Aquaponics
Encyclopedia
Aquaponics is a sustainable food production
system that combines a traditional aquaculture
(raising aquatic animal
s such as fish
, crayfish
or prawn
s in tanks) with hydroponics
(cultivating plants in water) in a symbiotic
environment. In the aquaculture, effluent
s accumulate in the water, increasing toxicity for the fish. This water is led to a hydroponic system where the by-product
s from the aquaculture are filtered out by the plants as vital nutrients, after which the cleansed water is recirculated back to the animals. The term aquaponics is a portmanteau of the terms aquaculture and hydroponic.
Aquaponic systems vary in size from small indoor or outdoor units to large commercial units, using the same technology. The systems usually contain fresh water, but salt water systems are plausible depending on the type of aquatic animal and which plants. Aquaponic science may still be considered to be at an early stage.
s to neutralize acid
s, or for maintaining water oxygenation. Typical components include:
Depending on the sophistication and cost of the aquaponics system, the units for solids removal, biofiltration, and/or the hydroponics subsystem may be combined into one unit or subsystem, which prevents the water from flowing directly from the aquaculture part of the system to the hydroponics part.
conversion of ammonia into nitrates, is one of the most important functions in an aquaponics system as it reduces the toxicity of the water for fish, and allows the resulting nitrate compounds to be removed by the plants for nourishment. Ammonia is steadily released into the water through the excreta
and gill
s of fish as a product of their metabolism, but must be filtered out of the water since higher concentrations of ammonia (commonly between 0.5 and 1 ppm
) can kill fish. Although plants can absorb ammonia from the water to some degree, nitrates are assimilated more easily, thereby efficiently reducing the toxicity of the water for fish. Ammonia can be converted into other nitrogenous compounds through healthy populations of:
In an aquaponics system, the bacteria responsible for this process form a biofilm
on all solid surfaces throughout the system that are in constant contact with the water. The submerged roots of the vegetables combined have a large surface area, so that many bacteria can accumulate there. Together with the saliency of ammonia and nitrites in the water, the surface area determines the speed with which nitrification takes place. Care for these bacterial colonies is important as to regulate the full assimilation of ammonia and nitrite. This is why most aquaponics systems include a biofiltering unit, which helps facilitate growth of these microorganism
s. Typically, after a system has stabilized ammonia levels range from 0.25 to 2.0 ppm; nitrite levels range from 0.25 to 1 ppm, and nitrate levels range from 2 to 150 ppm. During system startup, spikes may occur in the levels of ammonia (up to 6.0 ppm) and nitrite (up to 15 ppm), with nitrate levels peaking later in the startup phase. Since the nitrification process acidifies the water, non-sodium
bases such as potassium hydroxide
or calcium hydroxide
can be added for neutralizing the water's pH
if insufficient quantities are naturally present in the water to provide a buffer against acidification. In addition, selected minerals or nutrients such as iron can be added in addition to the fish waste that serves as the main source of nutrients to plants.
A good way to deal with solids buildup in aquaponics is the use of worms, which liquefy the solid organic matter so that it can be utilized by the plants and/or animals.
Most green leaf vegetable
s grow well in the hydroponic subsystem, although most profitable are varieties of chinese cabbage
, lettuce
, basil
, rose
s, tomato
es, okra
, cantaloupe
and bell pepper
s. Other species of vegetables that grow well in an aquaponic system include bean
s, pea
s, kohlrabi, watercress
, taro
, radishes, strawberries, melon
s, onion
s, turnip
s, parsnip
s, sweet potato
and herbs. Since plants at different growth stages require different amounts of minerals and nutrients, plant harvesting is staggered with seedings growing at the same time as mature plants. This ensures stable nutrient content in the water because of continuous symbiotic cleansing of toxins from the water.
are the most popular fish for home and commercial projects that are intended to raise edible fish, although barramundi
, Silver Perch
, tandanus catfish, Jade perch and Murray cod
are also used.
by plants, evaporation into the air from surface water
, overflow from the system from rain
fall, and removal of biomass such as settled solid wastes from the system. As a result, aquaponics uses approximately 2% of the water that a conventionally irrigated farm requires for the same vegetable production. This allows for aquaponic production of both crops and fish in areas where water or fertile land is scarce. Aquaponic systems can also be used to replicate controlled wetland
conditions that are useful for water treatment by reclaiming potable water from typical household sewage
. The nutrient-filled overflow water can be accumulated in catchment tanks, and reused to accelerate growth of crops planted in soil, or it may be pumped back into the aquaponic system to top up the water level..
