Question

Some aquatic ecosystems have inverted biomass pyramids, in which primary consumers outweigh the producers. Why is it that a pyramid of biomass, but not a pyramid of net production, may be inverted?

Answer 1

Answer:

Pyramid of biomass measures the amount of living organic matter at any trophic level. It is inverted in some aquatic ecosystems specially the ones present in oceans. For example: [phytoplankton ⇒ zooplankton ⇒ fish] food chain has an inverted pyramid of biomass. Phytoplankton weigh less and have small size compared to zooplankton. They are also consumed very fast so their number is less compared to higher tropic level organisms. Hence this pyramid is inverted. Pyramid of net production is not inverted though because phytoplankton reproduce very fast and have a high turnover rate so their net production remains constant. Net production and energy always decrease as we move from lower to higher trophic level because some amount is lost at each trophic level.