Shown below are two food pyramids.
The pyramid representing the land ecosystem is traditional with producers being greater in mass than primary consumers and so on. Sometimes, in aquatic ecosystems, an inverted pyramid exists. Here, the total mass of producers (phytoplankton) is much smaller than the top consumers (big fishes).
(a) Which level is likely to have the most amount of energy in such an aquatic ecosystem? Give a reason to support your answer.
(b) Such aquatic ecosystems are not considered to be sustainable. Justify this statement.