhouse gas emissions continue rising to high levels by 2100, some phytoplankton models predict an increase in species richness , or

5004-492: 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. Limitations in these metals can lead to co-limitations and shifts in phytoplankton community structure. Across large areas of

5143-889: Is evaluating the contributions of phytoplankton to carbon fixation and forecasting how this production may change in response to perturbations. Predicting the effects of climate change on primary productivity is complicated by phytoplankton bloom cycles that are affected by both bottom-up control (for example, availability of essential nutrients and vertical mixing) and top-down control (for example, grazing and viruses). Increases in solar radiation, temperature and freshwater inputs to surface waters strengthen ocean stratification and consequently reduce transport of nutrients from deep water to surface waters, which reduces primary productivity. Conversely, rising CO 2 levels can increase phytoplankton primary production, but only when nutrients are not limiting. Some studies indicate that overall global oceanic phytoplankton density has decreased in

5282-451: Is known as the haploid phase, while the sexual phase is known as the diploid phase. During the haploid phase, coccolithophores produce haploid cells through mitosis . These haploid cells can then divide further through mitosis or undergo sexual reproduction with other haploid cells. The resulting diploid cell goes through meiosis to produce haploid cells again, starting the cycle over. With coccolithophores, asexual reproduction by mitosis

5421-558: Is low in nutrient concentration, high in light intensity and penetration, and usually higher in temperature. The lower photic zone is high in nutrient concentration, low in light intensity and penetration and relatively cool. The middle photic zone is an area that contains the same values in between that of the lower and upper photic zones. The Great Calcite Belt of the Southern Ocean is a region of elevated summertime upper ocean calcite concentration derived from coccolithophores, despite

5560-425: Is of utmost importance to secondary producers such as copepods, fish and shrimp, because it determines the nutritional quality and influences energy flow through the marine food chains . Climate change may greatly restructure phytoplankton communities leading to cascading consequences for marine food webs , thereby altering the amount of carbon transported to the ocean interior. The figure gives an overview of

5699-416: Is possible in both phases of the life cycle, which is a contrast with most other organisms that have alternating life cycles. Both abiotic and biotic factors may affect the frequency with which each phase occurs. Coccolithophores reproduce asexually through binary fission. In this process the coccoliths from the parent cell are divided between the two daughter cells. There have been suggestions stating

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5838-443: Is possible within one year. Unraveling these fundamental constraints and the limits of adaptation should be a focus in future coccolithophore studies because knowing them is the key information required to understand to what extent the calcification response to carbonate chemistry perturbations can be compensated by evolution. Silicate- or cellulose-armored functional groups such as diatoms and dinoflagellates do not need to sustain

5977-447: Is predicted to co-occur with ocean acidification and warming, due to increased stratification of the water column and reduced mixing of nutrients from the deep water to the surface. The compartments influenced by phytoplankton include the atmospheric gas composition, inorganic nutrients, and trace element fluxes as well as the transfer and cycling of organic matter via biological processes (see figure). The photosynthetically fixed carbon

6116-489: Is presently unknown. Cell physiological examinations found the essential H efflux (stemming from the use of HCO 3 for intra-cellular calcification) to become more costly with ongoing ocean acidification as the electrochemical H inside-out gradient is reduced and passive proton outflow impeded. Adapted cells would have to activate proton channels more frequently, adjust their membrane potential , and/or lower their internal pH . Reduced intra-cellular pH would severely affect

6255-451: Is rapidly recycled and reused in the surface ocean, while a certain fraction of this biomass is exported as sinking particles to the deep ocean, where it is subject to ongoing transformation processes, e.g., remineralization. Phytoplankton contribute to not only a basic pelagic marine food web but also to the microbial loop. Phytoplankton are the base of the marine food web and because they do not rely on other organisms for food, they make up

6394-416: Is studied for the extensive blooms it forms in nutrient depleted waters after the reformation of the summer thermocline . and for its production of molecules known as alkenones that are commonly used by earth scientists as a means to estimate past sea surface temperatures . Coccolithophores (or coccolithophorids, from the adjective) form a group of about 200 phytoplankton species. They belong either to

6533-402: Is the cause of amebic dysentery. Entamoeba histolytica appears to be capable of meiosis . Unicellular algae are plant-like autotrophs and contain chlorophyll . They include groups that have both multicellular and unicellular species: Unicellular fungi include the yeasts . Fungi are found in most habitats, although most are found on land. Yeasts reproduce through mitosis, and many use

6672-415: Is transparent, so the organisms' photosynthetic activity is not compromised by encapsulation in a coccosphere. Coccoliths are produced by a biomineralization process known as coccolithogenesis. Generally, calcification of coccoliths occurs in the presence of light, and these scales are produced much more during the exponential phase of growth than the stationary phase. Although not yet entirely understood,

