Summary 3

Cylindrospermum is a genus of filamentous cyanobacteria that is occasionally found in freshwater phytoplankton assemblages, but is not usually associated with toxic planktonic blooms. Cylindrospermum is more commonly associated with benthic environments, where it can form dense, slimy mats on damp soils or mixed in with shoreline vegetation of lakes and ponds.

Description 4

Cylindrospermum cells are cylindrical or barrel-shaped, tiny (3-7 μm wide; for comparison, a strand of spider silk is about 5 μm wide), and slightly longer than wide. Under magnification the cells are blue-green or gray-green, and may appear granular. The cells are joined together end-to-end to form long, unbranched, untapered, straight or gently curved filaments. The filaments are surrounded by clear, often transparent mucilage, and may slimy form mats on submerged vegetation or other surfaces.

In addition to ordinary (vegetative) cells, one or both ends of the filament may contain pale blue heterocytes (=heterocysts). The filaments may also have one (occasionally two) large, blue-green or brown akinetes adjacent to the heterocytes. Heterocytes are specialized cells that convert dissolved nitrogen gas into ammonium that can be used for cell growth. Akinetes are resting cells that are resistant to cold temperatures and other unfavorable environmental conditions. Akinetes are usually produced near the end of the growing cycle, and can overwinter in lake sediments.

Ecology 4

Cylindrospermum is not a usually found in planktonic cyanobacteria blooms.

  • Cylindrospermum cells lack gas vesicles, which are common in bloom-forming planktonic taxa like Dolichospermum and Microcystis

Cylindrospermum is usually found in shallow water associated with shoreline vegetation in nutrient-poor lakes and ponds, especially water that is slightly acidic, boggy, or peaty.

Cylindrospermum is capable of fixing dissolved nitrogen gas, which helps provide nitrogen in boggy sites where inorganic nitrogen (ammonium, nitrate, and nitrite) is limiting to other types of algae.

Toxicity 4

Identifying which cyanobacteria species are producing toxins is more difficult that it sounds. Historically, cyanobacteria taxa were described as "potentially" toxic based on whether they were collected in a toxic bloom. With the advancement of culturing techniques and genetic analysis, toxicity information is becoming more exact. But this is an ongoing process, so the toxicity information on these pages should be considered a work in progress.

Cylindrospermum cells may produce anatoxins (nerve toxin), lipopolysaccharides (skin irritants), and BMAA (beta-Methylamino-L-alanine; nerve toxin). These toxins are released into the ambient environment when the cell wall is disrupted (cell lysis).

  • Anatoxins are rapidly degraded by sunlight and at pH levels that are slightly above neutral (neutral pH = 7.0). At low pH levels, and in the absence of light, anatoxins may persist in the aquatic environment for a few weeks.
  • There is some evidence that anatoxins can be degraded by specialized bacteria, similar to microcystins, but this process is not well documented.
  • BMAA can bioaccumulate in zooplankton and fish, so this nerve toxin can contribute to health risks long after the toxic bloom has died back.

In some instances, higher water temperatures and light appear to be associated with increased toxin production, but toxic Cylindrospermum blooms have not been well documented.

Not all Cylindrospermum blooms result in the release of toxins.

Similar Genera 4

Information Sources 4

  • Bennett, L. 2017. Algae, cyanobacteria blooms, and climate change. Climate Institute Report, April 2017.
  • Berg, M and M. Sutula. 2015. Factors affecting the growth of cyanobacteria with special emphasis on the Sacramento-Jan Joaquin Delta. Southern California Coastal Water Research Project Technical Report 869.
  • Caldwell Eldridge, S., R. Wood, and K. Echols. 2012. Spatial and temporal dynamics of cyanotoxins and their relation to other water quality variables in Upper Klamath Lake, Oregon, 2007-09. USGS Scientific Investigations Report 2012-5069.
  • D'Anglada, L., J. Donohue, J. Strong, and B. Hawkins. 2015. Health effects support document for the cyanobacterial toxin anatoxin-A. U.S. Environmental Protection Agency, Office of Water, EAP-820R15104, June 2015.
  • Chorus, I. and J. Bartram (Eds). 1999. Toxic cyanobacteria in water: a guide to their public health consequences, monitoring and management. The World Health Organization E & FN Spon, London.
  • EPA. 2014. Cyanobacteria and Cyanotoxins: Information for Drinking Water Systems. U. S. Environmental Protection Agency, Office of Water, EPA-810F11001.
  • Graham, L. E., J. M. Graham, L. W. Wilcox, and M. E. Cook. 2016. Algae, Third Ed., ver 3.3.1 . LJLM Press,
  • Granéli, E. and J. T. Turner (Eds.) 2006. Ecology of Harmful Algae. Ecological Studies, Vol. 189, Springer.
  • Lage, S., H. Annadotter, U. Rasmussen, and S. Rydberg. 2015. Biotransfer of B-N-Methlamino-L-alanine (BMAA) in a eutrophicated freshwater lake. Marine Drugs 13:1185-1201.
  • Matthews, Robin A., "Freshwater Algae in Northwest Washington, Volume I, Cyanobacteria" (2016). A Collection of Open Access Books and Monographs. 6. (also see:
  • Meriluoto, J., L. Spoof, and G. Codd. 2017. Handbook of Cyanobacterial Monitoring and Cyanotoxin Analysis. John Wiley & Sons, Chichester, UK.
  • Paerl, H. W. 2014. Mitigating harmful cyanobacterial blooms in a human- and climatically-impacted world. Life 2014 4:988-1012.
  • Walsby, A. E. 1994. Gas vesicles. Microbiological Reviews 58:94-144

Synonyms 4

Cylindrospermum has no commonly used synonyms.

About 5

This guide was prepared by Dr. Robin Matthews, former Director of the Institute for Watershed Studies ( and professor emeritus at Western Washington University. In addition to this guide she has also written two ebooks (more on the way) on phytoplankton identification (see the "algae books" link on and an online key to the cyanobacteria (

Sources and Credits

  1. (c) rmatth, some rights reserved (CC BY-NC-SA), uploaded by rmatth
  2. (c) Rich Fadness, some rights reserved (CC BY-NC), uploaded by Rich Fadness
  3. Adapted by rmatth from a work by (c) Wikipedia, some rights reserved (CC BY-SA),
  4. (c) rmatth, some rights reserved (CC BY-NC-SA)
  5. Adapted by rmatth from a work by (c) Bryan Milstead, some rights reserved (CC BY-NC-SA)

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