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117-554: Naute Dam supplies potable water to Keetmanshoop and some surrounding farms, but is predominantly used for irrigation. It has been consistently underutilised and is one of just a few dams in Namibia that are often filled to capacity. The Naute Aqua Fish Farms Project , a government-owned fish farm , is based at the dam. Naute Fruit Farm is also located at the Naute Dam. The farm primarily grows dates for export to Europe. In 2009,

234-537: A 2-acre (8,100 m ) area. ). However, fish tend also to be animals that aggregate into large schools at high density. Most successful aquaculture species are schooling species, which do not have social problems at high density. Aquaculturists feel that operating a rearing system above its design capacity or above the social density limit of the fish will result in decreased growth rate and increased feed conversion ratio (kg dry feed/kg of fish produced), which results in increased cost and risk of health problems along with

351-503: A biochemical pump that collects carbon from the organ interior (or from the soil ) and not from the atmosphere. Cyanobacteria possess carboxysomes , which increase the concentration of CO 2 around RuBisCO to increase the rate of photosynthesis. An enzyme, carbonic anhydrase , located within the carboxysome, releases CO 2 from dissolved hydrocarbonate ions (HCO 3 ). Before the CO 2 can diffuse out, RuBisCO concentrated within

468-402: A clinical nutrition approach using functional feeds could potentially move away from chemotherapeutic and antibiotic treatments, which could lower the costs of disease treatment and management in fish farms. In this investigation three fishmeal-based diets were served—one made of 31% lipid and the other two made of 18% lipid (one contained fishmeal and the other krill meal. Results demonstrated

585-496: A controversial one. Many cultured fishes (tilapia, carp, catfish, many others) can be raised on a strictly herbivorous diet. Top-level carnivores (most salmonidae species in particular) on the other hand, depend on fish feed, of which a large portion is usually derived from wild-caught fish ( anchovies , menhaden , etc.). Vegetable-derived proteins have successfully replaced fish meal in feeds for carnivorous fishes, but vegetable-derived oils have not successfully been incorporated into

702-588: A dam, floodgate or canal in Africa is a stub . You can help Misplaced Pages by expanding it . Fish farming Fish farming or pisciculture involves commercial breeding of fish , most often for food , in fish tanks or artificial enclosures such as fish ponds . It is a particular type of aquaculture , which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans , molluscs and so on, in natural or pseudo-natural environments. A facility that releases juvenile fish into

819-481: A decrease in profits. Stressing the animals is not desirable, but the concept of and measurement of stress must be viewed from the perspective of the animal using the scientific method. Sea lice , particularly Lepeophtheirus salmonis and various Caligus species, including C. clemensi and C. rogercresseyi , can cause deadly infestations of both farm-grown and wild salmon. Sea lice are ectoparasites which feed on mucus, blood, and skin, and migrate and latch onto

936-409: A different leaf anatomy from C 3 plants, and fix the CO 2 at night, when their stomata are open. CAM plants store the CO 2 mostly in the form of malic acid via carboxylation of phosphoenolpyruvate to oxaloacetate , which is then reduced to malate. Decarboxylation of malate during the day releases CO 2 inside the leaves, thus allowing carbon fixation to 3-phosphoglycerate by RuBisCO. CAM

1053-554: A food containing dried Schizochytrium in place of fish oil . When compared to a control group raised on regular food, they exhibited higher weight gain and better food-to-growth conversion, plus their flesh was higher in healthy omega-3 fatty acids . Within intensive and extensive aquaculture methods, numerous specific types of fish farms are used; each has benefits and applications unique to its design. Fish cages are placed in lakes, bayous, ponds, rivers, or oceans to contain and protect fish until they can be harvested. The method

1170-421: A greenhouse. A hydroponic bed is placed near, above or between them. When tilapia are raised in the tanks, they are able to eat algae, which naturally grow in the tanks when the tanks are properly fertilized. The tank water is slowly circulated to the hydroponic beds, where the tilapia waste feeds commercial plant crops. Carefully cultured microorganisms in the hydroponic bed convert ammonia to nitrates , and

1287-480: A phospholipid outer membrane, and an intermembrane space. Enclosed by the membrane is an aqueous fluid called the stroma. Embedded within the stroma are stacks of thylakoids (grana), which are the site of photosynthesis. The thylakoids appear as flattened disks. The thylakoid itself is enclosed by the thylakoid membrane, and within the enclosed volume is a lumen or thylakoid space. Embedded in the thylakoid membrane are integral and peripheral membrane protein complexes of

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1404-479: A photocomplex. When a photon is absorbed by a chromophore, it is converted into a quasiparticle referred to as an exciton , which jumps from chromophore to chromophore towards the reaction center of the photocomplex, a collection of molecules that traps its energy in a chemical form accessible to the cell's metabolism. The exciton's wave properties enable it to cover a wider area and try out several possible paths simultaneously, allowing it to instantaneously "choose"

1521-405: A photon by the antenna complex loosens an electron by a process called photoinduced charge separation . The antenna system is at the core of the chlorophyll molecule of the photosystem II reaction center. That loosened electron is taken up by the primary electron-acceptor molecule, pheophytin . As the electrons are shuttled through an electron transport chain (the so-called Z-scheme shown in

1638-422: A plant's photosynthetic response. Integrated chlorophyll fluorometer – gas exchange systems allow a more precise measure of photosynthetic response and mechanisms. While standard gas exchange photosynthesis systems can measure Ci, or substomatal CO 2 levels, the addition of integrated chlorophyll fluorescence measurements allows a more precise measurement of C C, the estimation of CO 2 concentration at

