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Name derivation:
From the Greek aphanizomenon, that which makes itself invisible
Classification:
Aphanizomenon A.Morren ex Bornet and Flahault 1888; 11 of 38 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013). Order Nostocales; Family Nostocaceae In PhycoKey you can find Aphanizomenon either as a tapered filament (trichome) or as a colony.
Morphology:
Straight, always unbranched, trichomes (filaments without visible sheaths) occuring either as individual trichomes or in aggregations of prallel trichomes forming "rafts" - some of which are several centimeters wide and long.  The primary morphology is trichomes (filaments without sheaths), secondary is colonial as ‘rafts’ with many parallel trichomes. Trichomes are tapered at both ends, with end cells usually longer than the central cells. Heterocysts are intercalary (between vegetative cells). Also forms akinetes.
Similar genera:
The 16S rRNA gene sequences of Anabaena and non-toxic Aphanizomenon strains were found to be 99.9 – 100% similar (Lyra et al. 2001). Similarly, Anabaena and Aphanizomenon strains as identified morphologically are intermixed both in morphology and several gene sequences. According to 16S rRNA gene sequences, the heterocystous cyanobacteria form a monophyletic group (Rajaniemi et al. 2005). The two genera are considered synonymous (Gugger et al. 2002).
Toxins produced:
A bloom that occurred in a small farm pond (Durham, NH USA) and Kezar Lake, North Sutton NH USA produced toxins identical in behavior to neosaxitoxin and saxitoxin, respectively, when compared with elution profiles of the paralytic shellfish poisons from Gonyaulax tamarensis var. excavate. (Ikawa et al. 1982). More recently the toxin cylindrospermopsin was found in A. ovalisporum from Lake Kinneret, Israel in 1994 (Banker et al. 1997). Despite the genetic capacity to produce lethal neurotoxins, “superfoods” containing Aphanizomenon flos-aquae were packaged and sold mainly as a “food supplement.” The USA Food and Drug Administration investigated one company (K. C. Laboratories of Klamath Falls, OR USA) that harvested cyanobacterial blooms from Upper Klamath Lake, OR USA. The investigation continued from 1983 – 1986, when the company was forced to discontinue the several products containing cyanobacteria (Ballantine 1986). Evidence for allelopathy, potentially to suppress nutrient or light competition, was found with cell-free extracts from Aphanizomenon flos-aquae (as well as from Nodularia spumigena and Anagaena lemmermannii) against Rhodomonas sp. from the Baltic Sea (Suikkanen at al. 2004).
Immunostimulatory activity:
Large polysaccharides such as ‘Immunion’ extracted from Aphanizomenon flos-aquae stimulate circulation of lymphocytes and monocytes (Jensen et al. 2000) thus enhancing the immune system.
Inhibition of Daphnia:
Aphanizomenon flos-aquae known to contain neosaxitoxin (90% of toxins) and saxitoxin (10%) were incubated in culture and collected from lakewater (Clement’s Pond, Hopkinton NH USA) containing a winter bloom of the same taxon. Filtrate from both sources, as well as addition of pure cause an immediate but reversible decrease in thoracic feeding appendage beat rate of 30 – 50% and a reversible increase in post-abdominal claw ‘kick rate’ (to eject undesirable food particles). Exposure of D carinata to purified saxitoxin has similar effects (Haney et al. 1995).
Habitat:
Freshwater lake plankton. Can form winter as well as summer blooms.
References:
Ballantine, C. 1986. FDA Consumer (July-August issue) reprint is online. Banker, R., S. Carmeli, O. Hadas, B. Teltsch, R. Porat and A. Sukenik 1997. Identification of cylindrospermopsin in Aphanizomenon ovalisporum (Cyanophyceae) isolated from Lake Kinneret, Israel. Journal of Phycology 33:613-616. Gugger, M., C. Lyra, P. Henriksen, A. Couté, J-F Humbert and K. Sivonen 2002. Phylogenetic comparison of the cyanobacterial genera Anabaena and Aphanizomenon. International Journal of Systematic and Evolutionary Microbiology 5:1867-1880. Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 04 September 2013. Haney, J.F., J.J. Sasner and M. Ikawa 1995. Effects of products released by Aphanizomenon flos-aquae and purified saxitoxin on the movements of Daphnia carinate feeding appendages. Limnology and Oceanography 40(2):262-272. Ikawa, Miyoshi, K. Wegener, T.L. Foxall, and J.J. Sasner Jr. 1982. Comparison of the toxins of the blue-green alga Aphanizomenon flos-aquae with the Gonyaulax toxins. Toxicon 20:747-752. Jensen, G.S., D.I. Ginsberg, P. Huerta, M. Citton and C. Drapeau 2000. Consumption of Aphanizomenon flos-aquae has rapid effects on the circulation and function of immune cells in humans. Journal of the American Nutraceutical Association 2(#):. Lyra, C., S. Suomalainen, M. Gugger, C. Vezie, P Sundman, L. Paulin and K Sivonen 2001. Molecular characterization of planktic cyanobacteria of Anabaena, Aphanizomenon, Microcystis and Planktothrix genera. International Journal of Systematic and Evolutionary Microbiology 51:513-526. Rajaniemi, P., P. Hrouzek, K. Kaštovská, R. Willame, A. Rantala, L. Hoffmann, J. Komárek and K. Sivonen. 2005. Phylogenetic and morphological evaluation of the genera Anabaena, Aphanizomenon, Trichormus and Nostoc (Nostocales, Cyanobacteria). International Journal of Systematic and Evolutionary Microbiology 55:11-26. Suikkanen, S., G.O. Fistarol and E. Granéli 2004. Journal of Experimental Marine Biology and Ecology 308(1):85-101. Wood, S.A., Rasmussen, J.P., Holland, P.T., Campbell, R. & Crowe, A.L.M. (2007). First report of the cyanotoxin Anatoxin-A from Aphanizomenon issatschenkoi (Cyanobacteria). Journal of Phycology 43(2): 356-365
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