Prymnesium parvum

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[edit] Prymnesium parvum

Prymnesium parvum is a haptophyte, beloning to Haptophyta (=Prymnesiophyta). The species is of concern because of it's ability to produce a toxin. It is a flagellated alga that is normally found suspended in the water column. It was first identified in North America in 1985 and it is not known if it was introduced artificially (e.g.,invasive species or possibly missed in previous surveys). Toxin production mainly leads to fish kills and appears to have little effect on cattle or humans. This distinguishes it from red tide, which are algal bloom whose toxins lead to harmful effects in people. Although no harmful effects are known, it is not recommended to consume dead or dying fish exposed to a P. parvum bloom.

[edit] Biology

P. parvum grows grows in a salinity range of 0.1%-10% with an optimum at 0.3-6% although strains collected in different places appear to have different salinity tolerances. The alga produces dimethylsulfoniopropionate (DMSP) and other unknown polyols, likely as an adaptation to osmoregulation. The temperature range which allows survival of P. parvum is between 2 and 30 deg C. Growth as low as pH of 5.8 has been observed, but cells typically prefer higher pH ranges. The organism prefers highly light environments, but growth can be inhibited by excessive light (photoinhibition). The organism is capable of heterotrophic growth in the dark in the presence of glycerol and grazes on bacteria, especially when phosphate is limiting. It has therefore been hypothesized that P. parvum satisfies it's phosphate needs by eating bacteria. P. parvum can use a wide range of nitrogen sources, including ammonium, nitrate, amino acids (which ones apparently depends of pH), creatine, but is unable to use urea. New evidence has shown that the toxins produced by this alga are induced by physiological stresses, such as N and P depletion due to competition with the environment. As a note, this toxin is meant to kill other microscopic organisms, which means that fish kills are an accidental side-effect (P. parvum are not trying to kill the fish).

www.bom.hik.se Removal of Prymnesium parvum (Haptophyceae) cells under different nutrient conditions by clay (pdf)
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Literature Review of the Microalga Prymnesium parvum and its Associated Toxicity

Influence of different nutrient conditions on cell density, chemical composition and toxicity of Prymnesium parvum (Haptophyta) in semi-continuous cultures