The zone that has the most biomass is the photic zone, also known as the euphotic zone, which is the upper layer of the ocean where sunlight penetrates. This zone is typically found at depths up to around 200 meters and supports a high concentration of primary production.
Within this zone, the majority of the biomass is made up of phytoplankton. These tiny, photosynthetic organisms play a crucial role in the marine ecosystem, serving as the foundation of the oceanic food web. Phytoplankton use sunlight, carbon dioxide, and nutrients to produce organic material through photosynthesis, which not only supports a vast range of marine life but also contributes significantly to the Earth’s oxygen supply.
In summary, the photic zone is abundant in biomass primarily due to phytoplankton, which are essential for sustaining both aquatic and terrestrial ecosystems.