How is the pyramid of a biomass in oceans inverted? Does it not go against the basic law of conservation of mass?

Biomass is the amount of living organic matter. Pyramid of biomass is graphical representation of biomass sequence wise per unit area of different trophic levels. Pyramid of biomass is inverted because in aquatic ecosystem producers are phytoplankton that has a short life span and turn over and have lower mass than zooplankton. The biomass of a trophic level is dependent on the longevity of members.

• Food chain in ocean – {Phytoplankton → zooplankton → predatory fish.}