1755-648: A prominent part in keeping the tilapia healthy with recirculated water. A number of large, well-capitalized ventures in this area have failed. Managing both the biology and markets is complicated. One future development is the combination of integrated recycling systems with urban farming as tried in Sweden by the Greenfish Initiative . This is also called a "flow through system" . Trout and other sport fish are often raised from eggs to fry or fingerlings and then trucked to streams and released. Normally,

1872-526: A record 82.1 million tonnes in 2018. Farming carnivorous fish such as salmon , however, does not always reduce pressure on wild fisheries, such farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish . The 2008 global returns for fish farming recorded by the FAO totaled 33.8 million tonnes worth about US$ 60 billion. Although fish farming for food is the most widespread, another major fish farming industry provides living fish for

1989-450: A redox-active tyrosine residue that is oxidized by the energy of P680 . This resets the ability of P680 to absorb another photon and release another photo-dissociated electron. The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions and a calcium ion ; this oxygen-evolving complex binds two water molecules and contains the four oxidizing equivalents that are used to drive

2106-466: A result, the food available in all the parts of the pond is used. Fish used in this system include catla and silver carp (surface feeders), rohu (a column feeder), and mrigal and common carp (bottom feeders). Other fish also feed on the excreta of the common carp, and this helps contribute to the efficiency of the system which in optimal conditions produces 3000–6000 kg of fish per hectare per year. One problem with such composite fish culture

2223-423: A series of mesh-wire frames and nets. It is designed to disperse wastes better than more conventional farms in sheltered coastal waters, therefore supporting higher fish packing density. Recently, copper alloys have become important netting materials in aquaculture . Copper alloys are antimicrobial , that is, they destroy bacteria , viruses , fungi , algae , and other microbes . In the marine environment ,

2340-427: A significant difference in the immune and inflammatory responses and pathology in heart tissue as the fish were infected with PMCV. Fish fed with functional feeds with low lipid content demonstrated milder and delayed inflammatory response and therefore, less severe heart lesions at earlier and later stages after PMCV infection. Secondly, farmed fish are kept in concentrations never seen in the wild (e.g. 50,000 fish in

2457-399: A simpler method that employs a pigment similar to those used for vision in animals. The bacteriorhodopsin changes its configuration in response to sunlight, acting as a proton pump. This produces a proton gradient more directly, which is then converted to chemical energy. The process does not involve carbon dioxide fixation and does not release oxygen, and seems to have evolved separately from

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2574-481: A source of carbon atoms to carry out photosynthesis; photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon. In plants, algae, and cyanobacteria, photosynthesis releases oxygen. This oxygenic photosynthesis is by far the most common type of photosynthesis used by living organisms. Some shade-loving plants (sciophytes) produce such low levels of oxygen during photosynthesis that they use all of it themselves instead of releasing it to

2691-596: A study in which cardiomyopathy syndrome (CMS), a severe cardiac disease in Atlantic salmon ( Salmo salar ), was investigated pertaining the effects of functional feeds with reduced lipid content and increased eicosapentaenoic acid levels in controlling CMS in salmon after infection with Piscine Myocarditis Virus (PMCV). Functional feeds are defined as high-quality feeds that beyond purposes of nutrition, they are formulated with health promoting features that could be beneficial in supporting disease resistance, such as CMS. Choosing

2808-541: A subsequent sequence of light-independent reactions called the Calvin cycle . In this process, atmospheric carbon dioxide is incorporated into already existing organic compounds, such as ribulose bisphosphate (RuBP). Using the ATP and NADPH produced by the light-dependent reactions, the resulting compounds are then reduced and removed to form further carbohydrates, such as glucose . In other bacteria, different mechanisms like

2925-405: A type of non- carbon-fixing anoxygenic photosynthesis, where the simpler photopigment retinal and its microbial rhodopsin derivatives are used to absorb green light and power proton pumps to directly synthesize adenosine triphosphate (ATP), the "energy currency" of cells. Such archaeal photosynthesis might have been the earliest form of photosynthesis that evolved on Earth, as far back as

3042-472: A weak condition or if the chemical concentration is too strong. A 2008 meta-analysis of available data shows that salmon farming reduces the survival of associated wild salmon populations. This relationship has been shown to hold for Atlantic, steelhead, pink, chum, and coho salmon. The decrease in survival or abundance often exceeds 50%. Photosynthetic Photosynthesis ( / ˌ f oʊ t ə ˈ s ɪ n θ ə s ɪ s / FOH -tə- SINTH -ə-sis )

3159-591: A wide variety of colors. These pigments are embedded in plants and algae in complexes called antenna proteins. In such proteins, the pigments are arranged to work together. Such a combination of proteins is also called a light-harvesting complex . Although all cells in the green parts of a plant have chloroplasts, the majority of those are found in specially adapted structures called leaves . Certain species adapted to conditions of strong sunlight and aridity , such as many Euphorbia and cactus species, have their main photosynthetic organs in their stems. The cells in

3276-590: Is a system of biological processes by which photosynthetic organisms , such as most plants, algae , and cyanobacteria , convert light energy , typically from sunlight, into the chemical energy necessary to fuel their metabolism . Photosynthesis usually refers to oxygenic photosynthesis , a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen , cellulose and starches . To use this stored chemical energy, an organism's cells metabolize

3393-650: Is achieved by bubbling, cascade flow, or aqueous oxygen. Catfish in genus Clarias can breathe atmospheric air and can tolerate much higher levels of pollutants than trout or salmon, which makes aeration and water purification less necessary and makes Clarias species especially suited for intensive fish production. In some Clarias farms, about 10% of the water volume can consist of fish biomass . The risk of infections by parasites such as fish lice, fungi ( Saprolegnia spp.), intestinal worms (such as nematodes or trematodes ), bacteria (e.g., Yersinia spp., Pseudomonas spp.), and protozoa (such as dinoflagellates )