6811-471: Is unclear. In terms of numbers, the most important groups of phytoplankton include the diatoms , cyanobacteria and dinoflagellates , although many other groups of algae are represented. One group, the coccolithophorids , is responsible (in part) for the release of significant amounts of dimethyl sulfide (DMS) into the atmosphere . DMS is oxidized to form sulfate which, in areas where ambient aerosol particle concentrations are low, can contribute to

6950-414: Is widely accepted to affect the land-based fossil record . The coccolithophorids help in regulating the temperature of the oceans. They thrive in warm seas and release dimethyl sulfide (DMS) into the air whose nuclei help to produce thicker clouds to block the sun. When the oceans cool, the number of coccolithophorids decrease and the amount of clouds also decrease. When there are fewer clouds blocking

7089-520: The Jurassic . Today, coccolithophores contribute ~1–10% to inorganic carbon fixation (calcification) to total carbon fixation (calcification plus photosynthesis) in the surface ocean and ~50% to pelagic CaCO 3 sediments. Their calcareous shell increases the sinking velocity of photosynthetically fixed CO 2 into the deep ocean by ballasting organic matter. At the same time, the biogenic precipitation of calcium carbonate during coccolith formation reduces

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7228-453: The White Cliffs of Dover , and of other similar rocks in many other parts of the world. At the present day sedimented coccoliths are a major component of the calcareous oozes that cover up to 35% of the ocean floor and is kilometres thick in places. Because of their abundance and wide geographic ranges, the coccoliths which make up the layers of this ooze and the chalky sediment formed as it

7367-423: The carbon cycle . Depending on habitat, they can produce up to 40 percent of the local marine primary production . They are of particular interest to those studying global climate change because, as ocean acidity increases, their coccoliths may become even more important as a carbon sink . Management strategies are being employed to prevent eutrophication -related coccolithophore blooms, as these blooms lead to

7506-449: The carbon cycle . The production of coccoliths requires the uptake of dissolved inorganic carbon and calcium. Calcium carbonate and carbon dioxide are produced from calcium and bicarbonate by the following chemical reaction: Because coccolithophores are photosynthetic organisms, they are able to use some of the CO 2 released in the calcification reaction for photosynthesis . However,

7645-531: The cell cycle . Furthermore, research using S. cerevisiae has played a central role in understanding the mechanism of meiotic recombination and the adaptive function of meiosis . Candida spp . are responsible for candidiasis , causing infections of the mouth and/or throat (known as thrush) and vagina (commonly called yeast infection). Most unicellular organisms are of microscopic size and are thus classified as microorganisms . However, some unicellular protists and bacteria are macroscopic and visible to

7784-449: The diatoms ). Most phytoplankton are too small to be individually seen with the unaided eye . However, when present in high enough numbers, some varieties may be noticeable as colored patches on the water surface due to the presence of chlorophyll within their cells and accessory pigments (such as phycobiliproteins or xanthophylls ) in some species. Phytoplankton are photosynthesizing microscopic protists and bacteria that inhabit

7923-422: The diatoms ). Many other organism groups formally named as phytoplankton, including coccolithophores and dinoflagellates , are now no longer included as they are not only phototrophic but can also eat. These organisms are now more correctly termed  mixoplankton . This recognition has important consequences for how we view the functioning of the planktonic food web. Phytoplankton obtain energy through

8062-470: The nucleoid . Most prokaryotes have a single, circular chromosome , which is in contrast to eukaryotes, which typically have linear chromosomes. Nutritionally, prokaryotes have the ability to utilize a wide range of organic and inorganic material for use in metabolism, including sulfur, cellulose, ammonia, or nitrite. Prokaryotes are relatively ubiquitous in the environment and some (known as extremophiles) thrive in extreme environments. Bacteria are one of

8201-449: 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 pigments which species-specifically enables them to absorb different wavelengths of the variable underwater light. This implies different species can use

8340-433: The process of photosynthesis and must therefore live in the well-lit surface layer (termed the euphotic zone ) of an ocean , sea , lake , or other body of water. Phytoplankton account for about half of all photosynthetic activity on Earth. Their cumulative energy fixation in carbon compounds ( primary production ) is the basis for the vast majority of oceanic and also many freshwater food webs ( chemosynthesis

8479-477: The white cliffs of Dover . Of particular interest are fossils dating back to the Palaeocene-Eocene Thermal Maximum 55 million years ago. This period is thought to correspond most directly to the current levels of CO 2 in the ocean. Finally, field evidence of coccolithophore fossils in rock were used to show that the deep-sea fossil record bears a rock record bias similar to the one that

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8618-494: The European-based CALMARO are monitoring the responses of coccolithophore populations to varying pH's and working to determine environmentally sound measures of control. Coccolith fossils are prominent and valuable calcareous microfossils . They are the largest global source of biogenic calcium carbonate, and significantly contribute to the global carbon cycle . They are the main constituent of chalk deposits such as

8757-454: The Hacrobia, the coccolithophores are in the phylum or division Haptophyta , class Prymnesiophyceae (or Coccolithophyceae ). Coccolithophores are almost exclusively marine , are photosynthetic and mixotrophic , and exist in large numbers throughout the sunlight zone of the ocean . Coccolithophores are the most productive calcifying organisms on the planet, covering themselves with

