Photosynthetic plankton, including microalgae, blue-green bacteria, and some true bacteria. These organisms are produced in surface waters of aquatic ecosystems, to depths where light is able to penetrate. Sunlight is necessary since, like terrestrial plants, phytoplankton use solar radiation to convert carbon dioxide and water into organic molecules such as glucose. Phytoplankton form the base of nearly all aquatic food chain/webs, directly or indirectly supplying the energy needed by most aquatic protozoans and animals. Temperature, nutrient levels, light intensity, and consumers (grazers) are among the factors that influence phytoplankton community structure.