Detritus
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In
Theory
The corpses of dead plants or animals, material derived from animal tissues (e.g.,
In ecosystems on land, detritus is deposited on the surface of the ground, taking forms such as the humic soil beneath a layer of fallen leaves. In aquatic ecosystems, most detritus is suspended in water, and gradually settles. In particular, many different types of material are collected together by currents, and much material settles in slowly flowing areas.
A large amount of detritus is used as a source of nutrition for
A characteristic type of
What is left behind by the detritivores is then further broken down and recycled by
This detritus cycle plays a large part in the so-called purification process, whereby organic materials carried in by rivers is broken down and disappears, and an extremely important part in the breeding and growth of marine resources. In ecosystems on land, far more essential material is broken down as dead material passing through the detritus chain than is broken down by being eaten by animals in a living state. In both land and aquatic ecosystems, the role played by detritus is too large to ignore.
Aquatic ecosystems
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In contrast to land ecosystems, dead materials and excreta in aquatic ecosystems are typically transported by water flow; finer particles tend to be transported farther or suspended longer. In freshwater bodies organic material from plants can form a silt known as mulm or humus on the bottom. This material, some called undissolved organic carbon breaks down into dissolved organic carbon and can bond to heavy metal ions via chelation. It can also break down into colored dissolved organic matter such as tannin, a specific form of tannic acid. In saltwater bodies, organic material breaks down and forms a marine snow. This example of detritus commonly consists of organic materials such as dead phytoplankton and zooplankton, the outer walls of diatoms and coccolithophores, dead skin and scales of fish, and fecal pellets. This material will slowly sink to the seafloor, where it makes up the majority of sediment in some areas. Once settled, the material will not only contribute to sediments but will help to feed different species of detritivore, organisms which feed on detritus, such as annelid worms and sea cucumbers, to name a few. The exact composition of this detritus varies based on location and time of year, as it is very closely tied to primary production.
Terrestrial ecosystems
Detritus occurs in a variety of terrestrial habitats including forest, chaparral and grassland. In forests, the detritus is typically dominated by leaf, twig, and bacteria litter as measured by biomass dominance. This
Consumers
There is an extremely large number of
Another more widely used method of feeding, which also incorporates filter feeding, is a system where an organism secretes mucus to catch the detritus in lumps, and then carries these to its mouth using an area of
Many organisms, including sea slugs and serpent's starfish, scoop up the detritus which has settled on the water bed. Bivalves which live inside the water bed do not simply suck in water through their tubes, but also extend them to fish for detritus on the surface of the bed.
Producers
In contrast, from the point of view of organisms using photosynthesis such as
In land ecosystems, the waste products of plants and animals collect mainly on the ground (or on the surfaces of trees), and as decomposition proceeds, plants are supplied with fertilizer in the form of inorganic salts. In water ecosystems, relatively little waste collects on the water bed, and so the progress of decomposition in water takes a more important role. Investigating the level of inorganic salts in sea ecosystems shows that unless there is an especially large supply, the quantity increases from winter to spring—but is normally extremely low in summer. As such, the quantity of seaweed present reaches a peak in early summer and then decreases. The thinking is that organisms like plants grow quickly in warm periods and thus the quantity of inorganic salts is not enough to keep up with the demand. In other words, during winter, plant-like organisms are inactive and collect fertilizer, but if the temperature rises to some extent they will use this up in a very short period.
It is not entirely true that their productivity falls during the warmest periods. Organisms such as dinoflagellate have mobility, the ability to take in solid food, and the ability to photosynthesise. This type of micro-organism can take in substances such as detritus to grow, without waiting for it to be broken down into fertilizer.
Aquariums
In recent years, the word detritus has also come to be used in relation to aquariums (the word "aquarium" is a general term for any installation for keeping aquatic animals).
When animals such as fish are kept in an aquarium, substances such as excreta, mucus and dead skin cast off during moulting are produced by the animals and, naturally, generate detritus, and are continually broken down by micro-organisms.
Modern sealife aquariums often use the Berlin Method, which employs a piece of equipment called a protein skimmer, which produces air bubbles which the detritus adheres to, and forces it outside the tank before it decomposes, and also a highly porous type of natural rock called live rock where many benthos and bacteria live (hermatype which has been dead for some time is often used), which causes the detritus-feeding benthos and micro-organisms to undergo a detritus cycle. The Monaco system, where an anaerobic layer is created in the tank, to denitrify the organic compounds in the tank, and also the other nitrogen compounds, so that the decomposition process continues until the stage where water, carbon dioxide and nitrogen are produced, has also been implemented.
Initially, the filtration systems in water tanks often worked as the name suggests, using a physical filter to remove foreign substances in the water. Following this, the standard method for maintaining the water quality was to convert ammonium or nitrates in excreta, which have a high degree of neurotoxicity, but the combination of detritus feeders, detritus and micro-organisms has now brought aquarium technology to a still higher level.
See also
- Biofact (biology)
- Coarse woody debris
- Organic material
- Soil food web
Citations
- ^ "Decomposition and decay". Trees for Life. Retrieved 2024-05-30.
- ^ C.M. Hogan, 2008
- ^ D.A. Grimaldi, 2005
- ^ B.C. Patten, 1975
Sources
![]() | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (November 2012) |
- Bernard C. Patten (1975) Systems Analysis and Simulation in Ecology, Academic Press, 607 pages ISBN 0-12-547203-X
- C. Michael Hogan (2008) "Western fence lizard (Sceloporus occidentalis)", Globaltwitcher, ed. Nicklas Stromberg [1]
- David Author Grimaldi and Michael S. Author (2005) Engelevolution of the insects, Cambridge University Press ISBN 0-521-82149-5
- Some of this article was translated from the equivalent article in the Japanese-language Wikipedia, as it was on September 1, 2006.
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