3510-492: Is also called "off-shore cultivation" when the cages are placed in the sea. They can be constructed of a wide variety of components. Fish are stocked in cages, artificially fed, and harvested when they reach market size. A few advantages of fish farming with cages are that many types of waters can be used (rivers, lakes, filled quarries, etc.), many types of fish can be raised, and fish farming can co-exist with sport fishing and other water uses. Cage farming of fishes in open seas

3627-653: Is also gaining in popularity. Given concerns of disease, poaching, poor water quality, etc., generally pond systems are considered simpler to start and easier to manage. Also, the past occurrences of cage-failures leading to escapes, have raised concern regarding the culture of non-native fish species in dam or open-water cages. On August 22, 2017, there was a massive failure of such cages at a commercial fishery in Washington state in Puget Sound , leading to release of nearly 300,000 Atlantic salmon in non-native waters. This

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3744-490: Is an endothermic redox reaction. In general outline, photosynthesis is the opposite of cellular respiration : while photosynthesis is a process of reduction of carbon dioxide to carbohydrates, cellular respiration is the oxidation of carbohydrates or other nutrients to carbon dioxide. Nutrients used in cellular respiration include carbohydrates, amino acids and fatty acids. These nutrients are oxidized to produce carbon dioxide and water, and to release chemical energy to drive

3861-478: Is believed to risk endangering the native Pacific salmon species. Marine Scotland has kept records of caged fish escapes since 1999. They have recorded 357 fish escape incidents with 3,795,206 fish escaping into fresh and salt water. One company, Dawnfresh Farming Limited has been responsible for 40 incident and 152,790 Rainbow Trout escaping into freshwater lochs. Though the cage-industry has made numerous technological advances in cage construction in recent years,

3978-502: Is both an evolutionary precursor to C 4 and a useful carbon-concentrating mechanism in its own right. Xerophytes , such as cacti and most succulents , also use PEP carboxylase to capture carbon dioxide in a process called Crassulacean acid metabolism (CAM). In contrast to C 4 metabolism, which spatially separates the CO 2 fixation to PEP from the Calvin cycle, CAM temporally separates these two processes. CAM plants have

4095-474: Is commonly measured in μmols /( m / s ), parts per million, or volume per million; and H 2 O is commonly measured in mmols /(m /s) or in mbars . By measuring CO 2 assimilation , ΔH 2 O, leaf temperature, barometric pressure , leaf area, and photosynthetically active radiation (PAR), it becomes possible to estimate, "A" or carbon assimilation, "E" or transpiration , "gs" or stomatal conductance , and "Ci" or intracellular CO 2 . However, it

4212-430: Is converted to CO 2 by an oxalate oxidase enzyme, and the produced CO 2 can support the Calvin cycle reactions. Reactive hydrogen peroxide (H 2 O 2 ), the byproduct of oxalate oxidase reaction, can be neutralized by catalase . Alarm photosynthesis represents a photosynthetic variant to be added to the well-known C4 and CAM pathways. However, alarm photosynthesis, in contrast to these pathways, operates as

4329-420: Is economical only for high-value products, such as broodstock for egg production, fingerlings for net pen aquaculture operations, sturgeon production, research animals, and some special niche markets such as live fish. Raising ornamental coldwater fish ( goldfish or koi ), although theoretically much more profitable due to the higher income per weight of fish produced, has been successfully carried out only in

4446-541: Is estimated to produce as much organic waste as equivalent to a town of people between 10,000 and 20,000 people each year. Today 50% of the world's seafood is farm-raised. These use irrigation ditches or farm ponds to raise fish. The basic requirement is to have a ditch or pond that retains water, possibly with an above-ground irrigation system (many irrigation systems use buried pipes with headers). Using this method, water allotments can be stored in ponds or ditches, usually lined with bentonite clay. In small systems,

4563-419: Is freed from its locked position through a classic "hop". The movement of the electron towards the photo center is therefore covered in a series of conventional hops and quantum walks. Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3.4 billion years old. More recent studies also suggest that photosynthesis may have begun about 3.4 billion years ago, though

4680-412: Is further excited by the light absorbed by that photosystem . The electron is then passed along a chain of electron acceptors to which it transfers some of its energy . The energy delivered to the electron acceptors is used to move hydrogen ions across the thylakoid membrane into the lumen . The electron is eventually used to reduce the coenzyme NADP with an H to NADPH (which has functions in

4797-513: Is higher than in extensive farming, especially because of the high cost of fish feed . It must contain a much higher level of protein (up to 60%) than cattle feed and a balanced amino acid composition, as well. These higher protein-level requirements are a consequence of the higher feed efficiency of aquatic animals (higher feed conversion ratio [FCR], that is, kg of feed per kg of animal produced). Fish such as salmon have an FCR around 1.1 kg of feed per kg of salmon whereas chickens are in

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4914-451: Is more common to use chlorophyll fluorescence for plant stress measurement , where appropriate, because the most commonly used parameters FV/FM and Y(II) or F/FM' can be measured in a few seconds, allowing the investigation of larger plant populations. Gas exchange systems that offer control of CO 2 levels, above and below ambient , allow the common practice of measurement of A/Ci curves, at different CO 2 levels, to characterize

5031-406: Is passed through a food chain . The fixation or reduction of carbon dioxide is a process in which carbon dioxide combines with a five-carbon sugar , ribulose 1,5-bisphosphate , to yield two molecules of a three-carbon compound, glycerate 3-phosphate , also known as 3-phosphoglycerate. Glycerate 3-phosphate, in the presence of ATP and NADPH produced during the light-dependent stages,

