Three Causes of Energy Loss Between Trophic Levels
1. Incomplete Consumption
- Not all organisms or parts of organisms are consumed by the next trophic level.
- The energy in uneaten material is passed to decomposers, not higher trophic levels.
- Locusts may eat parts of plants but rarely consume them entirely.
- Similarly, predators often leave behind bones or hair.
2. Incomplete Digestion
- Not all consumed food is digested or absorbed.
- This waste becomes energy for decomposers, bypassing the food chain.
Animals cannot digest tough materials like cellulose or keratin, and undigested food is egested as waste.
3. Energy Loss in Cell Respiration
- Carbohydrates, proteins, and other food molecules are oxidized during cell respiration to release energy.
- This energy powers vital processes like movement and active transport, with most released as heat.
- Only the carbon compounds not used in respiration pass to the next trophic level.
Understanding Energy Flow Through Ecosystems
- Energy transformations are inefficient.
- Studies estimate that only 10% of the energy at one trophic level is passed to the next, with 90% lost due to the factors above.
- This explains why:
- Producers form the broad base of the energy pyramid.
- Higher trophic levels, like carnivores, are fewer in number and biomass.
The Role of Decomposers and Detritus Feeders
- Decomposers and detritus feeders recycle energy from dead matter and waste:
- Decomposers: Bacteria and fungi break down organic matter, returning nutrients to the soil.
- Detritus Feeders: Organisms like earthworms consume detritus, aiding decomposition.
These organisms are vital for ecosystem sustainability, even though they don’t directly transfer energy to higher trophic levels.
Self review- Why does only 10% of energy transfer to the next trophic level?
- How do decomposers contribute to the efficiency of energy cycling?
- What might happen to an ecosystem if decomposers were absent?
