Closed ecological systems orcontained ecological systems (CES) areecosystems that do not rely on matter exchange with any part outside the system.
The term is most often used to describe small, man-made ecosystems. Such systems can potentially serve as alife-support system orspace habitats.[1]
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 amouse or ahuman, waste products such ascarbon dioxide,feces andurine must eventually be converted intooxygen,food, andwater.
A closed ecological system must contain at least oneautotrophic organism. While bothchemotrophic andphototrophic organisms are plausible, almost all closed ecological systems to date are based on an autotroph such as greenalgae.
A closed ecological system for an entire planet is called anecosphere.[2][3]
Man-made closed ecological systems which were created to sustain human life includeBiosphere 2,MELiSSA, and the BIOS-1, BIOS-2, andBIOS-3 projects.[4]
Bottle gardens andaquarium ecospheres are partially or fully enclosed glass containers that are self-sustaining closed ecosystems that can be made or purchased. They can include tinyshrimp,algae,gravel, decorativeshells, andGorgonia.[5]
Closed ecological systems are commonly featured in fiction and particularly inscience fiction. These includedomed cities,space stations and habitats on foreign planets or asteroids, cylindrical habitats (e.g.O'Neill cylinders),Dyson Spheres and so on.[6]
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