The three main inputs to the system are water, feed
given to the aquatic animals, and electricity to pump water between the aquaculture subsystem and the hydroponics subsystem. Spawn or fry
may be added to replace grown fish that are taken out from the system to retain a stable system. In terms of outputs, an aquaponics system may continually yield plants such as vegetables grown in hydroponics, and edible aquatic species raised in an aquaculture.
with aquaponics, other institutes followed suit. Besides the reciprocating aquaponics based on the techniques developed by Dr. Mark McMurtry et al. at the New Alchemy Institute and North Carolina State University
, Dr. James Rakocy and his colleagues at the University of the Virgin Islands
researched and developed the "Deep Water" or "Raft Culture" aquaponics The system combines tilapia with various vegetables.
In 1997 Rebecca L. Nelson and John S. Pade began publishing the Aquaponics Journal, a quarterly scientific journal that brings together research and various applications of aquaponics from around the globe. In 2008, they wrote and published the first comprehensive book on aquaponics, Aquaponic Food Production. Nelson and Pade work closely with Dr. Rakocy to bring the research on aquaponics into mainstream agriculture, and offer systems, supplies, training and consultancy professionally.
Recent years have seen a shift towards community integration of aquaponics, such as the nonprofit foundation Growing Power
that offers Milwaukee youth job opportunities and training while growing food for their community. The model has spawned several satellite projects in other cities. In 2010, a partnership of experts in sustainable agriculture was formed under the name AquaPlanet to promote the technology through media and consulting. The team includes Dr. Mark McMurtry and Barrel-Ponics inventor Travis Hughey.
with floating lettuce production, or to water fruiting vegetable crops that warm up the water too much to be recirculated back into the fish ponds. Eel
s are also known to be raised. A set-up based on the deep water system developed at the University of Virgin Islands was built in a greenhouse at Brooks, Alberta
where Dr. Nick Savidov and colleagues researched aquaponics from a background of plant science. The team made findings on rapid root growth in aquaponics systems, on closing the solid waste loop, and that because of certain advantages in the system over traditional aquaculture, the system can run well at a low pH level, which is favoured by plants but not fish. The Edmonton Aquaponics Society in Northern Alberta
is adapting Dr. Savidov's commercially sized system to a smaller scale prototype that can be operated by families, small groups, or restaurants. They intend to further develop the closed solid waste loop.
is a densely populated island that deals with water scarcity. In 40 years' time, focus has shifted from domestic fruit and vegetable production on small farms to importing 80% of all fruits and vegetables for cost reasons. Aquaponics would make Barbados and other Caribbean
islands less dependent on the world food market and reduce stress on the dwindling fish supplies. An inter-organizational project that started in late 2009 sets out to encourage and enable Barbadians to start aquaponics at home, with revenue generated by selling produce to tourists.
, native freshwater fish including silver perch
, jade perch
, sleepy cod
, murray cod
and barramundi
are popular in aquaponics and aquaculture systems, along with non-native rainbow trout
, brown trout
and crayfish
such as common yabby
and redclaw.
Some conceivable disadvantages with aquaponics are:
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
system that combines a traditional aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
(raising aquatic animal
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
s such as fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
or prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
s in tanks) with hydroponics
Hydroponics
Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk.Researchers discovered in the 18th...
(cultivating plants in water) in a symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
environment. In the aquaculture, effluent
Effluent
Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...
s accumulate in the water, increasing toxicity for the fish. This water is led to a hydroponic system where the by-product
By-product
A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced.A by-product can be useful and marketable or it can be considered waste....
s from the aquaculture are filtered out by the plants as vital nutrients, after which the cleansed water is recirculated back to the animals. The term aquaponics is a portmanteau of the terms aquaculture and hydroponic.
