Energy is transferred along food chains, however, the amount of available energy decreases from one trophic level to the next. The reason for this is that only around 10 per cent of the energy is passed on to the next trophic level. The 10% Rule means that when energy is passed in an ecosystem from one trophic level to the next, only ten per cent of the energy will be passed on. A trophic level is the position of an organism in a food chain or energy pyramid. As we move up an energy pyramid or a trophic level, we can see that less and less of the original energy from the sun is available so that we roughly 10% of energy will be available for the next energy level.