5148-601: Is prevented and oxygen levels stay high. Yields can be low if the fish grow ill from electrolyte stress. The composite fish culture system is a technology developed in India by the Indian Council of Agricultural Research in the 1970s. In this system, of both local and imported fish, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them by having different types of food habitats. As

5265-623: Is reduced to glyceraldehyde 3-phosphate . This product is also referred to as 3-phosphoglyceraldehyde (PGAL) or, more generically, as triose phosphate. Most (five out of six molecules) of the glyceraldehyde 3-phosphate produced are used to regenerate ribulose 1,5-bisphosphate so the process can continue. The triose phosphates not thus "recycled" often condense to form hexose phosphates, which ultimately yield sucrose , starch , and cellulose , as well as glucose and fructose . The sugars produced during carbon metabolism yield carbon skeletons that can be used for other metabolic reactions like

5382-401: Is similar to that in animal husbandry , especially at high population densities. However, animal husbandry is a larger and more technologically mature area of human agriculture and has developed better solutions to pathogen problems. Intensive aquaculture has to provide adequate water quality (oxygen, ammonia, nitrite, etc.) levels to minimize stress on the fish. This requirement makes control of

5499-424: Is that many of these fish breed only during monsoon. Even if fish are collected from the wild, they can be mixed with other species, as well. Thus, a major problem in fish farming is the lack of availability of good-quality stock. To overcome this problem, ways have now been worked out to breed these fish in ponds using hormonal stimulation. This has ensured the supply of pure fish stock in desired quantities. One of

5616-421: Is the other form of fish farming. Extensive aquaculture is more basic than intensive aquaculture in that less effort is put into the husbandry of the fish. Extensive aquaculture is done in the ocean, natural and man-made lakes, bays, rivers, and Fiords. Fish are contained within these habitats by multiple mesh enclosures which also function as trapping nets during harvest (Figure 3) (4). Since fish are susceptible to

5733-429: Is then translocated to specialized bundle sheath cells where the enzyme RuBisCO and other Calvin cycle enzymes are located, and where CO 2 released by decarboxylation of the four-carbon acids is then fixed by RuBisCO activity to the three-carbon 3-phosphoglyceric acids . The physical separation of RuBisCO from the oxygen-generating light reactions reduces photorespiration and increases CO 2 fixation and, thus,

5850-404: Is then converted into the final carbohydrate products. The simple carbon sugars photosynthesis produces are then used to form other organic compounds , such as the building material cellulose , the precursors for lipid and amino acid biosynthesis, or as a fuel in cellular respiration . The latter occurs not only in plants but also in animals when the carbon and energy from plants

5967-499: Is used by 16,000 species of plants. Calcium-oxalate -accumulating plants, such as Amaranthus hybridus and Colobanthus quitensis , show a variation of photosynthesis where calcium oxalate crystals function as dynamic carbon pools , supplying carbon dioxide (CO 2 ) to photosynthetic cells when stomata are partially or totally closed. This process was named alarm photosynthesis . Under stress conditions (e.g., water deficit ), oxalate released from calcium oxalate crystals

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6084-474: Is vital for climate processes, as it captures carbon dioxide from the air and binds it into plants, harvested produce and soil. Cereals alone are estimated to bind 3,825 Tg or 3.825 Pg of carbon dioxide every year, i.e. 3.825 billion metric tons. Most photosynthetic organisms are photoautotrophs , which means that they are able to synthesize food directly from carbon dioxide and water using energy from light. However, not all organisms use carbon dioxide as

6201-494: The Pacific coast of Canada , the louse-induced mortality of pink salmon in some regions is commonly over 80%. In Scotland, official figures show that more than nine million fish were lost to disease, parasites, botched treatment attempts and other problems on fish farms between 2016 and 2019. One of the treatments for parasite infestations involved bathing fish in hydrogen peroxide, which can harm or kill farmed fish if they are in

6318-578: The Paleoarchean , preceding that of cyanobacteria (see Purple Earth hypothesis ). While the details may differ between species , the process always begins when light energy is absorbed by the reaction centers , proteins that contain photosynthetic pigments or chromophores . In plants, these proteins are chlorophylls (a porphyrin derivative that absorbs the red and blue spectrums of light, thus reflecting green) held inside chloroplasts , abundant in leaf cells. In bacteria, they are embedded in

6435-546: The Sargasso Sea breeding grounds, for their farms. The European eel is threatened with extinction because of the excessive catch of glass eels by Spanish fishermen and overfishing of adult eels in, e.g., the Dutch IJsselmeer . Although European eel larvae can survive for several weeks, the full life cycle has not yet been achieved in captivity. There is a growing consensus that fish can feel pain . Despite

6552-628: The aquarium trade. The vast majority of freshwater fish in the aquarium trade originate from farms in Eastern and Southern Asia, eastern Europe, Florida and South America that use either indoor tank systems or outdoor pond systems, while farming of fish for the marine aquarium trade happens at a much smaller scale. In 2022 24% of fishers and fish farmers and 62% of workers in post-harvest sector were women. Aquaculture makes use of local photosynthetic production (extensive) or fish that are fed with external food supply (intensive). Extensive aquaculture

6669-637: The light reaction of photosynthesis by using chlorophyll fluorometers . Actual plants' photosynthetic efficiency varies with the frequency of the light being converted, light intensity , temperature , and proportion of carbon dioxide in the atmosphere , and can vary from 0.1% to 8%. By comparison, solar panels convert light into electric energy at an efficiency of approximately 6–20% for mass-produced panels, and above 40% in laboratory devices. Scientists are studying photosynthesis in hopes of developing plants with increased yield . The efficiency of both light and dark reactions can be measured, but

