What is the 10% rule in energy transfer between trophic levels?

The 10% rule in energy transfer between trophic levels states that only about 10% of the energy from one level is passed on to the next.

In more detail, the 10% rule is a principle in ecology that describes the energy flow in food chains and food webs. It is based on the observation that, on average, only about 10% of the total energy consumed by organisms at one trophic level is transferred to the next higher trophic level. This is because the majority of energy is lost during the process of consumption, digestion, and metabolism, primarily as heat.

For example, if a plant (producer) captures 1000 units of energy from the sun, a herbivore (primary consumer) that eats this plant will only receive about 100 units of this energy. Similarly, a carnivore (secondary consumer) that eats the herbivore will only receive about 10 units of energy. This pattern continues up the food chain, resulting in a pyramid-like distribution of energy, with the highest amount of energy at the base (producers) and the lowest at the top (apex predators).

This rule is crucial in understanding the structure and dynamics of ecosystems. It explains why there are usually fewer organisms at higher trophic levels and why the biomass decreases from the base to the top of the food chain. It also highlights the inefficiency of energy transfer between trophic levels, which has implications for human food production and resource use. For instance, it suggests that eating lower on the food chain (e.g., plant-based diets) is more energy-efficient and sustainable than consuming higher trophic levels (e.g., meat-based diets).

However, it's important to note that the 10% rule is a rough estimate and can vary depending on the specific ecosystem and organisms involved. Factors such as the type of food, the efficiency of digestion, and the metabolic rate of the organism can influence the amount of energy transferred. Despite these variations, the 10% rule provides a useful framework for studying energy flow in ecosystems.