The pyramid representing the land ecosystem is traditional with producers being greater in mass than primary

Question

Shown below are 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.

Answer 1

(a) Phytoplankton 

Producers will still have the highest amount of energy captured from sunlight which will continue to reduce as we move towards the top of the pyramid.

(b) Since the total mass in the lower trophic level is lesser there will be lesser food available to higher trophic levels causing organisms to die sooner than usual.