algal bloom




Examples of Microcystis

microcystis (image 1)

400X total magnification; 10 μm scale bar.

microcystis (image 2)

400X total magnification; 10 μm scale bar.

microcystis (image 3)

400X total magnification; 10 μm scale bar.

microcystis (image 5)

400X total magnification; 25 μm scale bar.


Microscopic to macroscopic colonies; spherical, oval, lobate (having multiple lobes), elongate, or irregular in shape; sometimes composed of packet-like sub-colonies (Microcystis viridis is a good example of this); sometimes clathrate (lattice-like or net-like; with distinct holes between elongated bands of cells; Microcystis aeruginosa colonies at certain stages of development, for example). Cells irregularly arranged, either sparsely or densely. Colonial mucilage is fine and colorless; sometimes forming a wide border around cells; margins may be either diffuse or distinct; mucilage with a refractive outline in some species (for example, Microcystis wesenbergii). Cells spherical, or hemispherical following cell division; 0.8-6(9.4) μm diameter; without their own individual envelopes; aerotopes present. Cell content is pale blue-green, but the presence of aerotopes causes the cells to look brown.


Free-floating in plankton; common bloom-former in eutrophic waterbodies.


  • Johansen, J. R., & Komárek, J. (2015). Coccoid Cyanobacteria. In J. D. Wehr, R. G. Sheath, & J. P. Kociolek (Eds.), Freshwater Algae of North America: Ecology and Classification (2nd ed., pp. 103-104). Waltham, MA: Elsevier.
  • Komárek, J. & Anagnostidis, K. (2008). Cyanoprokaryota-1. Teil/Part 1: Chroococcales. In H. Ettl, G. Gärtner, H. Heynig, & D. Mollenhauer (Eds.), Süßwasserflora von Mitteleuropa (Vol. 19/1, pp. 225-232). Heidelberg, Germany: Spektrum.