Aquaponic systems vary in size from small indoor or outdoor units to large commercial units, using the same technology. The systems usually contain fresh water, but salt water systems are plausible depending on the type of aquatic animal and which plants. Aquaponic science may still be considered to be at an early stage.
Function
Aquaponics consists of two main parts, with the aquaculture part for raising aquatic animals and the hydroponics part for growing plants. Aquatic effluents resulting from uneaten feed or raising animals like fish, accumulates in water due to the closed system recirculation of most aquaculture systems. The effluent-rich water becomes toxic to the aquatic animal in high concentrations but these effluents are nutrients essential for plant growth. Although consisting primarily of these two parts, aquaponics system are usually grouped into several components or subsystems responsible for the effective removal of solid wastes, for adding baseBase (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...
s to neutralize acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
s, or for maintaining water oxygenation. Typical components include:
- Rearing tank: the tanks for raising and feeding the fish;
- Solids removalSettling basinA settling basin, settling pond or decant pond are devices used to treat turbidity in industrial wastewater. The basins are used to control water pollution in diverse industries such as agriculture, aquaculture, and mining....
: a unit for catching uneaten food and detached biofilmBiofilmA biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance...
s, and for settling out fine particulates; - BiofilterBiofilterBiofiltration is a pollution control technique using living material to capture and biologically degrade process pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, and microbiotic oxidation of contaminants in air...
: a place where the nitrificationNitrificationNitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil...
bacteriaBacteriaBacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
can grow and convert ammoniaAmmoniaAmmonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
into nitrateNitrateThe nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
s, which are usable by the plants; - Hydroponics subsystem: the portion of the system where plants are grown by absorbing excess nutrients from the water;
- SumpSumpA sump is a low space that collects any often-undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers....
: the lowest point in the system where the water flows to and from which it is pumped back to the rearing tanks.
Depending on the sophistication and cost of the aquaponics system, the units for solids removal, biofiltration, and/or the hydroponics subsystem may be combined into one unit or subsystem, which prevents the water from flowing directly from the aquaculture part of the system to the hydroponics part.
Nitrification
Nitrification, the aerobicAerobic organism
An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...
conversion of ammonia into nitrates, is one of the most important functions in an aquaponics system as it reduces the toxicity of the water for fish, and allows the resulting nitrate compounds to be removed by the plants for nourishment. Ammonia is steadily released into the water through the excreta
Excretion
Excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism. This is primarily carried out by the lungs, kidneys and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell...
and gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s of fish as a product of their metabolism, but must be filtered out of the water since higher concentrations of ammonia (commonly between 0.5 and 1 ppm
Parts-per notation
In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement...
) can kill fish. Although plants can absorb ammonia from the water to some degree, nitrates are assimilated more easily, thereby efficiently reducing the toxicity of the water for fish. Ammonia can be converted into other nitrogenous compounds through healthy populations of:
- NitrosomonasNitrosomonasNitrosomonas is a genus comprising rod shaped chemoautotrophic bacteria.This rare bacteria oxidizes ammonia into nitrite as a metabolic process. Nitrosomonas are useful in treatment of industrial and sewage waste and in the process of bioremediation. They are important in the nitrogen cycle by...
: bacteria that convert ammonia into nitriteNitriteThe nitrite ion has the chemical formula NO2−. The anion is symmetric with equal N-O bond lengths and a O-N-O bond angle of ca. 120°. On protonation the unstable weak acid nitrous acid is produced. Nitrite can be oxidised or reduced, with product somewhat dependent on the oxidizing/reducing agent...
s, and - NitrobacterNitrobacterNitrobacter is genus of mostly rod-shaped, gram-negative, and chemoautotrophic bacteria.Nitrobacter plays an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil...
: bacteria that convert nitrites into nitrates.
