Energy Efficiency
Ecological efficiency is the net production of new biomass at each trophic level as a percentage of the total energy flowing through that trophic level.
Generally speaking, this is approximately 10%.
The dry mass of living material (biomass) at each stage in a food chain, is less than it was at the previous stage.
The biomass and the chemical energy contained in the biomass is reduced at each trophic level because:
•not all light energy is utilised to make biomass. Some is reflected or passes straight through the plant
•some materials and energy are always lost in the organism’s waste materials
•respiration supplies all the energy needs for living processes, including movement, growth and temperature regulation– this energy is not available to the next trophic level.
•not all of the individual organisms in a trophic level will get eaten by organisms in the next level up.
•similarly, not all parts of an organism are eaten or digested (cellulose, roots, bones, etc).
Explain why not all of the energy in producer biomass can be converted into energy in primary consumer biomass.
Give two reasons why the percentage of energy transferred between consumers tends to be low.
Explain, in terms of energy, why food chains with the fewest steps are most efficient.