6786-434: The light-independent (or "dark") reactions, the enzyme RuBisCO captures CO 2 from the atmosphere and, in a process called the Calvin cycle , uses the newly formed NADPH and releases three-carbon sugars , which are later combined to form sucrose and starch . The overall equation for the light-independent reactions in green plants is Carbon fixation produces the three-carbon sugar intermediate , which

6903-417: The palisade mesophyll cells where most of the photosynthesis takes place. In the light-dependent reactions , one molecule of the pigment chlorophyll absorbs one photon and loses one electron . This electron is taken up by a modified form of chlorophyll called pheophytin , which passes the electron to a quinone molecule, starting the flow of electrons down an electron transport chain that leads to

7020-417: The photosynthetic capacity of the leaf . C 4 plants can produce more sugar than C 3 plants in conditions of high light and temperature . Many important crop plants are C 4 plants, including maize , sorghum , sugarcane , and millet . Plants that do not use PEP-carboxylase in carbon fixation are called C 3 plants because the primary carboxylation reaction , catalyzed by RuBisCO, produces

7137-462: The photosystems , quantum efficiency and the CO 2 assimilation rates. With some instruments, even wavelength dependency of the photosynthetic efficiency can be analyzed . A phenomenon known as quantum walk increases the efficiency of the energy transport of light significantly. In the photosynthetic cell of an alga , bacterium , or plant, there are light-sensitive molecules called chromophores arranged in an antenna-shaped structure called

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7254-437: The plasma membrane . In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting of water is used in the creation of two important molecules that participate in energetic processes: reduced nicotinamide adenine dinucleotide phosphate (NADPH) and ATP. In plants, algae, and cyanobacteria, sugars are synthesized by

7371-454: The reverse Krebs cycle are used to achieve the same end. The first photosynthetic organisms probably evolved early in the evolutionary history of life using reducing agents such as hydrogen or hydrogen sulfide, rather than water, as sources of electrons. Cyanobacteria appeared later; the excess oxygen they produced contributed directly to the oxygenation of the Earth , which rendered

7488-429: The sustainable yields of wild fish populations. While fish farming is practised worldwide, China alone provides 62% of the world's farmed fish production. As of 2016, more than 50% of seafood was produced by aquaculture. In the last three decades, aquaculture has been the main driver of the increase in fisheries and aquaculture production, with an average growth of 5.3 percent per year in the period 2000–2018, reaching

7605-407: The 2.5 kg of feed per kg of chicken range. Fish do not use energy to keep warm, eliminating some carbohydrates and fats in the diet, required to provide this energy. This may be offset, though, by the lower land costs and the higher production which can be obtained due to the high level of input control. Aeration of the water is essential, as fish need a sufficient oxygen level for growth. This

7722-579: The 21st century. The increased incidences of dangerous viral diseases of koi carp, together with the high value of the fish, has led to initiatives in closed-system koi breeding and growing in a number of countries. Today, a few commercially successful intensive koi-growing facilities are operating in the UK, Germany, and Israel. Some producers have adapted their intensive systems in an effort to provide consumers with fish that do not carry dormant forms of viruses and diseases. In 2016, juvenile Nile tilapia were given

7839-433: The CO 2 concentration in the leaves under these conditions. Plants that use the C 4 carbon fixation process chemically fix carbon dioxide in the cells of the mesophyll by adding it to the three-carbon molecule phosphoenolpyruvate (PEP), a reaction catalyzed by an enzyme called PEP carboxylase , creating the four-carbon organic acid oxaloacetic acid . Oxaloacetic acid or malate synthesized by this process

7956-838: The Google headquarters in Mountain View, California, showing off feed made from seaweed extracts, yeast , and algae grown in bioreactors ." Not only do the feeds for carnivorous fish, like certain salmon species, remain controversial due to the containment of wild caught fish like anchovies, but they are not helping the health of the fish, as is the case in Norway. Between 2003 and 2007, Aldrin et al. examined three infectious diseases in Norwegian salmon fish farms—heart and skeletal muscle inflammation, pancreas disease, and infectious salmon anemia. In 2014, Martinez-Rubio et al. conducted

8073-419: The action spectrum is blue-green light, which allows these algae to use the blue end of the spectrum to grow in the deeper waters that filter out the longer wavelengths (red light) used by above-ground green plants. The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e.g., green plants, red algae, purple bacteria ) and is the least effective for photosynthesis in

8190-1022: The antimicrobial/algaecidal properties of copper alloys prevent biofouling , which can briefly be described as the undesirable accumulation, adhesion, and growth of microorganisms, plants, algae , tube worms , barnacles , mollusks , and other organisms. The resistance of organism growth on copper alloy nets also provides a cleaner and healthier environment for farmed fish to grow and thrive. Traditional netting involves regular and labor-intensive cleaning. In addition to its antifouling benefits, copper netting has strong structural and corrosion-resistant properties in marine environments. Copper-zinc brass alloys are deployed in commercial-scale aquaculture operations in Asia, South America, and USA (Hawaii). Extensive research, including demonstrations and trials, are being implemented on two other copper alloys: copper-nickel and copper-silicon. Each of these alloy types has an inherent ability to reduce biofouling, cage waste, disease, and

8307-521: The atmosphere. Although there are some differences between oxygenic photosynthesis in plants , algae , and cyanobacteria , the overall process is quite similar in these organisms. There are also many varieties of anoxygenic photosynthesis , used mostly by bacteria, which consume carbon dioxide but do not release oxygen. Carbon dioxide is converted into sugars in a process called carbon fixation ; photosynthesis captures energy from sunlight to convert carbon dioxide into carbohydrates . Carbon fixation

8424-483: The carboxysome quickly sponges it up. HCO 3 ions are made from CO 2 outside the cell by another carbonic anhydrase and are actively pumped into the cell by a membrane protein. They cannot cross the membrane as they are charged, and within the cytosol they turn back into CO 2 very slowly without the help of carbonic anhydrase. This causes the HCO 3 ions to accumulate within the cell from where they diffuse into

