The amount of biomass in terrestrial ecosystem is small compared to that of the aquatic ecosystem
Terrestrial biomass generally decreases markedly at each higher trophic level. Terrestrial producers are grasses, trees or shrubs. They have a much higher biomass than the animals that consume them. The marine biomass increases at each higher trophic level.
The biomass of consumers is larger than the biomass of primary producers. The primary producers in the ocean are tiny phytoplankton that grow and reproduce rapidly, so a small mass can have a fast rate of primary producers. In terrestrial ecosystem, primary producers grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production.