PCB 4043 Chapter Notes - Chapter 21: Allochthon, Detritivore, Food Quality
15 Jun 2016
School
Department
Course
Professor
Document Summary
21. 1: trophic levels describe the feeding positions of groups of organisms in ecosystems. All organisms are either consumed by other organisms or enter the pool of dead organic matter (detritus). In terrestrial ecosystems, only a small portion of the biomass is consumed, and most of the energy flow passes through the detritus. Dead organisms and feces are consumed by organisms called detritivores (primarily bacteria and fungi), in a process called decomposition: detritus is considered part of the first trophic level, and detritivores are part of the second level. Much of the detritus in streams, lakes, and estuaries is derived from terrestrial organic matter: these external energy inputs are called allochthonous inputs, energy produced by autotrophs within the system is autochthonous energy. 21. 2: the amount of energy transferred from one trophic level to the next depends on food quality and consumer abundance and physiology.
