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Ecological efficiency is a combination of several related efficiencies that describe resource utilization and the extent to which resources are converted into biomass. [ 1 ] Exploitation efficiency is the amount of food ingested divided by the amount of prey production ( I n / P n − 1 {\displaystyle I_{n}/P_{n-1}} )
The efficiency with which energy or biomass is transferred from one trophic level to the next is called the ecological efficiency. Consumers at each level convert on average only about 10% of the chemical energy in their food to their own organic tissue (the ten-per cent law). For this reason, food chains rarely extend for more than 5 or 6 levels.
Thus, some consider harvesting at MSY to be unsafe on ecological and economic grounds. [ 14 ] [ 15 ] The MSY model itself can be modified to harvest a certain percentage of the population or with constant effort constraints rather than an actual number, thereby avoiding some of its instabilities.
Typical units are grams per square meter per year or calories per square meter per year. As with the others, this graph shows producers at the bottom and higher trophic levels on top. When an ecosystem is healthy, this graph produces a standard ecological pyramid. This is because, in order for the ecosystem to sustain itself, there must be more ...
Ecological efficiency may be anywhere from 5% to 20% depending on how efficient or inefficient that ecosystem is. [ 8 ] [ 1 ] This decrease in efficiency occurs because organisms need to perform cellular respiration to survive, and energy is lost as heat when cellular respiration is performed. [ 1 ]
Carlson's index was proposed by Robert Carlson in his 1977 seminal paper, "A trophic state index for lakes". [3] It is one of the more commonly used trophic indices and is the trophic index used by the United States Environmental Protection Agency. [2]
Ecological yield is the harvestable population growth of an ecosystem. It is most commonly measured in forestry : sustainable forestry is defined as that which does not harvest more wood in a year than has grown in that year, within a given patch of forest .
EwE has three main components: Ecopath – a static, mass-balanced snapshot of the system [2]; Ecosim – a time dynamic simulation module for policy exploration [3]; Ecospace – a spatial and temporal dynamic module designed for exploring the combined impacts of fishing, the placement of protected areas, [4] and changing environmental conditions.