in a food pyramid, there is typically low biomass at the top (I.e., there are very few individual tertiary consumers, whereas, there are numerous individual producers). Explain this phenomenon, citing evidence relating to energy flow and how energy support the ecosystem
The phenomenon of low biomass at the top of a food pyramid can be explained by the principles of energy flow and how energy sustains an ecosystem.
The energy flow in an ecosystem follows the trophic levels, which represent different feeding positions or levels in a food chain or pyramid. At the base of the pyramid are the primary producers, such as plants, algae, and some bacteria, which convert sunlight into chemical energy through photosynthesis. These producers have the highest biomass as they can produce their own food and energy.
Moving up the pyramid, the primary consumers (herbivores) consume the primary producers. Energy from the ingested biomass is used for their own metabolism and growth, but a significant portion is lost as heat and waste products. This loss of energy limits the amount of energy available to the next trophic level.
As the energy flows up the pyramid, from primary consumers to secondary consumers (carnivores that eat herbivores), and further up to tertiary consumers (carnivores that eat other carnivores), the available energy decreases. This decrease occurs due to the inefficiency of energy transfer between trophic levels, as each level cannot convert and assimilate all the energy from the organisms they consume.
The efficiency of energy transfer between trophic levels is estimated to be around 10%. Meaning, only about 10% of the energy from one trophic level is passed on to the next. The majority of the energy is lost as heat, used for respiration, or expended in various metabolic processes. This energy loss limits the amount of biomass that can be sustained at higher trophic levels, leading to low numbers of tertiary consumers compared to the primary producers.
Evidence supporting this phenomenon can be observed in natural ecosystems. For example, in a grassland ecosystem, there may be abundant grass and other primary producers. This supports a larger number of primary consumers like rabbits or grasshoppers, which in turn can sustain some secondary consumers like snakes or hawks. However, there will be far fewer tertiary consumers, such as apex predators like lions or wolves, due to the limited energy available at the top of the pyramid.
In summary, the low biomass at the top of a food pyramid is a result of energy loss and limited energy transfer efficiency as one moves up the trophic levels. This phenomenon is supported by evidence of more individual primary producers at the base of the pyramid compared to higher trophic levels.