Closed ecological systems (CES) are

ecosystems An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

that do not rely on matter exchange with any part outside the system. The term is most often used to describe small,

manmade Artificiality (the state of being artificial or manmade) is the state of being the product of intentional human manufacture, rather than occurring naturally through processes not involving or requiring human activity. Connotations Artificiality ...

ecosystems. Such systems are scientifically interesting and can potentially serve as a

life-support system A life-support system is the combination of equipment that allows survival in an environment or situation that would not support that life in its absence. It is generally applied to systems supporting human life in situations where the outsid ...

during

space flight Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in ...

s, in

space stations A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station is ...

or space habitats. In a closed ecological system, any waste products produced by one species must be used by at least one other species. If the purpose is to maintain a life form, such as a

mouse A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

or a

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

, waste products such as

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

, feces and

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...

must eventually be converted into

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...

, and

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. A closed ecological system must contain at least one

autotroph An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Works", ...

ic organism. While both

chemotroph A Chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic ( chemolithotrophs). The chemotroph designation is in contrast to phototr ...

ic and

phototroph Phototrophs () are organisms that carry out photon capture to produce complex organic compounds (e.g. carbohydrates) and acquire energy. They use the energy from light to carry out various cellular metabolic processes. It is a common misconcep ...

ic organisms are plausible, almost all closed ecological systems to date are based on an autotroph such as green

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

Examples

A closed ecological system for an entire planet is called an ecosphere. Man-made closed ecological systems which were created to sustain human life include

Biosphere 2 Biosphere 2 is an American Earth system science research facility located in Oracle, Arizona. Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the univers ...

MELiSSA Melissa is a female given name. The name comes from the Greek word μέλισσα (''mélissa''), "bee", which in turn comes from μέλι (''meli''), "honey". In Hittite, ''melit'' signifies "honey". ''Melissa'' also refers to the plant ''Me ...

, and the BIOS-1, BIOS-2, and

BIOS-3 BIOS-3 is an experimental closed ecosystem at the Institute of Biophysics in Krasnoyarsk, Russia. Its construction began in 1965, and was completed in 1972. BIOS-3 consists of a underground steel structure suitable for up to three persons, and ...

projects.

Bottle garden A bottle garden is a type of closed terrarium in which plants are grown. They usually consist of a plastic or glass bottle with a narrow neck and a small opening. Plants are grown inside the bottle with little or no exposure to the outside enviro ...

s and aquarium ecospheres are partially or fully enclosed glass containers that are self-sustaining closed ecosystems that can be made or purchased. They can include tiny

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

, decorative

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

s, and ''

Gorgonia ''Gorgonia'' is a genus of soft corals, sea fans in the family Gorgoniidae. Species The World Register of Marine Species lists these species In biology, a species is the basic unit of classification and a taxonomic rank of an organi ...

''.

In fiction

References

Emerging technologies Ecological processes Systems ecology {{Space-stub

Examples

In fiction

See also

References