Detritivory, trophic shunt and the apparent trophic cascade hypothesis.
Florida International University, Miami, Fl. USA 1
Detritus is a universal component of ecosystems. In a majority of ecosystems, most primary production is uneaten by herbivores and turns into detritus. Many animals feed on detritus and then become food items of predators. These predators also often prey on herbivores. Thus, energy and material may shunt from detrital food chains into the classic herbivore food chain. In many ecosystems, the flow to the upper trophic levels through detritivore channel can be equal or larger than that through the herbivore channel. I constructed a model to examine the features of a food web that contains both herbivore and detritivore food chains and the features of trophic shunt. The model simulated trophic interactions among six groups: edible autotrophs, inedible autotrophs, detritus, herbivores, detritivores, and predators. In such food webs, an apparent trophic cascade may arise, which contains a large standing crop of predators, a disproportionately small standing crop of herbivores, and very abundant primary producers. Some ecosystems may look greener than others even if their primary productivity is more severely limited by nutrients. The aquatic food web of the Everglades marshes appears to show this pattern.
Keywords: food web, apparent trophic cascade, detritivory, herbivory, trophic shunt.
This abstract is being presented at: 4:15 PM in session:
Oral Session #11: Trophic Cascades.