What does phytoplankton decompose?

Phytoplankton decompose primarily organic matter, including dead phytoplankton cells, other microorganisms, and organic materials from the surrounding environment. This decomposition process is facilitated by bacteria and other microorganisms, which break down the organic material, releasing nutrients back into the water. These nutrients are essential for the growth of new phytoplankton and other aquatic organisms, contributing to the overall health of marine ecosystems. Additionally, the decomposition of phytoplankton plays a crucial role in the carbon cycle, as it helps regulate carbon dioxide levels in the ocean.