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  2. Ecological pyramid - Wikipedia

    en.wikipedia.org/wiki/Ecological_pyramid

    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.

  3. Trophic level - Wikipedia

    en.wikipedia.org/wiki/Trophic_level

    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.

  4. Ecological efficiency - Wikipedia

    en.wikipedia.org/wiki/Ecological_efficiency

    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.

  5. Energy flow (ecology) - Wikipedia

    en.wikipedia.org/wiki/Energy_flow_(ecology)

    In order to more efficiently show the quantity of organisms at each trophic level, these food chains are then organized into trophic pyramids. [1] The arrows in the food chain show that the energy flow is unidirectional, with the head of an arrow indicating the direction of energy flow; energy is lost as heat at each step along the way.

  6. Food web - Wikipedia

    en.wikipedia.org/wiki/Food_web

    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).

  7. Trophic cascade - Wikipedia

    en.wikipedia.org/wiki/Trophic_cascade

    Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce the abundance, or alter the behavior of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate ...

  8. Ecological unit - Wikipedia

    en.wikipedia.org/wiki/Ecological_unit

    Ecological units refer to specific levels or degrees of organization within ecological systems. The units that are most commonly used and discussed within ecological systems are those at the levels of individuals, populations, communities, and ecosystems. [1]

  9. Lake ecosystem - Wikipedia

    en.wikipedia.org/wiki/Lake_ecosystem

    Lentic ecosystems can be compared with lotic ecosystems, which involve flowing terrestrial waters such as rivers and streams. Together, these two ecosystems are examples of freshwater ecosystems. Lentic systems are diverse, ranging from a small, temporary rainwater pool a few inches deep to Lake Baikal, which has a maximum depth of 1642 m. [2]