In an aquaponics system, the bacteria responsible for this process form a biofilm
Biofilm
A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance...
on all solid surfaces throughout the system that are in constant contact with the water. The submerged roots of the vegetables combined have a large surface area, so that many bacteria can accumulate there. Together with the saliency of ammonia and nitrites in the water, the surface area determines the speed with which nitrification takes place. Care for these bacterial colonies is important as to regulate the full assimilation of ammonia and nitrite. This is why most aquaponics systems include a biofiltering unit, which helps facilitate growth of these microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
s. Typically, after a system has stabilized ammonia levels range from 0.25 to 2.0 ppm; nitrite levels range from 0.25 to 1 ppm, and nitrate levels range from 2 to 150 ppm. During system startup, spikes may occur in the levels of ammonia (up to 6.0 ppm) and nitrite (up to 15 ppm), with nitrate levels peaking later in the startup phase. Since the nitrification process acidifies the water, non-sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
bases such as potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
or calcium hydroxide
Calcium hydroxide
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a colourless crystal or white powder and is obtained when calcium oxide is mixed, or "slaked" with water. It has many names including hydrated lime, builders lime, slack lime, cal, or...
can be added for neutralizing the water's pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
if insufficient quantities are naturally present in the water to provide a buffer against acidification. In addition, selected minerals or nutrients such as iron can be added in addition to the fish waste that serves as the main source of nutrients to plants.
A good way to deal with solids buildup in aquaponics is the use of worms, which liquefy the solid organic matter so that it can be utilized by the plants and/or animals.
Hydroponics subsystem
Plants are grown as in hydroponics systems, with their roots immersed in the nutrient-rich effluent water. This enables them to filter out the ammonia that is toxic to the aquatic animals, or its metabolites. After the water has passed through the hydroponic subsystem, it is cleaned and oxygenated, and can return to the aquaculture vessels. This cycle is continuous. Common aquaponic applications of hydroponic systems include:- Deep-water raft aquaponics: styrofoamStyrofoamStyrofoam is a trademark of The Dow Chemical Company for closed-cell currently made for thermal insulation and craft applications. In 1941, researchers in Dow's Chemical Physics Lab found a way to make foamed polystyrene...
rafts floating in a relatively deep aquaculture basin in troughs. - Recirculating aquaponics: solid media such as gravelGravelGravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...
or clayClayClay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
beads, held in a container that is flooded with water from the aquaculture. This type of aquaponics is also known as closed-loop aquaponics. - Reciprocating aquaponics: solid media in a container that is alternately flooded and drained utilizing different types of siphon drains. This type of aquaponics is also known as flood-and-drain aquaponics or ebb-and-flow aquaponics.
- Other systems use towers that are trickle-fed from the top, nutrient film techniqueNutrient film techniqueNutrient Film Technique or NFT is a hydroponic technique wherein a very shallow stream of water containing all the dissolved nutrients required for plant growth is re-circulated past the bare roots of plants in a watertight gully, also known as channels...
channels, horizontal PVCPolyvinyl chloridePolyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
pipes with holes for the pots, plastic barrels cut in half with gravel or rafts in them. Each approach has its own benefits.
Most green leaf vegetable
Leaf vegetable
Leaf vegetables, also called potherbs, green vegetables, greens, leafy greens or salad greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots...
s grow well in the hydroponic subsystem, although most profitable are varieties of chinese cabbage
Chinese cabbage
Chinese cabbage can refer to two distinct varieties of Chinese leaf vegetables used often in Chinese cuisine. These vegetables are both related to the Western cabbage, and are of the same species as the common turnip...
, lettuce
Lettuce
Lettuce is a temperate annual or biennial plant of the daisy family Asteraceae. It is most often grown as a leaf vegetable. It is eaten either raw, notably in salads, sandwiches, hamburgers, tacos, and many other dishes, or cooked, as in Chinese cuisine in which the stem becomes just as important...
, basil
Basil
Basil, or Sweet Basil, is a common name for the culinary herb Ocimum basilicum , of the family Lamiaceae , sometimes known as Saint Joseph's Wort in some English-speaking countries....
, rose
Rose
A rose is a woody perennial of the genus Rosa, within the family Rosaceae. There are over 100 species. They form a group of erect shrubs, and climbing or trailing plants, with stems that are often armed with sharp prickles. Flowers are large and showy, in colours ranging from white through yellows...
s, tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es, okra
Okra
Okra is a flowering plant in the mallow family. It is valued for its edible green seed pods. The geographical origin of okra is disputed, with supporters of South Asian, Ethiopian and West African origins...