8541-491: The carboxysomes. Pyrenoids in algae and hornworts also act to concentrate CO 2 around RuBisCO. The overall process of photosynthesis takes place in four stages: Plants usually convert light into chemical energy with a photosynthetic efficiency of 3–6%. Absorbed light that is unconverted is dissipated primarily as heat , with a small fraction (1–2%) reemitted as chlorophyll fluorescence at longer (redder) wavelengths . This fact allows measurement of

8658-812: The competition between organisms for limited resources. Also, when foreign fish interbreed with wild species, they upset the genetic variability of the species, making them more prone to disease and infection. The high density of fish in these mesh tanks is very tempting for predators of the sea and air (19). To protect the harvest from predators protective netting is set up at a high cost. Often times predatorial fish and mammals like seals, sharks, and tuna get caught in these barrier nets and die. Some farmers protect their stocks from predatorial birds such as pelicans and albatross by shooting these sometimes endangered creatures. In these kinds of systems fish production per unit of surface can be increased at will, as long as sufficient oxygen , fresh water and food are provided. Because of

8775-409: The conditions of non-cyclic electron flow in green plants is: Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants , the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with absorption peaks in violet-blue and red light. In red algae ,

8892-514: The diagram), a chemiosmotic potential is generated by pumping proton cations ( H ) across the membrane and into the thylakoid space . An ATP synthase enzyme uses that chemiosmotic potential to make ATP during photophosphorylation , whereas NADPH is a product of the terminal redox reaction in the Z-scheme . The electron enters a chlorophyll molecule in Photosystem I . There it

9009-506: The diets of carnivores. Research is underway to try to change this, such that even salmon and other carnivores could be successfully fed with vegetable products. The F3 Challenge (Fish-Free Feed Challenge), as explained by a report from Wired in February 2017, "is a race to sell 100,000 metric tons of fish food, without the fish. Earlier this month, start-ups from places like Pakistan, China, and Belgium joined their American competition at

9126-437: The elements, site placement is essential to ensure the rapid growth of the targeted species. The drawback of these facilities is that they depend on the surrounding area for good water quality in order to reduce mortality and increase the survivorship and growth rate of the fish (19). Fish chosen for extensive aquaculture are very hardy and often do well in high densities. Seaweed, prawns, mussels, carp, tilapia, tuna and salmon are

9243-510: The environment. The flow allows chemicals, parasites, waste and diseases to spread in the enclosed environment, and this is not beneficial for the natural environment. Another negative consequence is the high escape rate of the cultured fish from these open net pens. These escaped fish also pose a high risk to the surrounding ecosystems. The amount of organic waste produced by fish farms is also alarming. A salmon farm in Scotland , for instance,

9360-505: The equation for this process is: This equation emphasizes that water is both a reactant in the light-dependent reaction and a product of the light-independent reaction , but canceling n water molecules from each side gives the net equation: Other processes substitute other compounds (such as arsenite ) for water in the electron-supply role; for example some microbes use sunlight to oxidize arsenite to arsenate : The equation for this reaction is: Photosynthesis occurs in two stages. In

9477-518: The evolution of complex life possible. The average rate of energy captured by global photosynthesis is approximately 130 terawatts , which is about eight times the total power consumption of human civilization . Photosynthetic organisms also convert around 100–115 billion tons (91–104 Pg petagrams , or billions of metric tons), of carbon into biomass per year. Photosynthesis was discovered in 1779 by Jan Ingenhousz . He showed that plants need light, not just air, soil, and water. Photosynthesis

9594-453: The farm was projected to export 180 tonnes of dates, up from 120 the year before. As of March 2009, the farm employed 76 full-time employees and 250 seasonal workers. 26°55′53″S 17°56′18″E  /  26.9312527778°S 17.9383083333°E  / -26.9312527778; 17.9383083333 This article about a Namibian building or structure related topic is a stub . You can help Misplaced Pages by expanding it . This article about

9711-582: The first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the hydrogen carrier NADPH and the energy-storage molecule ATP . During the second stage, the light-independent reactions use these products to capture and reduce carbon dioxide. Most organisms that use oxygenic photosynthesis use visible light for the light-dependent reactions, although at least three use shortwave infrared or, more specifically, far-red radiation. Some organisms employ even more radical variants of photosynthesis. Some archaea use

9828-441: The first step of the Z-scheme , requires an external source of electrons to reduce its oxidized chlorophyll a reaction center. The source of electrons for photosynthesis in green plants and cyanobacteria is water. Two water molecules are oxidized by the energy of four successive charge-separation reactions of photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions. The electrons yielded are transferred to

9945-434: The fish are often fed commercial fish food, and their waste products can help fertilize the fields. In larger ponds, the pond grows water plants and algae as fish food. Some of the most successful ponds grow introduced strains of plants, as well as introduced strains of fish. Control of water quality is crucial. Fertilizing, clarifying, and pH control of the water can increase yields substantially, as long as eutrophication

10062-441: The fish in large cages floating in the water. The fish are living in natural water but are isolated with a net. Because the only barrier separating the fish from the surrounding environment is a net, this allows the water to flow from the ‘natural’ surrounding through the fish farms. The site of the fish farm is crucial for the farm to be a success or not. Before any fish farm is settled, it is highly recommended to be selective with

10179-546: The fry are raised in long, shallow, concrete tanks, fed with fresh stream water. The fry receive commercial fish food in pellets. While not as efficient as the New Alchemists' method, it is also far simpler and has been used for many years to stock streams with sport fish. European eel ( Anguilla anguilla ) aquaculturalists procure a limited supply of glass eels, juvenile stages of the European eel which swim north from

