Energy Flow in an Ecosystem

Energy flows one way through an ecosystem.

1. Trophic level are levels of consumption:
   • 1^st trophic level = primary producers.
   • 2^nd trophic level = primary consumers.
   • 3^rd trophic level = secondary consumers.
   • 4^th trophic level = tertiary consumers.
   • 5^th trophic level = detritivores.
   Not all trophic levels may be present.
2. Biomass - total weight of all living organisms in an ecosystem.
3. Biomagnification - tendency of toxins to accumulate in higher trophic levels.
4. Food chain - simple, linear series of producers and consumers.
5. Food web - complex diagram with branching lines showing the trophic relationships of organisms in an ecosystem.

Autotrophs - the producers

(self-nourishing)

1. photosynthesis - plants, approx 1% efficiency.
2. chemosynthesis - deep-sea vent H₂S bacteria.

Heterotrophs - the consumers

(nourishment from others)

1. herbivores - feed on plants, converting about 10% of the consumed energy into biomass.
2. carnivore - consume other animals (includes parasites), also about 10% conversion efficiency.
3. detritivore - consume refuse of ecosystem (includes decomposers, saprophyte and scavengers).
4. omnivore - feeds at many trophic levels.
5. filter feeders - filter food from liquid medium.

An Organism's Production Efficiency

1. Production efficiency = growth + reproduction
2. Energy intake = growth + reproduction - maintenance
3. Efficiencies vary depending on :
   • the organism must maintain a constant body temperature
   • if it consumes difficult to digest plant material