Diatoms, Dinoflagellates, Blue Green Algae

Appearance: Most individual structures are microscopic and appear

                      collectively as brownish, cloudy substances in the water

Habitat: Throughout the water column

Seasonal Appearance: All year, with blooms in the spring and fall

Sensitivity to Human Action








Distinguishing Features & Behaviors

            Phytoplankton are single-celled, free-floating, nonswimming plants. Phytoplankton are the foundation of all life in Narragansett Bay, serving both directly and indirectly as food sources for all living animals. Zooplankton, which consists of small animals and larval forms of invertebrates and fish, together with phytoplankton make up the group called plankton.

            The predominant forms of phytoplankton are diatoms, golden brown algae, green algae, blue green algae and dinoflagellates. Over 20,000 species of diatoms alone exist in the world. The have an exoskeleton composed of silica and have no means of locomotion. Their movement through the water is dependent solely on currents.

            Blue green algae is the dominant freshwater phytoplankton, while diatoms make up the majority of phytoplankton in water of higher salinity. Phytoplankton use the process of photosynthesis to sustain themselves, converting carbon dioxide into oxygen and organic materials. Phytoplankton are believed to produce 80% of the organic material in the world. Phytoplankton are consumed by a wide range of small and large fish and invertebrates in the Bay.

 Relationship to People

            Phytoplankton form the basis of life in the world’s oceans. By converting sunlight and inorganic elements into plant tissue, these tiny cells begin the complex food web that ultimately sustains all marine fish, invertebrates, mammals and birds. Phytoplankton determine the color, odor and taste of saltwater and is a fundamental measure of productivity in the marine environment.