, cantaloupe
Cantaloupe
"Rockmelon" redirects here, for the band see Rockmelons. See also Cantaloupe .Cantaloupe refers to a variety of Cucumis melo, a species in the family Cucurbitaceae which includes nearly all melons and squashes. Cantaloupes range in size from...
and bell pepper
Bell pepper
Bell pepper, also known as sweet pepper or a pepper and capsicum , is a cultivar group of the species Capsicum annuum . Cultivars of the plant produce fruits in different colors, including red, yellow, orange and green. Bell peppers are sometimes grouped with less pungent pepper varieties as...
s. Other species of vegetables that grow well in an aquaponic system include bean
Bean
Bean is a common name for large plant seeds of several genera of the family Fabaceae used for human food or animal feed....
s, pea
Pea
A pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum. Each pod contains several peas. Peapods are botanically a fruit, since they contain seeds developed from the ovary of a flower. However, peas are considered to be a vegetable in cooking...
s, kohlrabi, watercress
Watercress
Watercresses are fast-growing, aquatic or semi-aquatic, perennial plants native from Europe to central Asia, and one of the oldest known leaf vegetables consumed by human beings...
, taro
Taro
Taro is a common name for the corms and tubers of several plants in the family Araceae . Of these, Colocasia esculenta is the most widely cultivated, and is the subject of this article. More specifically, this article describes the 'dasheen' form of taro; another variety is called eddoe.Taro is...
, radishes, strawberries, melon
Melon
thumb|200px|Various types of melonsThis list of melons includes members of the plant family Cucurbitaceae with edible, fleshy fruit e.g. gourds or cucurbits. The word "melon" can refer to either the plant or specifically to the fruit...
s, onion
Onion
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...
s, turnip
Turnip
The turnip or white turnip is a root vegetable commonly grown in temperate climates worldwide for its white, bulbous taproot. Small, tender varieties are grown for human consumption, while larger varieties are grown as feed for livestock...
s, parsnip
Parsnip
The parsnip is a root vegetable related to the carrot. Parsnips resemble carrots, but are paler than most carrots and have a sweeter taste, especially when cooked. The buttery, slightly spicy, sweet flavor of cooked mature parsnips is reminiscent of butterscotch, honey, and subtle cardamom...
s, sweet potato
Sweet potato
The sweet potato is a dicotyledonous plant that belongs to the family Convolvulaceae. Its large, starchy, sweet-tasting, tuberous roots are an important root vegetable. The young leaves and shoots are sometimes eaten as greens. Of the approximately 50 genera and more than 1,000 species of...
and herbs. Since plants at different growth stages require different amounts of minerals and nutrients, plant harvesting is staggered with seedings growing at the same time as mature plants. This ensures stable nutrient content in the water because of continuous symbiotic cleansing of toxins from the water.
Aquaculture subsystem
Freshwater fish are the most common aquatic animal raised using aquaponics, although saltwater fish, crayfish and prawns may also be used. In practice, tilapiaTilapia
Tilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...
are the most popular fish for home and commercial projects that are intended to raise edible fish, although barramundi
Barramundi
The Barramundi , also known as Asian Seabass, is a species of catadromous fish in family Latidae of order Perciformes. The native species is widely distributed in the Indo-West Pacific region from the Persian Gulf, through Southeast Asia to Papua New Guinea and Northern Australia. Known in Thai...
, Silver Perch
Silver Perch
Silver perch is a medium sized freshwater fish endemic to the Murray-Darling river system in south-eastern Australia. The scientific name comes from an aboriginal name for the species recorded by Major Mitchell on his 1832 expedition. It is not a perch, being a grunter in the family Terapontidae...
, tandanus catfish, Jade perch and Murray cod
Murray Cod
The Murray cod is a large Australian predatory freshwater fish of the Maccullochella genus and the Percichthyidae family. Although the species is a called cod in the vernacular, it is not related to the northern hemisphere marine cod species...
are also used.
