Why is it important for phytoplankton to stay in the photic zone?

Phytoplankton must remain in the photic zone because this upper layer of water is where sunlight penetrates, enabling photosynthesis. By harnessing sunlight, phytoplankton produce oxygen and serve as the primary producers in aquatic food webs, forming the base for marine and freshwater ecosystems. Staying in this zone ensures they can efficiently convert light energy into chemical energy, supporting both their growth and the organisms that depend on them for food.