8896-517: The Indian Ocean, are not as well studied as other locations in the Pacific and Atlantic Oceans. It is also very hard to explain distributions due to multiple constantly changing factors involving the ocean's properties, such as coastal and equatorial upwelling , frontal systems, benthic environments, unique oceanic topography, and pockets of isolated high or low water temperatures. The upper photic zone

9035-542: The North Atlantic Aerosols and Marine Ecosystems Study). The study focused on the sub-arctic region of the North Atlantic Ocean, which is the site of one of Earth's largest recurring phytoplankton blooms. The long history of research in this location, as well as relative ease of accessibility, made the North Atlantic an ideal location to test prevailing scientific hypotheses in an effort to better understand

9174-796: The Pacific Ocean was in an area of the ocean considered the Central North Zone which is an area between 30 N and 5 N, composed of the North Equatorial Current and the Equatorial Countercurrent. These two currents move in opposite directions, east and west, allowing for a strong mixing of waters and allowing a large variety of species to populate the area. In the Atlantic Ocean, the most abundant species are E. huxleyi and Florisphaera profunda with smaller concentrations of

9313-525: The added weight of multiple layers of coccoliths allows the organism to sink to lower, more nutrient rich layers of the water and conversely, that coccoliths add buoyancy, stopping the cell from sinking to dangerous depths. Coccolith appendages have also been proposed to serve several functions, such as inhibiting grazing by zooplankton. Coccoliths are the main component of the Chalk , a Late Cretaceous rock formation which outcrops widely in southern England and forms

9452-476: The alga, this additional source of gas is then available to the Coccolithophore for photosynthesis. It has been suggested that they may provide a cell-wall like barrier to isolate intracellular chemistry from the marine environment. More specific, defensive properties of coccoliths may include protection from osmotic changes, chemical or mechanical shock, and short-wavelength light. It has also been proposed that

9591-404: The base of marine and freshwater food webs and are key players in the global carbon cycle . They account for about half of global photosynthetic activity and at least half of the oxygen production, despite amounting to only about 1% of the global plant biomass. Phytoplankton are very diverse, comprising photosynthesizing bacteria ( cyanobacteria ) and various unicellular protist groups (notably

9730-408: The basis of its size or shape and through chemical signals and may thus favor other prey that is available and not protected by coccoliths. Coccolithophores are spherical cells about 5–100 micrometres across, enclosed by calcareous plates called coccoliths , which are about 2–25 micrometres across. Each cell contains two brown chloroplasts which surround the nucleus . Enclosed in each coccosphere

9869-417: The biomineralization process is tightly regulated by calcium signaling . Calcite formation begins in the golgi complex where protein templates nucleate the formation of CaCO 3 crystals and complex acidic polysaccharides control the shape and growth of these crystals. As each scale is produced, it is exported in a Golgi-derived vesicle and added to the inner surface of the coccosphere. This means that

10008-652: The bottom of the ocean in the form of coccoliths and becomes part of sediment; thus, coccolithophores provide a sink for emitted carbon, mediating the effects of greenhouse gas emissions. Research also suggests that ocean acidification due to increasing concentrations of CO 2 in the atmosphere may affect the calcification machinery of coccolithophores. This may not only affect immediate events such as increases in population or coccolith production, but also may induce evolutionary adaptation of coccolithophore species over longer periods of time. For example, coccolithophores use H ion channels in to constantly pump H ions out of

10147-437: The calcification-related H efflux. Thus, they probably do not need to adapt in order to keep costs for the production of structural elements low. On the contrary, dinoflagellates (except for calcifying species; with generally inefficient CO 2 -fixing RuBisCO enzymes may even profit from chemical changes since photosynthetic carbon fixation as their source of structural elements in the form of cellulose should be facilitated by

10286-647: The cell during coccolith production. This allows them to avoid acidosis , as coccolith production would otherwise produce a toxic excess of H ions. When the function of these ion channels is disrupted, the coccolithophores stop the calcification process to avoid acidosis, thus forming a feedback loop . Low ocean alkalinity , impairs ion channel function and therefore places evolutionary selective pressure on coccolithophores and makes them (and other ocean calcifiers) vulnerable to ocean acidification. In 2008, field evidence indicating an increase in calcification of newly formed ocean sediments containing coccolithophores bolstered

10425-476: The cell. Heterococcoliths occur only in the diploid phase, have radial symmetry, and are composed of relatively few complex crystal units (fewer than 100). Although they are rare, combination coccospheres, which contain both holococcoliths and heterococcoliths, have been observed in the plankton recording coccolithophore life cycle transitions. Finally, the coccospheres of some species are highly modified with various appendages made of specialized coccoliths. While