Normal operations
Aquaponic systems do not typically discharge or exchange water under normal operation, but instead recirculate and reuse water very effectively. The system relies on the relationship between the animals and the plants to maintain a stable aquatic environment that experience a minimum of fluctuation in ambient nutrient and oxygen levels. Water is only added to replace water loss from absorption and transpirationTranspiration
Transpiration is a process similar to evaporation. It is a part of the water cycle, and it is the loss of water vapor from parts of plants , especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings which are collectively called stomata, and in most plants...
by plants, evaporation into the air from surface water
Surface water
Surface water is water collecting on the ground or in a stream, river, lake, wetland, or ocean; it is related to water collecting as groundwater or atmospheric water....
, overflow from the system from rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
fall, and removal of biomass such as settled solid wastes from the system. As a result, aquaponics uses approximately 2% of the water that a conventionally irrigated farm requires for the same vegetable production. This allows for aquaponic production of both crops and fish in areas where water or fertile land is scarce. Aquaponic systems can also be used to replicate controlled wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
conditions that are useful for water treatment by reclaiming potable water from typical household sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...
. The nutrient-filled overflow water can be accumulated in catchment tanks, and reused to accelerate growth of crops planted in soil, or it may be pumped back into the aquaponic system to top up the water level..
The three main inputs to the system are water, feed
Compound feed
Compound feeds are feedstuffs that are blended from various raw materials and additives. These blends are formulated according to the specific requirements of the target animal...
given to the aquatic animals, and electricity to pump water between the aquaculture subsystem and the hydroponics subsystem. Spawn or fry
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
may be added to replace grown fish that are taken out from the system to retain a stable system. In terms of outputs, an aquaponics system may continually yield plants such as vegetables grown in hydroponics, and edible aquatic species raised in an aquaculture.
Ancient
Aquaponics has ancient roots, although there is some debate on its first occurrence:- AztecAztecThe Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...
cultivated agricultural islands known as chinampaChinampaChinampa is a method of ancient Mesoamerican agriculture which used small, rectangle-shaped areas of fertile arable land to grow crops on the shallow lake beds in the Valley of Mexico.-Description:...
s and are considered by some as the first form of aquaponics for agricultural use, where plants were raised on stationary (and sometime movable) islands in lake shallows and waste materials dredged from the Chinampa canals and surrounding cities are used to manually irrigate the plants - South ChinaChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
who cultivated and farmed rice in paddy fieldPaddy fieldA paddy field is a flooded parcel of arable land used for growing rice and other semiaquatic crops. Paddy fields are a typical feature of rice farming in east, south and southeast Asia. Paddies can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such...
s in combination with fish are cited as examples of early aquaponics. These polyculturalPolyculturePolyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...
farming systems existed in many Far EastFar EastThe Far East is an English term mostly describing East Asia and Southeast Asia, with South Asia sometimes also included for economic and cultural reasons.The term came into use in European geopolitical discourse in the 19th century,...
ern countries and raised fish such as the oriental loach (泥鳅, ドジョウ), swamp eelMonopterus albusMonopterus albus is an important air-breathing commercial species of fish in the Synbranchidae family...
(黄鳝, 田鰻), CommonCommon carpThe Common carp is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive...
(鯉魚, コイ) and crucian carpCrucian carpThe crucian carp is a member of the family Cyprinidae, which includes many other fish, such as the common carp, or the smaller minnows. They inhabit lakes, ponds, and slow-moving rivers throughout Europe and Asia. The crucian is a medium-sized cyprinid, which rarely exceeds a weight of over 3.3...
(鯽魚) as well as pond snailViviparidaeViviparidae, sometimes known as the river snails or mystery snails, are a family of large operculate freshwater snails, aquatic gastropod mollusks....
s (田螺) in the paddies.
United States
Inspired by the successes of the New Alchemy Institute and the North Carolina State UniversityNorth Carolina State University
North Carolina State University at Raleigh is a public, coeducational, extensive research university located in Raleigh, North Carolina, United States. Commonly known as NC State, the university is part of the University of North Carolina system and is a land, sea, and space grant institution...
with aquaponics, other institutes followed suit. Besides the reciprocating aquaponics based on the techniques developed by Dr. Mark McMurtry et al. at the New Alchemy Institute and North Carolina State University
North Carolina State University
North Carolina State University at Raleigh is a public, coeducational, extensive research university located in Raleigh, North Carolina, United States. Commonly known as NC State, the university is part of the University of North Carolina system and is a land, sea, and space grant institution...
