What are the characteristics of phytoplankton and what does phytoplanktons do for the environment?

Phytoplankton are microscopic, plant-like organisms that float in aquatic environments. They play a crucial role in the environment by producing oxygen through photosynthesis, serving as the base of the marine food web, and removing carbon dioxide from the atmosphere. Additionally, phytoplankton are key indicators of ecosystem health and can help regulate nutrient cycles in aquatic ecosystems.