Knowra Algae Algae Algae are a diverse, informal group of mostly aquatic organisms that photosynthesize and lack the complex tissues of land plants. They include organisms from single-celled microalgae to large seaweeds.
Phytoplankton : Microscopic photosynthetic organisms that drift in aquatic environments, including algae and cyanobacteria. Many unicellular algae live as drifting phytoplankton in oceans and lakes.
Carbon fixation : The incorporation of inorganic carbon, usually carbon dioxide, into organic molecules. Algae fix dissolved carbon dioxide into biomass, supporting aquatic ecosystems and carbon cycling.
Archaeplastida : A eukaryotic supergroup that includes red algae, green algae, and land plants. Several familiar algal groups share ancestry within this photosynthetic lineage.
Aquaculture : The farming of aquatic organisms, including fish, shellfish, and algae. Seaweed and microalgae are cultivated directly as crops and as aquaculture inputs.
Biological carbon pump : The transport of carbon from surface waters to the ocean interior through sinking organic matter. Algal production supplies much of the organic material that carries carbon into deep water.
Seaweed : Macroscopic marine algae, including species of green, red, and brown algae. Seaweeds are the large, visible forms of algae, not a single evolutionary lineage.
Nitrogen fixation : The conversion of atmospheric nitrogen gas into biologically usable nitrogen compounds. Some algal symbionts and cyanobacteria supply fixed nitrogen in nutrient-poor waters.
Red algae : A major lineage of mostly marine algae with photosynthetic pigments that include phycoerythrin. Red algae are a deeply branching algal lineage with distinctive pigments and ecology.
Agar : A gel-forming substance extracted mainly from red algae and used in food and laboratories. Red algal cell walls provide agar for culture media and food products.
Marine food web : The network of feeding relationships among organisms in marine ecosystems. Algae and algal plankton form the base of many marine food webs.
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