, Dr. James Rakocy and his colleagues at the University of the Virgin Islands
University of the Virgin Islands
The University of the Virgin Islands is a public university located in the United States Virgin Islands.-Academics:The university has five academic divisions: Business, Education, Humanities and Social Sciences, Nursing, and Science and Mathematics. UVI offers several graduate degree programs and...
researched and developed the "Deep Water" or "Raft Culture" aquaponics The system combines tilapia with various vegetables.
In 1997 Rebecca L. Nelson and John S. Pade began publishing the Aquaponics Journal, a quarterly scientific journal that brings together research and various applications of aquaponics from around the globe. In 2008, they wrote and published the first comprehensive book on aquaponics, Aquaponic Food Production. Nelson and Pade work closely with Dr. Rakocy to bring the research on aquaponics into mainstream agriculture, and offer systems, supplies, training and consultancy professionally.
Recent years have seen a shift towards community integration of aquaponics, such as the nonprofit foundation Growing Power
Growing Power
Growing Power is an urban agriculture organization headquartered in Milwaukee, Wisconsin. It runs the last functional farm within the Milwaukee city limits and also organizes activities in Chicago...
that offers Milwaukee youth job opportunities and training while growing food for their community. The model has spawned several satellite projects in other cities. In 2010, a partnership of experts in sustainable agriculture was formed under the name AquaPlanet to promote the technology through media and consulting. The team includes Dr. Mark McMurtry and Barrel-Ponics inventor Travis Hughey.
Canada
The first aquaponics research in Canada was a small system added onto existing aquaculture research at a research station in Lethbridge. Canada saw a rise in aquaponics setups throughout the 90s, predominantly as commercial installations, that for example combine troutTrout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
with floating lettuce production, or to water fruiting vegetable crops that warm up the water too much to be recirculated back into the fish ponds. Eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
s are also known to be raised. A set-up based on the deep water system developed at the University of Virgin Islands was built in a greenhouse at Brooks, Alberta
Brooks, Alberta
Brooks is a city in southeast Alberta, Canada surrounded by the County of Newell. It is located on Highway 1 and the Canadian Pacific Railway, approximately southeast of Calgary, and northwest of Medicine Hat. The city has an elevation of .- History :The area that is now Brooks was originally...
where Dr. Nick Savidov and colleagues researched aquaponics from a background of plant science. The team made findings on rapid root growth in aquaponics systems, on closing the solid waste loop, and that because of certain advantages in the system over traditional aquaculture, the system can run well at a low pH level, which is favoured by plants but not fish. The Edmonton Aquaponics Society in Northern Alberta
Northern Alberta
Northern Alberta is a region located in the Canadian province of Alberta.Its primary industry is oil and gas, with large heavy oil reserves being exploited at the Athabasca Oil Sands and Wabasca Area in the east of the region...
is adapting Dr. Savidov's commercially sized system to a smaller scale prototype that can be operated by families, small groups, or restaurants. They intend to further develop the closed solid waste loop.
Barbados
BarbadosBarbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
is a densely populated island that deals with water scarcity. In 40 years' time, focus has shifted from domestic fruit and vegetable production on small farms to importing 80% of all fruits and vegetables for cost reasons. Aquaponics would make Barbados and other Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
islands less dependent on the world food market and reduce stress on the dwindling fish supplies. An inter-organizational project that started in late 2009 sets out to encourage and enable Barbadians to start aquaponics at home, with revenue generated by selling produce to tourists.
Taiwan
Taiwan is a densely populated island that is faced with freshwater scarcity. Dispensation of water is government-controlled. The closed-loop system of aquaponics is used by agricultural farmers to save water by also rearing fish, while fish farmers grow plants that filter the water from the fish tanks.Australia
Due to a ban on tilapia in all states except for Western AustraliaWestern Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, native freshwater fish including silver perch
Silver Perch
Silver perch is a medium sized freshwater fish endemic to the Murray-Darling river system in south-eastern Australia. The scientific name comes from an aboriginal name for the species recorded by Major Mitchell on his 1832 expedition. It is not a perch, being a grunter in the family Terapontidae...