10564-675: The cilia beat rhythmically in order to propel the organism. Many ciliates have trichocysts , which are spear-like organelles that can be discharged to catch prey, anchor themselves, or for defense. Ciliates are also capable of sexual reproduction, and utilize two nuclei unique to ciliates: a macronucleus for normal metabolic control and a separate micronucleus that undergoes meiosis. Examples of such ciliates are Paramecium and Tetrahymena that likely employ meiotic recombination for repairing DNA damage acquired under stressful conditions. The Amebozoa utilize pseudopodia and cytoplasmic flow to move in their environment. Entamoeba histolytica

10703-465: The coccolithophore Emiliania huxleyi , while others found high microzooplankton grazing rates on natural coccolithophore communities. In 2020, researchers found that in situ ingestion rates of microzooplankton on E. huxleyi did not differ significantly from those on similar sized non-calcifying phytoplankton. In laboratory experiments the heterotrophic dinoflagellate Oxyrrhis marina preferred calcified over non-calcified cells of E. huxleyi , which

10842-670: The coccolithoviruses and diploid organism. Coccolithophores are members of the clade Haptophyta , which is a sister clade to Centrohelida , which are both in Haptista . The oldest known coccolithophores are known from the Late Triassic, around the Norian - Rhaetian boundary. Diversity steadily increased over the course of the Mesozoic, reaching its apex during the Late Cretaceous . However, there

10981-430: The coccosphere prevents ingestion by the grazer. Instead, ingestion rates were dependent on the offered genotype of E. huxleyi. Altogether, these two studies suggest that the genotype has a strong influence on ingestion by the microzooplankton species, but if and how calcification protects coccolithophores from microzooplankton predation could not be fully clarified. Coccolithophores have both long and short term effects on

11120-472: The dinoflagellate shell, should rather be favored at high H concentrations because these usually coincide with high [CO 2 ]. Under these conditions dinoflagellates could down-regulate the energy-consuming operation of carbon concentrating mechanisms to fuel the production of organic source material for their shell. Therefore, a shift in carbonate chemistry conditions toward high [CO 2 ] may promote their competitiveness relative to coccolithophores. However, such

11259-627: The early atmosphere of the earth by oxygenating it. Stromatolites , structures made up of layers of calcium carbonate and trapped sediment left over from cyanobacteria and associated community bacteria, left behind extensive fossil records. The existence of stromatolites gives an excellent record as to the development of cyanobacteria, which are represented across the Archaean (4 billion to 2.5 billion years ago), Proterozoic (2.5 billion to 540 million years ago), and Phanerozoic (540 million years ago to present day) eons. Much of

11398-448: The early, harsh conditions that life was likely exposed to . Examples of these Archaean extremophiles are as follows: Methanogens are a significant subset of archaea and include many extremophiles, but are also ubiquitous in wetland environments as well as the ruminant and hindgut of animals. This process utilizes hydrogen to reduce carbon dioxide into methane, releasing energy into the usable form of adenosine triphosphate . They are

11537-457: The entire cellular machinery and require other processes (e.g. photosynthesis ) to co-adapt in order to keep H efflux alive. The obligatory H efflux associated with calcification may therefore pose a fundamental constraint on adaptation which may potentially explain why "calcification crisis" were possible during long-lasting (thousands of years) CO 2 perturbation events even though evolutionary adaption to changing carbonate chemistry conditions

11676-429: The exact function of the coccosphere is unclear, many potential functions have been proposed. Most obviously coccoliths may protect the phytoplankton from predators. It also appears that it helps them to create a more stable pH . During photosynthesis carbon dioxide is removed from the water, making it more basic. Also calcification removes carbon dioxide, but chemistry behind it leads to the opposite pH reaction; it makes

11815-413: The external environment. For example, an early RNA replicator ribozyme may have replicated other replicator ribozymes of different RNA sequences if not kept separate. Such hypothetic cells with an RNA genome instead of the usual DNA genome are called ' ribocells ' or 'ribocytes'. When amphiphiles like lipids are placed in water, the hydrophobic tails aggregate to form micelles and vesicles , with

11954-490: The first ever experimental data showing that an increase in ocean CO 2 concentration results in an increase in calcification of these organisms. Decreasing coccolith mass is related to both the increasing concentrations of CO 2 and decreasing concentrations of CO 2− 3 in the world's oceans. This lower calcification is assumed to put coccolithophores at ecological disadvantage. Some species like Calcidiscus leptoporus , however, are not affected in this way, while

12093-498: The first trophic level. Organisms such as zooplankton feed on these phytoplankton which are in turn fed on by other organisms and so forth until the fourth trophic level is reached with apex predators. Approximately 90% of total carbon is lost between trophic levels due to respiration, detritus, and dissolved organic matter. This makes the remineralization process and nutrient cycling performed by phytoplankton and bacteria important in maintaining efficiency. Phytoplankton blooms in which