10296-467: The high amount of organic waste produced by the fish which settles below their pens(4). Phytoplankton and algae break down fecal matter and residual fish meal reducing the amount of available oxygen in the water column, which chokes and kills the Benthic organisms. Another serious problem acquainted with extensive aquaculture is the introduction of invasive species into ecosystems (10). Escaped fish increase

10413-399: The interior of a cell, giving the membrane a very large surface area and therefore increasing the amount of light that the bacteria can absorb. In plants and algae, photosynthesis takes place in organelles called chloroplasts . A typical plant cell contains about 10 to 100 chloroplasts. The chloroplast is enclosed by a membrane. This membrane is composed of a phospholipid inner membrane,

10530-433: The interior tissues of a leaf, called the mesophyll , can contain between 450,000 and 800,000 chloroplasts for every square millimeter of leaf. The surface of the leaf is coated with a water-resistant waxy cuticle that protects the leaf from excessive evaporation of water and decreases the absorption of ultraviolet or blue light to minimize heating . The transparent epidermis layer allows light to pass through to

10647-484: The largest problems with freshwater pisciculture is that it can use a million gallons of water per acre (about 1 m of water per m ) each year. Extended water purification systems allow for the reuse ( recycling ) of local water. The largest-scale pure fish farms use a system derived (admittedly much refined) from the New Alchemy Institute in the 1970s. Basically, large plastic fish tanks are placed in

10764-434: The light reaction, and infrared gas analyzers can measure the dark reaction . An integrated chlorophyll fluorometer and gas exchange system can investigate both light and dark reactions when researchers use the two separate systems together. Infrared gas analyzers and some moisture sensors are sensitive enough to measure the photosynthetic assimilation of CO 2 and of Δ H 2 O using reliable methods . CO 2

10881-433: The light-independent reaction); at that point, the path of that electron ends. The cyclic reaction is similar to that of the non-cyclic but differs in that it generates only ATP, and no reduced NADP (NADPH) is created. The cyclic reaction takes place only at photosystem I. Once the electron is displaced from the photosystem, the electron is passed down the electron acceptor molecules and returns to photosystem I, from where it

10998-432: The more common types of photosynthesis. In photosynthetic bacteria, the proteins that gather light for photosynthesis are embedded in cell membranes . In its simplest form, this involves the membrane surrounding the cell itself. However, the membrane may be tightly folded into cylindrical sheets called thylakoids , or bunched up into round vesicles called intracytoplasmic membranes . These structures can fill most of

11115-439: The most efficient route, where it will have the highest probability of arriving at its destination in the minimum possible time. Because that quantum walking takes place at temperatures far higher than quantum phenomena usually occur, it is only possible over very short distances. Obstacles in the form of destructive interference cause the particle to lose its wave properties for an instant before it regains them once again after it

11232-533: The most prominent forms of extensive aqua cultured seafood. Extensive aquaculture facilities have negative impacts on the environment as well. Natural habitats are destroyed in the development of man made ponds used for extensive aquaculture. In the Philippines, shrimp aquaculture is responsible for the destruction of thousands of acres of mangrove fields which serve as nurseries and living habitats for many marine organisms. Benthic habitats are being depleted due to

11349-439: The need for antibiotics, while simultaneously maintaining water circulation and oxygen requirements. Other types of copper alloys are also being considered for research and development in aquaculture operations. In Southeast Asia , the traditional cage farming platform is called kelong . The open net pens system is a method that takes place in natural waters, such as rivers, lakes, near the coast or offshore. The breeders rear

11466-498: The organic compounds through cellular respiration . Photosynthesis plays a critical role in producing and maintaining the oxygen content of the Earth's atmosphere, and it supplies most of the biological energy necessary for complex life on Earth. Some bacteria also perform anoxygenic photosynthesis , which uses bacteriochlorophyll to split hydrogen sulfide as a reductant instead of water, producing sulfur instead of oxygen. Archaea such as Halobacterium also perform

11583-410: The organism's metabolism . Photosynthesis and cellular respiration are distinct processes, as they take place through different sequences of chemical reactions and in different cellular compartments (cellular respiration in mitochondria ). The general equation for photosynthesis as first proposed by Cornelis van Niel is: Since water is used as the electron donor in oxygenic photosynthesis,

11700-481: The pathogen problem more difficult. Intensive aquaculture requires tight monitoring and a high level of expertise of the fish farmer. Very-high-intensity recycle aquaculture systems (RAS, also Recirculating Aquaculture Systems), where all the production parameters are controlled, are being used for high-value species. By recycling water, little is used per unit of production. However, the process has high capital and operating costs. The higher cost structures mean that RAS

11817-556: The photosynthetic system. Plants absorb light primarily using the pigment chlorophyll . The green part of the light spectrum is not absorbed but is reflected, which is the reason that most plants have a green color. Besides chlorophyll, plants also use pigments such as carotenes and xanthophylls . Algae also use chlorophyll, but various other pigments are present, such as phycocyanin , carotenes , and xanthophylls in green algae , phycoerythrin in red algae (rhodophytes) and fucoxanthin in brown algae and diatoms resulting in

11934-508: The plants are fertilized by the nitrates and phosphates .Other wastes are strained out by the hydroponic media, which double as an aerated pebble-bed filter. This system, properly tuned, produces more edible protein per unit area than any other. A wide variety of plants can grow well in the hydroponic beds. Most growers concentrate on herbs (e.g. parsley and basil ), which command premium prices in small quantities all year long. The most common customers are restaurant wholesalers. Since

