Summary 2

The taxonomic order Oscillatoriales includes many cyanobacteria species, all of which have coin-like or cylindrical cells joined end-to-end to form simple, unbranched filaments. Oscillatoriales are common in freshwater phytoplankton assemblages and some of the species can form dense blooms. Many of the species look very similar, making it difficult to separate the genera in this group of cyanobacteria. The most common genera associated with toxic blooms include Lyngbya (including species moved to Limnoraphis), Oscillatoria, Phormidium, Planktothrix, and Tychonema.

Description 3

All Oscillatoriales have cells that are joined together end-to-end to form long, unbranched filaments consisting of cylindrical, coin-like, or barrel-shaped cells. All the cells in the filament may be nearly identical or the filament may be slightly tapered (usually at one end). The final cell in the filament may be similar to all other cells or may have distinctive features (hook-shaped, tapered, knobbed, bent, vacuolated, etc.).

Members of the Oscillatoriales do not form nitrogen-fixing heterocytes (=heterocysts) or thick-walled akinetes (resting cells). See Dolichospermum for examples of heterocytes and akinetes.

Lyngbya (including species moved to Limnoraphis) and Oscillatoria have short, wide, coin-like cells (2-8 μm in length; up to 25 μm in width; for comparison, a strand of spider silk is about 5 μm wide).

  • Lyngbya (and Limnoraphis ) filaments are surrounded by a firm mucilage sheath. But the trichome (cells without the associated sheath) often creeps out of the sheath, especially when the cells are stressed (e.g., under a hot microscope light!).
  • When the Lyngbya trichome abandons its sheath, it resembles Oscillatoria, which does not form a sheath around the trichome.

Phormidium, Planktothrix, and Tychonema cells are cylindrical or barrel-shaped, but usually not coin-like. Most species have cell lengths that are approximately equal to or greater than the cell width (3-15 μm in width).

  • Planktothrix, Tychonema, and most species of Phormidium do not have a mucilage sheath surrounding the trichome.
  • A few species of Phormidium may develop a mucilage sheath, usually in response to specific environmental conditions.

Ecology 3

The order Oscillatoriales contains many different species of cyanobacteria; only a few are associated with planktonic cyanobacteria blooms.

Planktothrix and some species of Oscillatoria can form gas vesicles in their cells. The vesicles provide a mechanism to move up and down in the water column, so these species are more likely to be planktonic.

  • Species of Oscillatoria that form gas vesicles are being reassigned to different genera. For example, Oscillatoria agardhii (a toxin-forming species) was renamed Planktothrix agardhii and Oscillatoria redekei (another toxin-forming species) was renamed Pseudanabaena redekei.

Tychonema and many species of Phormidium lack the ability to form gas vesicles, but are nevertheless common in plankton samples.

Oscillatoria and Phormidium often form benthic mats on the surface of lake sediments or other submerged substrates.

  • The species found in benthic mats are often (not always) different than the species encountered in plankton samples. But filaments from benthic mats can be suspended in the water column by turbulence.
  • In the spring, rapid photosynthesis can cause oxygen bubbles to become trapped in the algal mat, causing it to float to the water surface.

Oscilatoriales blooms may contain other types of Cyanobacteria, but it is not uncommon for planktonic blooms to be dominated by a single species.

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.

The Oscillatoriales are so diverse that blooms may develop under very different conditions.

  • Limnoraphis birgei (formerly Lyngbya birgei) and Planktothrix isothrix form blooms 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).
  • Planktothrix rubescens usually form toxic blooms in lakes with low or moderate nutrient concentrations (oligotrophic and mesotrophic). (Planktothrix rubescens is most common source of cyanotoxins oligotrophic to mesotrophic lakes in Europe.)

Toxin-producing members of the Oscillatoriales have been found to release microcystins (liver toxins), cylindrospermopsin (liver toxin), anatoxins (nerve toxins), saxitoxin (nerve toxin - paralytic shellfish toxin group), lipopolysaccharides (skin irritants), and BMAA (beta-Methylamino-L-alanine; nerve toxin). Some taxa also release aplysiatoxins/lyngbyatoxin (skin irritants/carcinogens).

  • 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.
  • 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 Microcystis, 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.
  • There is not much information about environmental degradation of cylindrospermopsin, saxitoxins, or aplysiatoxins/lyngbyatoxin.

Similar Genera 3

  • Cyanobacteria: Arthrospira and Spirulina, Geitlerinema, Microcoleus, Pseudanabaena
  • Unbranched Filamentous Algae (examples): Spirogyra (green algae), Ulothrix (green algae), Aulacoseria (diatom)
  • Other: Iron bacteria

Information Sources 3

  • 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, ww.ljlmpress.com.
  • 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. http://www.algaebase.org; searched on 15 March 2018.
  • 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. http://cedar.wwu.edu/cedarbooks/6 (also see: http://www.wwu.edu/iws/).
  • 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.
  • Salmaso, N., L. Cerasina, A. Boscaini, and C. Capelli. 2016. Planktic Tychonema (Cyanobacteria) in the large lakes south of the alps: phylogenic assessment toxigenic potential. FEMS Microbiology Ecology 92:1-14.
  • Vareli, K., E. Briasoulis, G. Pilidis, and I. Sainis. 2009. Molecular confirmation of Planktothrix rubescens as the cause of intense, microcystin-synthesizing cyanobacterial bloom in Lake Ziros, Greece. Harmful Algae 8:447-453.
  • Walsby, A. E. 1994. Gas vesicles. Microbiological Reviews 58:94-144

Synonyms 3

The Oscillatoriales group has been revised extensively, and many of the toxin-forming taxa can be found under numerous identities, depending on the taxonomic source. Due to the diversity in this group, it is not feasible to list all the taxonomy revisions, but here are a few examples:

  • Limnoraphis birgei (formerly Lyngbya birgei)
  • Microcoleus autumnalis (formerly Phormidium autumnale)
  • Microseira wollei (formerly Lyngbya wollei)
  • Planktothrix agardhii (formerlyl Oscillatoria agardhii)
  • Planktothrix isothrix (formerly Oscillatoria agardhii var. isothrix)
  • Pseudanabaena redekei (formerly Oscillatoria redekei)
  • Tychonema bourrellyi (formerly Oscillatoria bourrellyii)

About 4

This guide was prepared by Dr. Robin Matthews, former Director of the Institute for Watershed Studies (http://www.wwu.edu/iws/) 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 http://www.wwu.edu/iws/) and an online key to the cyanobacteria (http://www.snoringcat.net/cyanobacteria_key/index.html).

Sources and Credits

  1. (c) rmatth, some rights reserved (CC BY-NC-SA), uploaded by rmatth
  2. Adapted by rmatth from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Oscillatoriales
  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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