Why algae in the ocean can have a very high npp and a very low amount of stored biomass

The algae in the ocean have a very high Net Primary Productivity (NPP) and a very low amount of store biomass. This is because THE GROWTH RATE OF ALGAE IN THE OCEAN IS HIGH. The store biomass is low because THE PRIMARY CONSUMERS FEED ON THESE ALGAE THUS LOWERING THE BIOMASS AMOUNT. The production of biomass is related to the NPP.