Energy Flow in an Ecosystem
Energy flows one way through an ecosystem.
Trophic level are levels of consumption:
Not all trophic levels may be present.
- 1st trophic level = primary producers.
- 2nd trophic level = primary consumers.
- 3rd trophic level = secondary consumers.
- 4th trophic level = tertiary consumers.
- 5th trophic level = detritivores.
- Biomass - total weight of all living organisms in an ecosystem.
- Biomagnification - tendency of toxins to accumulate in higher trophic levels.
- Food chain - simple, linear series of producers and consumers.
- Food web - complex diagram with branching lines showing the trophic relationships of organisms in an ecosystem.
Autotrophs - the producers
- photosynthesis - plants, approx 1% efficiency.
- chemosynthesis - deep-sea vent H2S bacteria.
Heterotrophs - the consumers
(nourishment from others)
- herbivores - feed on plants, converting about 10% of the consumed energy into biomass.
- carnivore - consume other animals (includes parasites), also about 10% conversion efficiency.
- detritivore - consume refuse of ecosystem (includes decomposers, saprophyte and scavengers).
- omnivore - feeds at many trophic levels.
- filter feeders - filter food from liquid medium.
An Organism's Production Efficiency
- Production efficiency = growth + reproduction
- Energy intake = growth + reproduction - maintenance
Efficiencies vary depending on :
- the organism must maintain a constant body temperature
- if it consumes difficult to digest plant material