69-569: N. alkalicus N. hamburgensis N. vulgaris N. winogradskyi Nitrobacter is a genus comprising rod-shaped , gram-negative , and chemoautotrophic bacteria . The name Nitrobacter derives from the Latin neuter gender noun nitrum, nitri , alkalis; the Ancient Greek noun βακτηρία, βακτηρίᾱς , rod. They are non-motile and reproduce via budding or binary fission . Nitrobacter cells are obligate aerobes and have
138-438: A doubling time of about 13 hours. Nitrobacter play an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil and marine systems. Unlike plants , where electron transfer in photosynthesis provides the energy for carbon fixation , Nitrobacter uses energy from the oxidation of nitrite ions, NO 2 , into nitrate ions, NO 3 , to fulfill their energy needs. Nitrobacter fix carbon dioxide via
207-508: 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 )
276-435: 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
345-583: 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
414-525: 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
483-783: 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
552-495: 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
621-417: 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 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
690-565: 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
759-435: 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
SECTION 10
#1732780788400828-491: 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
897-493: 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
966-457: A two-stage mechanism for nitrification , mediated by two distinct genera of bacteria. The first stage proposed was the conversion of ammonia to nitrite, and the second the oxidation of nitrite to nitrate. Winogradsky named the bacteria responsible for the oxidation of nitrite to nitrate Nitrobacter in his subsequent study on microbial nitrification in 1892. Winslow et al . proposed the type species Nitrobacter winogradsky in 1917. The species
1035-405: A wide variety of habitats. Cells in the genus Nitrobacter have an optimum pH for growth between 7.3 and 7.5. According to Grundmann, Nitrobacter seem to grow optimally at 38 °C and at a pH of 7.9, but Holt states that Nitrobacter grow optimally at 28 °C and within a pH range of 5.8 to 8.5, although they have a pH optima between 7.6 and 7.8. The primary ecological role of members of
1104-434: Is cytoplasmic . Nitrobacter cells have been shown to recover following extreme carbon dioxide exposure and are non-motile. 16s rRNA sequence analysis phylogenetically places Nitrobacter within the class of Alphaproteobacteria . Pairwise evolutionary distance measurements within the genus are low compared to those found in other genera, and are less than 1%. Nitrobacter are also closely related to other species within
1173-500: 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
1242-497: 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
1311-889: 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
1380-510: Is evidence that the nitrification phenotype evolved separately from that found in photosynthetic bacteria. All known nitrite-oxidizing prokaryotes are restricted to a handful of phylogenetic groups. This includes the genus Nitrospira within the phylum Nitrospirota , and the genus Nitrolancetus from the phylum Chloroflexota (formerly Chloroflexi). Before 2004, nitrite oxidation was believed to only occur within Pseudomonadota; it
1449-414: Is likely that further scientific inquiry will expand the list of known nitrite-oxidizing species. The low diversity of species oxidizing nitrite oxidation contrasts with other processes associated with the nitrogen cycle in the ocean, such as denitrification and N-fixation , where a diverse range of taxa perform analogous functions. Nitrification is a crucial component of the nitrogen cycle, especially in
SECTION 20
#17327807884001518-425: 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
1587-666: Is on the process of eutrophication . The distribution and differences in nitrification rates across different species of Nitrobacter may be attributed to differences in the plasmids among species, as data presented in Schutt (1990) imply, habitat-specific plasmid DNA was induced by adaptation for some of the lakes that were investigated. A follow-up study performed by Navarro et al . (1995) showed that various Nitrobacter populations carry two large plasmids. In conjunction with Schutts’ (1990) study, Navarro et al. (1995) illustrated genomic features that may play crucial roles in determining
1656-447: 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
