The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes such as heat.
In an ecosystem, energy flows from one trophic level to the next through a process known as the food chain. A trophic level refers to a group of organisms that share a common feeding behavior in an ecosystem.
At the base of the food chain are primary producers, such as plants, algae, and some bacteria. These organisms are able to use sunlight and nutrients to produce their own food through the process of photosynthesis.
Primary consumers, such as herbivores, feed on primary producers, and secondary consumers, such as carnivores, feed on primary consumers. This process continues up the food chain, with each trophic level feeding on the one below it.
As energy moves from one trophic level to the next, a significant portion of it is lost. It is estimated that as little as 10 percent of the energy at any trophic level is transferred to the next level, while the rest is lost through various metabolic processes, such as respiration and the production of heat.
This loss of energy at each trophic level is known as the 10 percent rule, and it is one of the key factors that limit the size and complexity of ecosystems. It means that, as energy moves up the food chain, there is less and less available to support the growth and reproduction of organisms at higher trophic levels.
This is why there are typically fewer organisms at higher trophic levels in an ecosystem. It is also why ecosystems are more productive and diverse at lower trophic levels, where there is a greater abundance of energy available to support the growth and reproduction of organisms.