Algae and phytoplankton are microscopic aquatic plants that are the basis of the food web in the aquatic environment. Algae are generally larger than phytoplankton and often form visible blooms on the water’s surface. Algae are found in both fresh and saltwater environments and can range from simple single-celled organisms to complex multicellular forms. Phytoplankton are the smallest and most abundant of the aquatic plants and exist in both fresh and saltwater environments. While algae and phytoplankton are both important sources of food for many aquatic organisms, they also play an important role in the cycling of nutrients and energy in aquatic ecosystems.