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The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way ...
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 energy at lower trophic levels than there is at higher trophic levels.
Each trophic level transforms energy into biomass. Energy flow diagrams illustrate the rates and efficiency of transfer from one trophic level into another and up through the hierarchy. [36] [37] It is the case that the biomass of each trophic level decreases from the base of the chain to the top.
Of all the net primary productivity at the producer trophic level, in general only 10% goes to the next level, the primary consumers, then only 10% of that 10% goes on to the next trophic level, and so on up the food pyramid. [1] Ecological efficiency may be anywhere from 5% to 20% depending on how efficient or inefficient that ecosystem is.
The definition of the trophic level, TL, for any consumer species is [6] = + (), where is the fractional trophic level of the prey j, and represents the fraction of j in the diet of i. In the case of marine ecosystems, the trophic level of most fish and other marine consumers takes value between 2.0 and 5.0.
The mean trophic level is calculated by assigning each fish or invertebrate species a number based on its trophic level.The trophic level is a measure of the position of an organism in a food web, starting at level 1 with primary producers, such as phytoplankton and seaweed, then moving through the primary consumers at level 2 that eat the primary producers to the secondary consumers at level ...
Trophic coherence is a property of directed graphs (or directed networks). [1] It is based on the concept of trophic levels used mainly in ecology, [2] but which can be defined for directed networks in general and provides a measure of hierarchical structure among nodes. Trophic coherence is the tendency of nodes to fall into well-defined ...
Trophic coherence: The tendency of species to specialise on particular trophic levels leads to food webs displaying a significant degree of order in their trophic structure, known as trophic coherence, [22] which in turn has important effects on properties such as stability and prevalence of cycles.