12232-488: The food chain. In laboratory tests for toxicity members of the oceanic coccolithophore genera Emiliania, Gephyrocapsa, Calcidiscus and Coccolithus were shown to be non-toxic as were species of the coastal genus Hymenomonas , however several species of Pleurochrysis and Jomonlithus , both coastal genera were toxic to Artemia . Coccolithophorids are predominantly found as single, free-floating haploid or diploid cells. Most phytoplankton need sunlight and nutrients from

12371-765: The fossilized stromatolites of the world can be found in Western Australia . There, some of the oldest stromatolites have been found, some dating back to about 3,430 million years ago. Clonal aging occurs naturally in bacteria , and is apparently due to the accumulation of damage that can happen even in the absence of external stressors. Hydrothermal vents release heat and hydrogen sulfide , allowing extremophiles to survive using chemolithotrophic growth. Archaea are generally similar in appearance to bacteria, hence their original classification as bacteria, but have significant molecular differences most notably in their membrane structure and ribosomal RNA. By sequencing

12510-413: The genotype of E. huxleyi that was offered, rather than on their degree of calcification. In the same study, however, the authors found that predators which preyed on non-calcifying genotypes grew faster than those fed with calcified cells. In 2018, Strom et al. compared predation rates of the dinoflagellate Amphidinium longum on calcified relative to naked E. huxleyi prey and found no evidence that

12649-513: 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. 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

12788-484: The hydrophilic ends facing outwards. Primitive cells likely used self-assembling fatty-acid vesicles to separate chemical reactions and the environment. Because of their simplicity and ability to self-assemble in water, it is likely that these simple membranes predated other forms of early biological molecules. Prokaryotes lack membrane-bound organelles, such as mitochondria or a nucleus . Instead, most prokaryotes have an irregular region that contains DNA, known as

12927-435: The increasing temperatures and thermal stratification of the top layer of the ocean, since these are prime controls on their ecology, although it is not clear whether global warming would result in net increase or decrease of coccolithophores. As they are calcifying organisms, it has been suggested that ocean acidification due to increasing carbon dioxide could severely affect coccolithophores. Recent CO 2 increases have seen

13066-436: The key mediators of the biological pump . Understanding the response of phytoplankton to changing environmental conditions is a prerequisite to predict future atmospheric concentrations of CO 2 . Temperature, irradiance and nutrient concentrations, along with CO 2 are the chief environmental factors that influence the physiology and stoichiometry of phytoplankton. The stoichiometry or elemental composition of phytoplankton

13205-613: The kingdom Protista , according to Robert Whittaker 's Five kingdom classification , or clade Hacrobia , according to the newer biological classification system. Within the Hacrobia, the coccolithophores are in the phylum or division Haptophyta , class Prymnesiophyceae (or Coccolithophyceae ). Coccolithophores are distinguished by special calcium carbonate plates (or scales) of uncertain function called coccoliths , which are also important microfossils . However, there are Prymnesiophyceae species lacking coccoliths (e.g. in genus Prymnesium ), so not every member of Prymnesiophyceae

13344-440: The kingdom Protozoa: Euglenozoa , Amoebozoa , Choanozoa sensu Cavalier-Smith , Loukozoa , Percolozoa , Microsporidia and Sulcozoa . Protozoa, like plants and animals, can be considered heterotrophs or autotrophs. Autotrophs like Euglena are capable of producing their energy using photosynthesis, while heterotrophic protozoa consume food by either funneling it through a mouth-like gullet or engulfing it with pseudopods,

13483-500: The life cycle of coccolithophores occur seasonally, where more nutrition is available in warmer seasons and less is available in cooler seasons. This type of life cycle is known as a complex heteromorphic life cycle. Coccolithophores occur throughout the world's oceans. Their distribution varies vertically by stratified layers in the ocean and geographically by different temporal zones. While most modern coccolithophores can be located in their associated stratified oligotrophic conditions,

13622-501: The life cycle of different coccolithophore species, there is often alternation between a motile, haploid phase, and a non-motile diploid phase. In both phases, the organism's dispersal is largely due to ocean currents and circulation patterns. Within the Pacific Ocean, approximately 90 species have been identified with six separate zones relating to different Pacific currents that contain unique groupings of different species of coccolithophores. The highest diversity of coccolithophores in

13761-493: The many food chains 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 whales . The El Niño-Southern Oscillation (ENSO) cycles in the Equatorial Pacific area can affect phytoplankton. Biochemical and physical changes during ENSO cycles modify the phytoplankton community structure. Also, changes in

13900-592: The more dominant phytoplankton and reflect a larger portion of the biomass . In the early twentieth century, Alfred C. Redfield found the similarity of the phytoplankton's elemental composition to the major dissolved nutrients in the deep ocean. Redfield proposed that the ratio of carbon to nitrogen to phosphorus (106:16:1) in the ocean was controlled by the phytoplankton's requirements, as phytoplankton subsequently release nitrogen and phosphorus as they are remineralized. This so-called " Redfield ratio " in describing stoichiometry of phytoplankton and seawater has become

