A coral reef ecosystem contains algae, small fish, large fish and sharks. A student claims that the shark population can never be as large as the algae population in this ecosystem. Explain why the student's claim is correct, with reference to energy flow through the ecosystem.

Algae are the primary producers in the reef, using light energy to make biomass. When small fish eat the algae, only a fraction of that energy is transferred to the fish; the rest is lost as heat during respiration, movement and maintaining body temperature, and as waste products such as faeces and urine. The same loss occurs when large fish eat the small fish, and again when sharks eat the large fish. Because energy is lost at each trophic level, the amount of energy available to support organisms decreases stepwise. Consequently, the biomass that can be supported at the top trophic level (sharks) is far less than that at the bottom (algae), so the shark population can never be as large as the algae population.