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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 ...
In the simplest scheme, the first trophic level (level 1) is plants, then herbivores (level 2), and then carnivores (level 3). The trophic level equals one more than the chain length, which is the number of links connecting to the base. The base of the food chain (primary producers or detritivores) is set at zero.
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
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 ...
The split does not seem to have been driven by competition for resources, but instead because each species adopted a different ecological niche and occupied a different trophic level. [20] [failed verification] Blue wildebeest fossils dating back some 2.5 million years ago are common and widespread.
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.
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.
Thus, the net production at one trophic level is / / / = / or approximately ten percent that of the trophic level before it. For example, assume 500 units of energy are produced by trophic level 1. One half of that is lost to non-predatory death, while the other half (250 units) is ingested by trophic level 2.