14039-472: The most abundant areas of coccolithophores where there is the highest species diversity are located in subtropical zones with a temperate climate. While water temperature and the amount of light intensity entering the water's surface are the more influential factors in determining where species are located, the ocean currents also can determine the location where certain species of coccolithophores are found. Although motility and colony formation vary according to

14178-527: The most abundant coccolithophore species, E. huxleyi might be (study results are mixed). Also, highly calcified coccolithophorids have been found in conditions of low CaCO 3 saturation contrary to predictions. Understanding the effects of increasing ocean acidification on coccolithophore species is absolutely essential to predicting the future chemical composition of the ocean, particularly its carbonate chemistry. Viable conservation and management measures will come from future research in this area. Groups like

14317-421: The most inexpensive armor under all circumstances because diatoms typically outcompete all other groups when silicate is available. The coccosphere is relatively inexpensive under sufficient [CO 2 ], high [HCO 3 ], and low [H] because the substrate is saturating and protons are easily released into seawater. In contrast, the construction of thecal elements, which are organic ( cellulose ) plates that constitute

14456-440: The most recently produced coccoliths may lie beneath older coccoliths. Depending upon the phytoplankton's stage in the life cycle, two different types of coccoliths may be formed. Holococcoliths are produced only in the haploid phase, lack radial symmetry, and are composed of anywhere from hundreds to thousands of similar minute (ca 0.1 μm) rhombic calcite crystals. These crystals are thought to form at least partially outside

14595-604: The naked eye. Examples include: Phytoplankton Phytoplankton ( / ˌ f aɪ t oʊ ˈ p l æ ŋ k t ə n / ) are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems . The name comes from the Greek words φυτόν ( phyton ), meaning ' plant ', and πλαγκτός ( planktos ), meaning 'wanderer' or 'drifter'. Phytoplankton obtain their energy through photosynthesis , as trees and other plants do on land. This means phytoplankton must have light from

14734-494: The number of different species within a given area. This increase in plankton diversity is traced to warming ocean temperatures. In addition to species richness changes, the locations where phytoplankton are distributed are expected to shift towards the Earth's poles. Such movement may disrupt ecosystems, because phytoplankton are consumed by zooplankton, which in turn sustain fisheries. This shift in phytoplankton location may also diminish

14873-468: The ocean acidification-associated CO 2 fertilization. Under the assumption that any form of shell/exoskeleton protects phytoplankton against predation non-calcareous armors may be the preferable solution to realize protection in a future ocean. The diagram on the right is a representation of how the comparative energetic effort for armor construction in diatoms, dinoflagellates and coccolithophores appear to operate. The frustule (diatom shell) seems to be

15012-785: The ocean dictates competitive dominance within phytoplankton communities. Each ratio essentially tips the odds in favor of either diatoms or other groups of phytoplankton, such as coccolithophores. A low silicate to nitrogen and phosphorus ratio allows coccolithophores to outcompete other phytoplankton species; however, when silicate to phosphorus to nitrogen ratios are high coccolithophores are outcompeted by diatoms. The increase in agricultural processes lead to eutrophication of waters and thus, coccolithophore blooms in these high nitrogen and phosphorus, low silicate environments. The calcite in calcium carbonate allows coccoliths to scatter more light than they absorb. This has two important consequences: 1) Surface waters become brighter, meaning they have

15151-520: The ocean to survive, so they thrive in areas with large inputs of nutrient rich water upwelling from the lower levels of the ocean. Most coccolithophores require sunlight only for energy production, and have a higher ratio of nitrate uptake over ammonium uptake (nitrogen is required for growth and can be used directly from nitrate but not ammonium). Because of this they thrive in still, nutrient-poor environments where other phytoplankton are starving. Trade-offs associated with these faster growth rates include

15290-504: The ocean. Controversy about manipulating the ecosystem and the efficiency of iron fertilization has slowed such experiments. The ocean science community still has a divided attitude toward the study of iron fertilization as a potential marine Carbon Dioxide Removal (mCDR) approach. 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. The effects of anthropogenic warming on

15429-457: The oceans such as the Southern Ocean , phytoplankton are often limited by the lack of the micronutrient iron . This has led to some scientists advocating iron fertilization as a means to counteract the accumulation of human-produced carbon dioxide (CO 2 ) in the atmosphere . Large-scale experiments have added iron (usually as salts such as ferrous sulfate ) to the oceans to promote phytoplankton growth and draw atmospheric CO 2 into

15568-445: The only known organisms capable of producing methane. Under stressful environmental conditions that cause DNA damage , some species of archaea aggregate and transfer DNA between cells. The function of this transfer appears to be to replace damaged DNA sequence information in the recipient cell by undamaged sequence information from the donor cell. Eukaryotic cells contain membrane bound organelles. Some examples include mitochondria,

15707-422: The oxygen production despite amounting to only ~1% of global plant biomass. In comparison with terrestrial plants, marine phytoplankton are distributed over a larger surface area, are exposed to less seasonal variation and have markedly faster turnover rates than trees (days versus decades). Therefore, phytoplankton respond rapidly on a global scale to climate variations. These characteristics are important when one

