Summary 2

Cylindrospermopsis is a cyanobacteria genus that is occasionally found in freshwater phytoplankton assemblages. In warm, nutrient-rich lakes it can form dense blooms. The most common bloom-forming species, Cylindrospermopsis raciborskii, was originally considered to be a tropical species, but has been expanding its range to include temperate lakes, and has been reported from numerous locations in the US, often in association with toxic blooms.

Description 3

Individual Cylindrospermopsis raciborskii cells are cylindrical or barrel-shaped, longer than wide, and tiny (width = 2-4 μm, which is less than the width of a strand of spider silk). Under magnification the cells appear pale bluegreen or yellowish. The cells sometimes contain gas vesicles, which can result in a mottled coloration. The cells are joined together end-to-end to form short, unbranched, solitary filaments. The filaments can be straight or regularly coiled, and may be tapered or blunt at the ends. This filament variation makes it difficult to identify this species.

In addition to ordinary (vegetative) cells, the filaments may contain conical heterocytes (also called heterocysts) and large, bean-shaped akinetes. Heterocytes are specialized cells that convert dissolved nitrogen gas into ammonium that can be used for cell growth. The heterocytes are located at one or both ends of the filament. Akinetes are resting cells that are resistant to cold temperatures and other unfavorable environmental conditions, and can overwinter in lake sediments. The akinetes may be solitary or form short chains, and are located adjacent (or close) to heterocytes.

Ecology 3

Cylindrospermopsis raciborskii blooms often form during warm, calm weather in lakes and ponds with relatively high nutrient concentrations (nitrogen or phosphorus) or low nitrogen to phosphorus ratios (N:P<15).

  • Recent work suggests that high total phosphorus (TP) or total nitrogen (TN) concentrations are better predictors of bloom formation than N:P ratios.

Cylindrospermopsis raciborskii is tolerant of low light conditions, so blooms are less likely to be limited by shading than other types of cyanobacteria.

The gas vesicles in Cylindrospermopsis cells provide a mechanism to move up and down in the water column, which increases access to nutrients and other growth factors.

Because Cylindrospermopsis is capable of converting dissolved nitrogen gas ammonium, it can dominate blooms when inorganic nitrogen (ammonium, nitrate, and nitrite) is limiting to other types of algae.

  • Nitrogen fixation requires a large amount of energy, so the relationship between nitrogen concentrations and Dolichospermum blooms is complicated; blooms can develop under both low and high inorganic nitrogen concentrations.

Toxicity 3

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.

Cylindrospermopsis cells may produce anatoxins (nerve toxin), cylindrospermopsin (liver toxin), saxitoxins (nerve toxin - paralytic shellfish toxin group), microcystins (liver 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 persis in the aquatic environment for a few weeks.
  • Microcystins are rapidly degraded by naturally occurring but specialized bacteria.
  • If the specialized bacteria are not present, microcystins can persist in the aquatic environment for months.
  • BMAA can bioaccumulate in zooplankton and fish, so this nerve toxin can contribute to health risks long after the toxic bloom has died back.
  • There is not much information about environmental degradation of cylindrospermopsin and saxitoxins, but both types of toxins can persist for weeks in the aquatic environment.

Higher water temperatures and light appear to be associated with increased toxin production.

Not all Cylindrospermopsis blooms result in the release of toxins.

Similar Genera 3

Information Sources 3

  • Antunes, J. T., P. N. Leão, and V. M. Vasconcelos. 2015. Cylindrospermopsis raciborskii: a review of the distribution, phylogengraphy, and ecophysiology of a global invasive species. Frontiers in Microbiology 6:1-13.
  • 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.
  • 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.
  • 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.
  • 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.
  • Gury, M. D. and G. M. Guiry. 2017. AlgaeBase. world-wide electronic publication, National University of Ireland, Galway.; searched on 10 November 2017.
  • Jones, W. W. and S. Sauter. 2005. Distribution and abundance of Cylindrospermopsis raciborskii in Indiana lakes and reservoirs. School of Public and Environmental Affairs, Indiana University, Bloomington, IN, April 2005.
  • 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 3

  • Cylindrospermopsis racibordkii is synonymous with Anabaenopsis raciborskii
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About 4

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 (

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

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