How do phytoplankton control the carbon cycle?
Besides acting as the first link in the food chain, phytoplankton are a very important part of ocean life. The carbon dioxide in the atmosphere is in balance with carbon dioxide in the ocean. During photosynthesis, phytoplankton remove carbon dioxide from sea water and release oxygen as a by-product. This allows the oceans to absorb additional carbon dioxide from the atmosphere. If fewer phytoplankton existed, atmospheric carbon dioxide would increase. Phytoplankton also affect carbon dioxide levels when they die. Phytoplankton, like plants on land, are composed of substances that contain carbon. Dead phytoplankton can sink to the ocean floor. The carbon in the phytoplankton is soon covered by other material sinking to the ocean bottom. ln this way, the oceans act as a sink, a place to dispose of global carbon, which otherwise would accumulate in the atmosphere as carbon dioxide. Other global sinks include land vegetation and soil. However the carbon in these sinks frequently is return