15846-434: The past century, but these conclusions have been questioned because of the limited availability of long-term phytoplankton data, methodological differences in data generation and the large annual and decadal variability in phytoplankton production. Moreover, other studies suggest a global increase in oceanic phytoplankton production and changes in specific regions or specific phytoplankton groups. The global Sea Ice Index

15985-487: The poles. Phytoplankton release dissolved organic carbon (DOC) into the ocean. Since phytoplankton are the basis of marine food webs , they serve as prey for zooplankton , fish larvae and other heterotrophic organisms. They can also be degraded by bacteria or by viral lysis . Although some phytoplankton cells, such as dinoflagellates , are able to migrate vertically, they are still incapable of actively moving against currents, so they slowly sink and ultimately fertilize

16124-839: The population of cloud condensation nuclei , mostly leading to increased cloud cover and cloud albedo according to the so-called CLAW hypothesis . Different types of phytoplankton support different trophic levels within varying ecosystems. In oligotrophic oceanic regions such as the Sargasso Sea or the South Pacific Gyre , phytoplankton is dominated by the small sized cells, called picoplankton and nanoplankton (also referred to as picoflagellates and nanoflagellates), mostly composed of cyanobacteria ( Prochlorococcus , Synechococcus ) and picoeucaryotes such as Micromonas . Within more productive ecosystems, dominated by upwelling or high terrestrial inputs, larger dinoflagellates are

16263-714: The possible presence of a sexual reproduction process due to the diploid stages of the coccolithophores, but this process has never been observed. K or r- selected strategies of coccolithophores depend on their life cycle stage. When coccolithophores are diploid, they are r-selected. In this phase they tolerate a wider range of nutrient compositions. When they are haploid they are K- selected and are often more competitive in stable low nutrient environments. Most coccolithophores are K strategist and are usually found on nutrient-poor surface waters. They are poor competitors when compared to other phytoplankton and thrive in habitats where other phytoplankton would not survive. These two stages in

16402-456: The precursors to today's unicellular organisms. Although the origin of life is largely still a mystery, in the currently prevailing theory, known as the RNA world hypothesis , early RNA molecules would have been the basis for catalyzing organic chemical reactions and self-replication. Compartmentalization was necessary for chemical reactions to be more likely as well as to differentiate reactions with

16541-409: The primary production in the ocean and microzooplankton can exert a strong grazing pressure on coccolithophore populations. Although calcification does not prevent predation, it has been argued that the coccosphere reduces the grazing efficiency by making it more difficult for the predator to utilise the organic content of coccolithophores. Heterotrophic protists are able to selectively choose prey on

16680-594: The production of calcium carbonate drives surface alkalinity down, and in conditions of low alkalinity the CO 2 is instead released back into the atmosphere. As a result of this, researchers have postulated that large blooms of coccolithophores may contribute to global warming in the short term. A more widely accepted idea, however, is that over the long term coccolithophores contribute to an overall decrease in atmospheric CO 2 concentrations. During calcification two carbon atoms are taken up and one of them becomes trapped as calcium carbonate. This calcium carbonate sinks to

16819-470: The region being known for its diatom predominance. The overlap of two major phytoplankton groups, coccolithophores and diatoms, in the dynamic frontal systems characteristic of this region provides an ideal setting to study environmental influences on the distribution of different species within these taxonomic groups. The Great Calcite Belt, defined as an elevated particulate inorganic carbon (PIC) feature occurring alongside seasonally elevated chlorophyll

16958-437: The reverse of one another, and the advent of respiration coupled with photosynthesis enabled much greater access to energy than fermentation alone. Protozoa are largely defined by their method of locomotion, including flagella , cilia , and pseudopodia . While there has been considerable debate on the classification of protozoa caused by their sheer diversity, in one system there are currently seven phyla recognized under

17097-473: The ribosomal RNA, it was found that the Archaea most likely split from bacteria and were the precursors to modern eukaryotes, and are actually more phylogenetically related to eukaryotes. As their name suggests, Archaea comes from a Greek word archaios, meaning original, ancient, or primitive. Some archaea inhabit the most biologically inhospitable environments on earth, and this is believed to in some ways mimic

17236-570: The role of phytoplankton aerosol emissions on Earth's energy budget. NAAMES was designed to target specific phases of the annual phytoplankton cycle: minimum, climax and the intermediary decreasing and increasing biomass, in order to resolve debates on the timing of bloom formations and the patterns driving annual bloom re-creation. The NAAMES project also investigated the quantity, size, and composition of aerosols generated by primary production in order to understand how phytoplankton bloom cycles affect cloud formations and climate. Phytoplankton are

17375-488: The seafloor with dead cells and detritus . Phytoplankton are crucially dependent on a number of nutrients . These are primarily 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 stoichiometric nutrient composition of phytoplankton drives — and

