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Name derivation:

"Ship's Stern" -- Prymnos. [I fail to see the connection...]

Classification:

Prymnesium  Massart  1920;  21 of 24 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013).

Order Prymnesiales;  Family Prymnesiaceae

Recent molecular observations including both nuclear and ribosomal DNA sequences suggest a revision of the prymnesiophyceae including prymnesium species (Edvardsen et al. 2011).

Morphology:

Elipsoid beflagellate unicells 6 – 18 µm long with two chloroplasts and a short haptonema (Throndsen 1997).

Similar genera:

 

Habitat:

Plankton of coastal marine and brackish estuaries and bays.

Phagotrophy:

Intake of particles, especially living cells (phagotrophy), provides a source of nutrition other than, and often in addition to (mixotrophy), photosynthesis.  Prymnesium is a mixotroph, using  both PS and phagotrophy (Tillmann  1998).

 

Toxicity

Prymnesium produces substances called “prymnesins” with a high lytic activity that attacks the membrane of many eucaryotic cells tested such as mammalian erythrocytes, HeLa cells, neurons, normal liver and amnion cells, through damage to the cytoplasmic membrane.  In contrast the toxin is relatively ineffective for tested bacteria such as E. coli, apparently protected by their bacterial wall (Ulitzur and Shilo 1970).  Gill-breathing animals are most susceptible to prymnesins, such as mussels, crayfish, amphibia, and fish (Shilo 1981). Chemically prymnesins are considered to be of polyhydroxy-polyene-polyether nature (Igarashi et al. 1995).

The toxicity of Prymnesium parvum increases in cultures with nutrient (N, P) deficiency, suggesting that the prymnesins serve as allelopathic agents (Granéli and Johansson 2003).

An extensive fish kill of several tons was observed in the brackish Lake Vargsundet, SW Finland in July 1997.  At that time there was a dense population of Prymnesium sp., tentatively P. parvum (1 – 4 x 105 cells ml-1).  Essentially all (10) fish species known to be present in the lake were eliminated from the epilimnion.  Gulls removed many of the dead fish at the surface and shoreline.  Many more dead fish as well as crayfish were seen on the lake sediment by SCUBA divers.  Several invertebrates were also affected (Lindholm et al. 1999).

 Although Planktothrix agardhii, a toxic cyanobacterium, was also present, most of the population was located in a relatively thin layer in the metalimnion (5-6 m) and thought not to be important in the fish kill.  Strong neurotoxic effects were observed in the epilimnetic lakewater, but less so in water from the metalimnetic layer.  Only trace amounts of microcystin-RR were found in the epilimnion.  Warm and calm weather along with high concentrations of phosphorus (TP) and nitrogen (TN), high TN/TP atomic  ratio (>40), and high pH (>9.0) (Ibid 1999).

 

References:

Edvardsen, B., W. Eikrem, J. Throndsen, A.G.  Sáez, I. Probert, and L.K. Medlin  2011.  Ribosomal DNA phylogenies and a morphological revision provide the basis for a revised taxonomy of the Prymnesiales (Haptophyta).  European Journal of Phycology 46(3):202-228.

Granéli, E., and N. Johansson  2003.  Harmful Algae 2: 135-145.

Guiry, M.D. and G.M. Guiry  2013.  AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.  http://www.algaebase.org; searched on 30 April 2013.

Igarashi, T., Y. Yasukatsu, M. Murata & T. Yasumoto, 1995. Chemical studies on prymnesins isolated from Prymnesium parvum. In Lassus P., G. Arzul, E. Erard, P. Gentien & C. Marcaillou(eds), Harmful Marine Algal Blooms. Lavoisier Publishing, Paris: 303–308.

Lindholm, P., K. Kurki-Helasmo, B. Kincaid, and J. Meriluoto  1999.  Toxic algae and fish mortality in a brackish-water lake in Ĺland, SW Finland.

Shilo, M.  1981.  The toxic principles of Prymnesium parvum.  In:  Carmichael, W.W. (ed.), The Water Environment.  Algal Toxins and Health.  Plenum Press, NY.  pp 37-47.

Throndsen, J.  1997.  The planktonic marine flagellates.  In:  Identifying marine phytoplankton.  Tomas, C.R. (Ed.).

Tillmann, U.  1998.  Phagotrophy by a plastidic haptophyte, Prymnesium patelliferum.  Aquatic Microbial Ecol. 14:155-160.

Ulitzur, S., and M. Shilo  1970.  Effect of Prymnesium parvum toxin, cetyltrimethylammonium bromide and sodium dodecyl sulphate on bacteria.  J. Gen. Microbiol. 623: 363-370.