Energy is transferred along food chains from one trophic level to the next. However, the amount of available energy decreases from one trophic level to the next.
In a food chain only around 10 per cent of the energy is passed on to the next trophic level. The rest of the energy passes out of the food chain in a number of ways:
Less energy is transferred at each level of the food chain so the biomass gets smaller. As a result, there are usually fewer than five trophic levels in food chains.
The percentage efficiency of energy transfer between trophic levels can be calculated using the equation:
Work out the percentage efficiency of energy transfer between producers and primary consumers in the example.
Calculate the total energy that came into the level of the food chain.
4500 kJ + 500 kJ = 5000 kJ
Identify how much energy is transferred to the next level.
Calculate the efficiency of this transfer using the equation.
energy transferred to next level ÷ total energy in × 100
500 kJ ÷ 5000 kJ × 100 = 10%