17514-443: The species Umbellosphaera irregularis , Umbellosphaera tenuis and different species of Gephyrocapsa . Deep-dwelling coccolithophore species abundance is greatly affected by nutricline and thermocline depths. These coccolithophores increase in abundance when the nutricline and thermocline are deep and decrease when they are shallow. The complete distribution of coccolithophores is currently not known and some regions, such as

17653-432: The structure of the phytoplankton, such as a significant reduction in biomass and phytoplankton density, particularly during El Nino phases can occur. The sensitivity of phytoplankton to environmental changes is why they are often used as indicators of estuarine and coastal ecological condition and health. To study these events satellite ocean color observations are used to observe these changes. Satellite images help to have

17792-406: The sun, so they live in the well-lit surface layers ( euphotic zone ) of oceans and lakes. In comparison with terrestrial plants, phytoplankton are distributed over a larger surface area, are exposed to less seasonal variation and have markedly faster turnover rates than trees (days versus decades). As a result, phytoplankton respond rapidly on a global scale to climate variations. Phytoplankton form

17931-472: The sun, the temperature also rises. This, therefore, maintains the balance and equilibrium of nature. Single-celled organisms Although some prokaryotes live in colonies , they are not specialised cells with differing functions. These organisms live together, and each cell must carry out all life processes to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other to survive. Most multicellular organisms have

18070-423: The total alkalinity of seawater and releases CO 2 . Thus, coccolithophores play an important role in the marine carbon cycle by influencing the efficiency of the biological carbon pump and the oceanic uptake of atmospheric CO 2 . As of 2021, it is not known why coccolithophores calcify and how their ability to produce coccoliths is associated with their ecological success. The most plausible benefit of having

18209-501: The upper sunlit layer of marine and fresh water bodies of water on Earth. Paralleling plants on land, phytoplankton undertake primary production in water, creating organic compounds from carbon dioxide dissolved in the water. Phytoplankton form the base of — and sustain — the aquatic food web , and are crucial players in the Earth's carbon cycle . Phytoplankton are very diverse, comprising photosynthesizing bacteria ( cyanobacteria ) and various unicellular protist groups (notably

18348-446: The various environmental factors that together affect phytoplankton productivity . All of these factors are expected to undergo significant changes in the future ocean due to global change. Global warming simulations predict oceanic temperature increase; dramatic changes in oceanic stratification , circulation and changes in cloud cover and sea ice, resulting in an increased light supply to the ocean surface. Also, reduced nutrient supply

18487-411: The virus, the co-evolutionary " arms race " between coccolithophores and these viruses does not follow the classic Red Queen evolutionary framework, but instead a "Cheshire Cat" ecological dynamic. More recent work has suggested that viral synthesis of sphingolipids and induction of programmed cell death provides a more direct link to study a Red Queen-like coevolutionary arms race at least between

18626-402: The water more acidic. The combination of photosynthesis and calcification therefore even out each other regarding pH changes. In addition, these exoskeletons may confer an advantage in energy production, as coccolithogenesis seems highly coupled with photosynthesis. Organic precipitation of calcium carbonate from bicarbonate solution produces free carbon dioxide directly within the cellular body of

18765-471: The wavelength of light different efficiently and the light is not a single ecological resource but a multitude of resources depending on its spectral composition. By that it was found that changes in the spectrum of light alone can alter natural phytoplankton communities even if the same intensity is available. For growth, phytoplankton cells additionally depend on nutrients, which enter the ocean by rivers, continental weathering, and glacial ice meltwater on

18904-402: The world ocean using ocean-colour data from satellites, and found the calorific value of phytoplankton to vary considerably across different oceanic regions and between different time of the year. The production of phytoplankton under artificial conditions is itself a form of aquaculture. Phytoplankton is cultured for a variety of purposes, including foodstock for other aquacultured organisms,

19043-479: The world's oldest forms of life, and are found virtually everywhere in nature. Many common bacteria have plasmids , which are short, circular, self-replicating DNA molecules that are separate from the bacterial chromosome. Plasmids can carry genes responsible for novel abilities, of current critical importance being antibiotic resistance. Bacteria predominantly reproduce asexually through a process called binary fission . However, about 80 different species can undergo

19182-623: Was a sharp drop during the Cretaceous-Paleogene extinction event , when more than 90% of coccolithophore species became extinct. Coccoliths reached another, lower apex of diversity during the Paleocene-Eocene thermal maximum , but have subsequently declined since the Oligocene due to decreasing global temperatures, with species that produced large and heavily calcified coccoliths most heavily affected. Each coccolithophore encloses itself in

19321-405: Was hypothesised to be due to size selective feeding behaviour, since calcified cells are larger than non-calcified E. huxleyi . In 2015, Harvey et al. investigated predation by the dinoflagellate O. marina on different genotypes of non-calcifying E. huxleyi as well as calcified strains that differed in the degree of calcification. They found that the ingestion rate of O. marina was dependent on

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