In the oxygen cycle the role of phytoplankton is to?

In the oxygen cycle, phytoplankton play a crucial role by conducting photosynthesis, which converts carbon dioxide and sunlight into oxygen and organic matter. They are responsible for producing a significant portion of the Earth's oxygen, estimated to be around 50% of the total atmospheric oxygen. Additionally, phytoplankton serve as the foundation of aquatic food webs, supporting marine life and contributing to the overall health of ocean ecosystems. Their presence is vital for maintaining the balance of oxygen in the atmosphere.