, jade perch
Barcoo grunter
The Barcoo grunter or jade perch, Scortum barcoo, is a species of fish in the Terapontidae family, that is found in major rivers in Australia. Jade perch are currently bred for aquarium trade and for human consumption.-Characteristics:...
, sleepy cod
Sleepy cod
The sleepy cod, Oxyeleotris lineolatus, is a medium-sized freshwater fish, native to tropical regions of northern Australia.Sleepy cod generally weigh up to 3 kg. They are very common in waterways across northern Australia. They are plain brown coloured fishes. They are sedentary in nature...
, murray cod
Murray Cod
The Murray cod is a large Australian predatory freshwater fish of the Maccullochella genus and the Percichthyidae family. Although the species is a called cod in the vernacular, it is not related to the northern hemisphere marine cod species...
and barramundi
Barramundi
The Barramundi , also known as Asian Seabass, is a species of catadromous fish in family Latidae of order Perciformes. The native species is widely distributed in the Indo-West Pacific region from the Persian Gulf, through Southeast Asia to Papua New Guinea and Northern Australia. Known in Thai...
are popular in aquaponics and aquaculture systems, along with non-native rainbow trout
Rainbow trout
The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....
, brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....
and crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
such as common yabby
Common yabby
The common yabby, Cherax destructor, is an Australian freshwater crustacean in the Parastacidae family. It is listed as a vulnerable species of crayfish by the World Conservation Union , though the validity of this listing is questionable; wild yabby populations remain strong, and have expanded...
and redclaw.
Pros and cons
The unique advantages of aquaponic systems are:- Conservation through constant water reuse and recycling.
- Organic fertilization of plants with natural fish emulsion.
- The elimination of solid waste disposal from intensive aquaculture.
- The reduction of needed cropland to produce crops.
- The overall reduction of the environmental footprint of crop production.
- Building small efficient commercial installations near markets reduces food milesFood milesFood miles is a term which refers to the distance food is transported from the time of its production until it reaches the consumer. Food miles are one factor used when assessing the environmental impact of food, including the impact on global warming....
. - Reduction of pathogens that often plague aquaculture production systems.
Some conceivable disadvantages with aquaponics are:
- Initial expenses for housing, tank, plumbing, pumps, and grow beds.
- The infinite number of ways in which a system can be configured lends itself to equally varying results, conflicting research, and successes or failures.
- Some aquaponic installations rely heavily on man-made energy, technological solutions, and environmental control to achieve recirculation and water/ambient temperatures. However, if a system is designed with energy conservation in mind, using alternative energyAlternative energyAlternative energy is an umbrella term that refers to any source of usable energy intended to replace fuel sources without the undesired consequences of the replaced fuels....
and a reduced number of pumps by letting the water flow downwards as much as possible, it can be highly energy efficient. - While careful design can minimize the risk, aquaponics systems can have multiple 'single points of failure' where problems such as an electrical failure or a pipe blockage can lead to a complete loss of fish stock.
- Like all aquaculture based systems, stock feed usually consists of fish meal derived from lower value species. Ongoing depletion of wild fish stocks makes this practice unsustainable. Organic fish feeds may prove to be a viable alternative that negates this concern. Other alternatives include growing duckweed with an aquaponics system that feeds the same fish grown on the system, excess worms grown from vermiculture composting, as well as growing black soldier flyHermetia illucensThe black soldier fly, Hermetia illucens, is a common and widespread fly of the family Stratiomyidae, whose larvae are common detritivores in compost heaps...
larvae to feed to the fish using composting grub growers.
See also
- AquacultureAquacultureAquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
- HorticultureHorticultureHorticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic...
- HydroponicsHydroponicsHydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk.Researchers discovered in the 18th...
- MicroponicsMicroponicsMicroponics is the symbiotic integration of fish, plants and micro-livestock in a semi-controlled environment.-History:Microponics is a term created recently by Australian urban farmer, Gary Donaldson to describe his integrated backyard food production concept.While Microponics was also the name...
- PermaculturePermaculturePermaculture is an approach to designing human settlements and agricultural systems that is modeled on the relationships found in nature. It is based on the ecology of how things interrelate rather than on the strictly biological concerns that form the foundation of modern agriculture...
- SymbiosisSymbiosisSymbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...