WHAT IS PHYTOPLANKTON? Phytoplankton is the "grass" of oceans: microscopic plants at the foundation of the food chain. Like land-based plants, phytoplankton require sunlight, water and nutrients to grow. That's why it is mostly found at or near the surface of the ocean. There are many different species, each with a distinctive shape. But they all get their green color from chlorophyll, the pigment they use during photosynthesis. Photosynthesis is the process by which plants convert carbon dioxide into oxygen and carbohydrates to make their own food. This involves a complicated series of chemical reactions, fueled by sunlight. First, the light energy converts water into an oxygen molecule, a positively charged hydrogen ion, and a free electron. Then the light, carbon dioxide, and broken down water are combined to make a sugar molecule. Each of these reactions takes place in a reaction center -- a kind of chemical factory for producing energy. Because phytoplankton relies on carbon dioxide for photosynthesis, the larger the world's population of phytoplankton, the more carbon dioxide gets pulled from the atmosphere, and the more oxygen is released.
The American Geophysical Union contributed to the information contained in the TV portion of this report.