Algal Symbioses


Algae (including cyanobacteria) enter into symbioses with protists, animals, fungi and plants. They contribute to the nutrition of their partners through photosynthetic carbon fixation and, for cyanobacteria, nitrogen fixation.

Keywords: photosynthesis; nitrogen fixation; cyanobacteria; dinoflagellate; coral; lichen

Figure 1.

Photosynthetic algae, Symbiodinium sp., in sea anemone Anemonia viridis. The algal cells are coccoid, with permanently condensed chromosomes in the nucleus (n) and a peripheral plastid (p). Bar, 3 Tm. Transmission electron micrographs: A. E. Douglas.

Figure 2.

Nitrogen‐fixing cyanobacteria in plants. (a) Filaments of the cyanobacteria in a cavity of the water fern Azolla. Bar, 10 Tm. (b) Intracellular cells of the cyanobacteria in the glad cells of Gunner magallenica. Bar, 5 Tm. Scanning electron micrographs of R. Honegger, reproduced from Douglas ().

Figure 3.

The stratified lichen thallus of Parmelia borreri. (a) Vertical section through thallus, showing the algal symbionts (s) sandwiched between two symbiont‐free layers, the dorsal cortex (c) and ventral medulla (m). Bar, 10 Tm. (b) Morphology of the contact between the fungus and algal symbiont, Trebouxia. Each symbiont cell is in contact with a single fungal projection (arrow). Bar, 1 Tm. Scanning electron micrographs of R. Honegger, reproduced from Douglas ().



Allemand D, Furla P and Benazet‐Tambutte S (1998) Mechanisms of carbon acquisition for endosymbiont photosynthesis in Anthozoa. Canadian Journal of Botany 76: 925–941.

Carpenter EJ, Montoya JP, Burns J et al. (1999) Extensive bloom of a N‐2‐fixing diatom/cyanobacterial association in the tropical Atlantic Ocean. Marine Ecology Progress Series 185: 273–283.

Douglas AE (1994) Symbiotic Interactions. Oxford: Oxford University Press.

Fagoonee I, Wilson HB, Hassell MP and Turner JR (1999) The dynamics of zooxanthellae populations: a long‐term study in the field. Science 283: 843–845.

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Further Reading

Ahmadjian V (1993) The Lichen Symbiosis. New York: Wiley.

Bergman B, Matveyev A and Rasmussen U (1996) Chemical signalling in cyanobacterial‐plant symbioses. Trends in Plant Sciences 1: 191–197.

Douglas AE (1995) Ecology of symbiotic micro‐organisms. Advances in Ecological Research 26: 69–103.

Muscatine L (1990) The role of symbiotic algae in carbon and energy flux in reef corals. In: Dubinsky Z (ed.) Ecosystems of the World: Coral Reefs, pp. 75–87. Amsterdam: Elsevier.

Nash TH (1995) Lichen Biology. Cambridge: Cambridge University Press.

Peters GA (1991) Azollaand other plant–cyanobacterial symbioses: aspects of form and function. Plant and Soil 137: 25–36.

Trench RK (1998) Diversity of symbiotic dinoflagellates and the evolution of microalgal–invertebrate symbioses. In: Lessios HA and Macintyre IG (eds) Proceedings of the 8th International Coral Reef Symposium, pp. 1275–1286. Balboa, Republic of Panama: Smithsonian Tropical Research Institute.

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How to Cite close
Douglas, Angela E(Apr 2001) Algal Symbioses. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0000327]