1725-539: Is puzzling to researchers. Complete nitrification, the conversion of ammonia to nitrate in a single step known as comammox , has an energy yield (∆G°′) of −349 kJ mol NH 3 , while the energy yields for the ammonia-oxidation and nitrite-oxidation steps of the observed two-step reaction are −275 kJ mol NH 3 , and −74 kJ mol NO 2 , respectively. These values indicate that it would be energetically favourable for an organism to carry out complete nitrification from ammonia to nitrate ( comammox ), rather than conduct only one of
1794-451: 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
1863-568: Is the basis for the vast majority of oceanic and also many freshwater food webs ( chemosynthesis 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
1932-471: 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
2001-472: Is used and after a lag phase, organic matter is oxidized. Chemoorganotroph growth is slow and unbalanced, thus more poly-β-hydroxybutyrate granules are seen that distort the shape and size of the cells. The enzyme responsible for the oxidation of nitrite to nitrate in members of the genus Nitrobacter is nitrite oxidoreductase (NXR), which is encoded by the gene nxrA . NXR is composed of two subunits, and likely forms an αβ-heterodimer. The enzyme exists within
2070-491: The Alphaproteobacteria , including the photosynthetic Rhodopseudomonas palustris , the root-nodulating Bradyrhizobium japonicum and Blastobacter denitrificans , and the human pathogens Afipia felis and Afipia clevelandensis . Bacteria within the genus Nitrobacter are presumed to have arisen on multiple occasions from a photosynthetic ancestor, and for individual nitrifying genera and species there
2139-580: The Calvin cycle for their carbon requirements. Nitrobacter belongs to the Alphaproteobacteria class of the Pseudomonadota . Nitrobacter are gram-negative bacteria and are either rod-shaped, pear-shaped or pleomorphic . They are typically 0.5–0.9 μm in width and 1.0–2.0 μm in length and have an intra-cytomembrane polar cap . Due to the presence of cytochromes c , they are often yellow in cell suspensions. The nitrate oxidizing system on membranes
Nitrobacter - Misplaced Pages Continue
2208-449: 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
2277-590: 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 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
2346-625: 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
2415-473: The cell on specialized membranes in the cytoplasm that can be folded into vesicles or tubes. The α-subunit is thought to be the location of nitrite oxidation, and the β-subunit is an electron channel from the membrane. The direction of the reaction catalyzed by NXR can be reversed depending on oxygen concentrations. The region of the nxrA gene which encodes for the β-subunit of the NXR enzyme is similar in sequence to
2484-421: The distribution and ecological impact of members of the genus Nitrobacter . Nitrifying bacteria in general tend to be less abundant than their heterotrophic counterparts, as the oxidizing reactions they perform have a low energy yield and most of their energy production goes toward carbon-fixation rather than growth and reproduction. In 1890, Ukrainian - Russian microbiologist Sergei Winogradsky isolated
2553-504: The first pure cultures of nitrifying bacteria which are capable of growth in the absence of organic matter and sunlight . The exclusion of organic material by Winogradsky in the preparation of his cultures is recognized as a contributing factor to his success in isolating the microbes (attempts to isolate pure cultures are difficult due to a tendency for heterotrophic organisms to overtake plates with any presence of organic material). In 1891, English chemist Robert Warington proposed
2622-498: 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
2691-416: The functioning of the planktonic food web. Phytoplankton obtain energy through 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 )
2760-500: The genus Nitrobacter is to oxidize nitrite to nitrate, a primary source of inorganic nitrogen for plants. This role is also essential in aquaponics . Since all members in the genus Nitrobacter are obligate aerobes , oxygen along with phosphorus tend to be factors that limit their capability to perform nitrite oxidation. One of the major impacts of nitrifying bacteria such as ammonia-oxidizing Nitrosomonas and nitrite-oxidizing Nitrobacter in both oceanic and terrestrial ecosystems
2829-400: The genus Nitrobacter use nitrite as a source of electrons ( reductant ), nitrite as a source of energy, and CO 2 as a carbon source. Nitrite is not a particularly favourable substrate from which to gain energy. Thermodynamically, nitrite oxidation gives a yield (∆G°′) of only -74 kJ mol NO 2 . As a result, Nitrobacter has developed a highly specialized metabolism to derive energy from
Nitrobacter - Misplaced Pages Continue
2898-513: 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
