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That is, the consumer trophic level is one plus the weighted average of how much different trophic levels contribute to its food. In the case of marine ecosystems, the trophic level of most fish and other marine consumers takes a value between 2.0 and 5.0.
Energy pyramids are necessarily upright in healthy ecosystems, that is, there must always be more energy available at a given level of the pyramid to support the energy and biomass requirement of the next trophic level. An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical ...
The energy converted through photosynthesis is carried through the trophic levels of an ecosystem as organisms consume members of lower trophic levels. Primary production can be broken down into gross and net primary production. Gross primary production is a measure of the energy that a photoautotroph harvests from the sun.
The intermediate levels are filled with omnivores that feed on more than one trophic level and cause energy to flow through several food pathways starting from a basal species. [14] In the simplest scheme, the first trophic level (level 1) is plants, then herbivores (level 2), and then carnivores (level 3).
Among aquatic and terrestrial ecosystems, patterns have been identified that can account for this variation and have been divided into two main pathways of control: top-down and bottom-up. [22] [23] The acting mechanisms within each pathway ultimately regulate community and trophic level structure within an ecosystem to varying degrees. [24]
Each of these constitutes a trophic level. [15] The sequence of consumption—from plant to herbivore, to carnivore—forms a food chain. Real systems are much more complex than this—organisms will generally feed on more than one form of food, and may feed at more than one trophic level.
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 concept of trophic levels are used in food webs to visualise the manner in which energy is transferred from one part of an ecosystem to another. [29] Trophic levels can be assigned numbers determining how far an organism is along the food chain .