Which trophic level would have the least energy available?

The trophic level with the least energy available is indeed the tertiary consumers. This is due to the transfer of energy that occurs through the different levels of the food chain. Energy decreases as it moves from one trophic level to the next, primarily due to the second law of thermodynamics, which states that energy transformations are not 100% efficient.

When energy is transferred from producers (plants that convert solar energy into chemical energy through photosynthesis) to primary consumers (herbivores that eat producers), a significant amount of energy is lost as heat through metabolic processes. This same loss occurs again when primary consumers are consumed by secondary consumers (carnivores that eat herbivores) and again when secondary consumers are consumed by tertiary consumers (top predators).

As a result, each successive trophic level has less energy available to support organisms. Therefore, tertiary consumers, being at the top of this energy pyramid, have the least energy available to them when compared to producers and consumers at lower trophic levels. This concept demonstrates the efficiency of energy transfer and highlights the importance of producers in sustaining the entire ecosystem.