12051-476: The production of amino acids and lipids . In hot and dry conditions , plants close their stomata to prevent water loss. Under these conditions, CO 2 will decrease and oxygen gas , produced by the light reactions of photosynthesis, will increase, causing an increase of photorespiration by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and decrease in carbon fixation. Some plants have evolved mechanisms to increase

12168-486: The relationship between the two can be complex. For example, the light reaction creates ATP and NADPH energy molecules , which C 3 plants can use for carbon fixation or photorespiration . Electrons may also flow to other electron sinks. For this reason, it is not uncommon for authors to differentiate between work done under non-photorespiratory conditions and under photorespiratory conditions . Chlorophyll fluorescence of photosystem II can measure

12285-451: The requirement of sufficient fresh water, a massive water purification system must be integrated in the fish farm. One way to achieve this is to combine hydroponic horticulture and water treatment , see below. The exception to this rule are cages which are placed in a river or sea, which supplements the fish crop with sufficient oxygenated water. Some environmentalists object to this practice. The cost of inputs per unit of fish weight

12402-462: The respective organisms . In plants , light-dependent reactions occur in the thylakoid membranes of the chloroplasts where they drive the synthesis of ATP and NADPH . The light-dependent reactions are of two forms: cyclic and non-cyclic . In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments (see diagram at right). The absorption of

12519-440: The risk of damage and escape due to storms is always a concern. Semi-submersible marine technology is beginning to impact fish farming. In 2018, 1.5 million salmon are in the middle of a year-long trial at Ocean Farm 1 off the coast of Norway . The semi-submersible US$ 300 million project is the world's first deep-sea aquaculture project, and includes 61-meter (200 ft)-high by 91-meter (300 ft)-diameter pen made from

12636-415: The site location of the farm. The site must be examined on some essential elements. Important conditions on the location are: Despite these important site conditions, the open net pen method was very popular in Norway and China. This is because of the cost friendliness and efficiency of this method. Because of the ocean's water flow and other reasons, open net pen culture is seen as a high-risk method for

12753-479: The site of carboxylation in the chloroplast, to replace Ci. CO 2 concentration in the chloroplast becomes possible to estimate with the measurement of mesophyll conductance or g m using an integrated system. Photosynthesis measurement systems are not designed to directly measure the amount of light the leaf absorbs, but analysis of chlorophyll fluorescence , P700 - and P515-absorbance, and gas exchange measurements reveal detailed information about, e.g.,

12870-547: The skin of wild salmon during free-swimming, planktonic nauplii and copepodid larval stages, which can persist for several days. Large numbers of highly populated, open-net salmon farms can create exceptionally large concentrations of sea lice; when exposed in river estuaries containing large numbers of open-net farms, many young wild salmon are infected, and do not survive as a result. Adult salmon may survive otherwise critical numbers of sea lice, but small, thin-skinned juvenile salmon migrating to sea are highly vulnerable. On

12987-507: The system lives in a greenhouse , it adapts to almost all temperate climates, and may also adapt to tropical climates . The main environmental impact is discharge of water that must be salted to maintain the fishes' electrolyte balance. Current growers use a variety of proprietary tricks to keep fish healthy, reducing their expenses for salt and wastewater discharge permits. Some veterinary authorities speculate that ultraviolet ozone disinfectant systems (widely used for ornamental fish) may play

13104-468: The three-carbon 3-phosphoglyceric acids directly in the Calvin-Benson cycle . Over 90% of plants use C 3 carbon fixation, compared to 3% that use C 4 carbon fixation; however, the evolution of C 4 in over sixty plant lineages makes it a striking example of convergent evolution . C 2 photosynthesis , which involves carbon-concentration by selective breakdown of photorespiratory glycine,

13221-424: The ultimate reduction of NADP to NADPH . In addition, this creates a proton gradient (energy gradient) across the chloroplast membrane , which is used by ATP synthase in the synthesis of ATP . The chlorophyll molecule ultimately regains the electron it lost when a water molecule is split in a process called photolysis , which releases oxygen . The overall equation for the light-dependent reactions under

13338-711: The vast number of fish consumed, fish welfare has historically received little attention. Farmed fish are usually raised in overcrowded environments, making them susceptible to stress, injuries, aggression and diseases. These conditions prevent them from engaging in natural behaviors such as nesting or migration. Overcrowding often leads to poor water quality due to fish waste and antibiotics use. Sea lice infestations are common and can cause painful lesion, but are typically treated with harsh chemicals. Additionally, fish are genetically engineered to grow larger and faster, leading to health problems such as cataracts and abnormal heart shapes. The issue of feeds in fish farming has been

13455-408: The water-oxidizing reaction (Kok's S-state diagrams). The hydrogen ions are released in the thylakoid lumen and therefore contribute to the transmembrane chemiosmotic potential that leads to ATP synthesis . Oxygen is a waste product of light-dependent reactions, but the majority of organisms on Earth use oxygen and its energy for cellular respiration , including photosynthetic organisms . In

13572-764: The wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery . Worldwide, the most important fish species produced in fish farming are carp , catfish , salmon and tilapia . Global demand is increasing for dietary fish protein , which has resulted in widespread overfishing in wild fisheries , resulting in significant decrease in fish stocks and even complete depletion in some regions. Fish farming allows establishment of artificial fish colonies that are provided with sufficient feeding , protection from natural predators and competitive threats , access to veterinarian service, and easier harvesting when needed, while being separate from and thus do not usually impact

13689-462: Was emitted, hence the name cyclic reaction . Linear electron transport through a photosystem will leave the reaction center of that photosystem oxidized . Elevating another electron will first require re-reduction of the reaction center. The excited electrons lost from the reaction center ( P700 ) of photosystem I are replaced by transfer from plastocyanin , whose electrons come from electron transport through photosystem II . Photosystem II, as

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