Why are phytoplankton essential to aquatic life zones?

Phytoplankton are essential to aquatic life zones because they serve as the foundational producers in the marine food web, converting sunlight and carbon dioxide into organic matter through photosynthesis. This process not only generates oxygen, vital for the survival of most aquatic organisms, but also supports a diverse range of marine life, from small zooplankton to large fish and marine mammals. Additionally, phytoplankton play a crucial role in regulating the global carbon cycle, influencing climate and ocean health. Their abundance and diversity are key indicators of ecosystem health and productivity.