please explain why biomass and energy decreases fron one trophic level to the next
Each stage in a food chain containing many organisms can be complicated. But the basic explanation is that: an organism within a food web or chain is a potential source of food for other organisms. Energy flows through these food chains, right through an ecosystem starting with a primary producer right up to the top of a chain to a tertiary consumer. This is usually measured by the amount of energy which is captured by photosynthesis from a primary producer. When the primary producer is consumed by another organism (a primary consumer) The energy which was originally captured through photosynthesis is converted into either biomass or lost to respiration/ waste products. This continues up the food chain to the tertiary consumer. So essentially at each stage the original energy is continuously lost through each stage through these processes.
At each trophic level in an ecosystem, there is a decrease in biomass and energy. This phenomenon is known as the ecological pyramid or the pyramid of energy.
The primary reason for this decrease is due to the inefficiency of energy transfer between trophic levels. Let me explain it further:
1. Energy loss as heat: Organisms at each trophic level require energy for their metabolic processes, such as respiration, movement, and growth. However, some amount of energy is lost as heat during these processes and cannot be transferred to the next trophic level. This heat loss reduces the available energy for the next level.
2. Energy loss through waste: Organisms also excrete waste products, such as feces and urine, which contain organic matter and energy. This energy-rich waste is not consumed by organisms at higher trophic levels, resulting in a loss of energy from the system.
3. Inefficiency of energy conversion: As energy is transferred from one trophic level to another, it is not fully converted or absorbed. Consider a simple food chain: plants (producers) are eaten by herbivores (primary consumers), which are later consumed by secondary consumers (predators). The energy that plants harness from the sun through photosynthesis is only partially converted into biomass (energy stored in the bodies of plants) and is further reduced when herbivores consume the plants. This inefficiency continues with each subsequent trophic level, leading to a gradual decrease in biomass and energy.
Additionally, as one moves up the food chain, the total amount of biomass decreases because energy is lost and expended at each trophic level. Top predators require a larger amount of energy to sustain their higher metabolic rates and drive their hunting and capturing activities. Hence, fewer individuals can be supported at the higher trophic levels due to limited energy availability.
To recap, the decrease in biomass and energy from one trophic level to the next is primarily caused by energy loss as heat, inefficient energy conversion, and the high-energy requirements of top-level predators.