Summary 4

Nodularia is a cyanobacteria genus that is usually found in warm, brackish or saline lakes and estuaries. In brackish desert lakes it can form dense blooms. Some species of Nodularia are associated with benthic environments, but the most common toxin-forming species, Nodularia spumigena, is planktonic.

Description 4

Individual Nodularia spumigena cells are oval, compressed (width > length), and tiny (width = 8-16 μm; for comparison, a strand of spider silk is about 5 μm wide). Under magnification, Nodularia spumigena cells are bright blue-green, and appear granular or mottled due to gas vesicles in the cells. The cells are joined together end-to-end to form long, unbranched filaments that are surrounded by clear, often transparent, sticky mucilage. Individual filaments may be straight or slightly bent, but can also be aggregated into tangled clumps.

In addition to ordinary (vegetative) cells, the filaments may contain pale blue or orange heterocytes (also called heterocysts) and large, granular, thick-walled akinetes. 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, and can overwinter in lake sediments.

Ecology 4

Nodularia spumigena blooms often form during warm, calm weather in saline or brackish lakes, ponds, and estuaries with relatively high nutrient concentrations (nitrogen or phosphorus) or low nitrogen to phosphorus ratios (N:P<15). Although the genus is usually associated with marine and estuarine environments, Nodularia spumigena blooms are common in some warm desert lakes (e.g., Great Salt Lake, Utah and Pyramid Lake, Nevada).

  • The gas vesicles in Nodularia spumigena cells provide a mechanism to move up and down in the water column, which increases access to nutrients and other growth factors.
  • Because Nodularia spumigena 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 Nodularia spumigena blooms is complicated; blooms can develop under both low and high inorganic nitrogen concentrations.

    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.

    Nodularia spumigena cells may produce nodularin (liver toxin) and BMAA (beta-Methylamino-L-alanine; nerve toxin).

    • Nodularin is similar in structure to microcystin. Microcystins are rapidly degraded by naturally occurring but specialized bacteria, and some of the bacteria can also degrade nodularin.
    • BMAA can bioaccumulate in zooplankton and fish, so this nerve toxin can contribute to health risks long after the toxic bloom has died back.

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

    Not all Nodularia spumigena 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.
    • 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.
    • Gury, M. D. and G. M. Guiry. 2019. AlgaeBase. world-wide electronic publication, National University of Ireland, Galway.; searched on 10 April 2019.
    • Kormas, K. and D. Lymperopoulou. 2013. Cyanobacteria toxin degrading bacteria: Who are they? BioMedican Research International Vol. 2013, Article 463894.
    • 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

    Nodularia spumigena has no commonly used synonyms.

    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 (

    Sources and Credits

    1. (c) rmatth, some rights reserved (CC BY-NC-SA), uploaded by rmatth
    2. (c) rmatth, some rights reserved (CC BY), uploaded by rmatth
    3. (c) Bryan Milstead, some rights reserved (CC BY-NC-SA), uploaded by Bryan Milstead
    4. (c) rmatth, some rights reserved (CC BY-NC-SA)

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