TROPHIC LEVEL

A feeding level in an ecosystem. The four trophic levels are autotrophs (primary producers) plus the three heterotroph groups: herbivores (primary consumers), carnivores (secondary consumers), and top carnivores (tertiary consumers). The ecological efficiency at each level is low, with ~10 per cent of the energy consumed being transferred to chemical energy and the remainder being expended as respiration. This accounts for the small number of trophic levels and can be used as an argument in support of vegetarianism. The complexity of food chains/webs means that assigning organisms to single trophic levels is a simplification of the trophic structure. Detritivores (decomposers) feed off the dead remains of the organism at all trophic levels and are sometimes considered to represent a separate trophic level.

[See alsoautotrophic organism, heterotrophic organism, predator-prey relationships, trophic cascade, trophic-dynamic approach]