2967-493: The inorganic dissolved nitrogen pool in the form of ammonia. Microbe-mediated nitrification converts that ammonia into nitrate, which can subsequently be taken up by phytoplankton and recycled. The nitrite oxidation reaction performed by the Nitrobacter is as follows; NO 2 + H 2 O → NO 3 + 2H + 2e 2H + 2e + ½O 2 → H 2 O The Gibbs' Free Energy yield for nitrite oxidation is: ΔG = -74 kJ mol NO 2 In
3036-556: The iron-sulfur centers of bacterial ferredoxins, and to the β-subunit of the enzyme nitrate reductase, found in Escherichia coli . The genus Nitrobacter is widely distributed in both aquatic and terrestrial environments. Nitrifying bacteria have an optimum growth between 77 and 86 °F (25 and 30 °C), and cannot survive past the upper limit of 120 °F (49 °C) or the lower limit of 32 °F (0 °C). This limits their distribution even though they can be found in
3105-436: 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
3174-501: 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
3243-592: 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
3312-498: 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
3381-504: 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
3450-520: 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
3519-579: The oceans, nitrite-oxidizing bacteria such as Nitrobacter are usually found in close proximity to ammonia-oxidizing bacteria. These two reactions together make up the process of nitrification. The nitrite-oxidation reaction generally proceeds more quickly in ocean waters, and therefore is not a rate-limiting step in nitrification. For this reason, it is rare for nitrite to accumulate in ocean waters. The two-step conversion of ammonia to nitrate observed in ammonia-oxidizing bacteria , ammonia-oxidizing archaea and nitrite-oxidizing bacteria (such as Nitrobacter )
SECTION 50
#17327807884003588-410: The oceans. The production of nitrate (NO 3 ) by oxidation of nitrite (NO 2 ) is accomplished by nitrification - the process that produces the inorganic nitrogen that meets much of the demand of marine oxygenic, photosynthetic organisms such as phytoplankton , particularly in areas of upwelling . For this reason, nitrification supplies much of the nitrogen that fuels planktonic primary production in
3657-405: The oxidation of nitrite. Cells in the genus Nitrobacter reproduce by budding or binary fission. Carboxysomes , which aid carbon fixation, are found in lithoautotrophically and mixotrophically grown cells. Additional energy conserving inclusions are PHB granules and polyphosphates . When both nitrite and organic substances are present, cells can exhibit biphasic growth; first the nitrite
3726-422: 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
3795-428: 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 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
3864-434: 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
3933-487: 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
4002-853: 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
4071-570: 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
4140-488: 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
4209-432: 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
SECTION 60
#17327807884004278-449: The two steps. The evolutionary motivation for a decoupled, two-step nitrification reaction is an area of ongoing research. In 2015, it was discovered that the species Nitrospira inopinata possesses all the enzymes required for carrying out complete nitrification in one step, suggesting that this reaction does occur. This discovery raises questions about evolutionary capability of Nitrobacter to conduct only nitrite-oxidation. Members of
4347-446: 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
4416-471: 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 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
4485-616: 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 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
4554-471: 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
4623-402: 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,
4692-500: The world's oceans. Nitrification is estimated to be the source of half of the nitrate consumed by phytoplankton globally. Phytoplankton are major contributors to oceanic production, and are therefore important for the biological pump which exports carbon and other particulate organic matter from the surface waters of the world's oceans. The process of nitrification is crucial for separating recycled production from production leading to export. Biologically metabolized nitrogen returns to
4761-410: Was officially recognized in 1980. Nitrobacter alkalicus Nitrobacter alkalicus is a nitrite -oxidizing bacteria from the genus of Nitrobacter . This Nitrobacteraceae article is a stub . You can help Misplaced Pages by expanding it . Phytoplankton Phytoplankton ( / ˌ f aɪ t oʊ ˈ p l æ ŋ k t ə n / ) are the autotrophic (self-feeding) components of
#399600