Prymnesium parvum

Prymnesium parvum of Haptophyta is sometimes colloquially misnamed "golden alga" causing confusion with golden alga or Chrysophyceae of Heterokontophyta, leading to contradictions in terms, especially in non-scholarly texts (such as those from state wildlife departments).

Biology

P. parvum grows in a salinity range of 0.5 - 30 psu (Practical Salinity Unit) with an optimum at 15 psu although strains collected in different places appear to have different salinity tolerances. A strain called LB 2797 (isolated from Colorado River in Texas) shows a biphasic growth pattern namely, maximum cell densities increased as salinity increased from 5 to 15 psu but decreased at higher levels in laboratory culture. The alga produces dimethylsulfoniopropionate (DMSP) and other unknown polyols, likely as an adaptation to osmoregulation. The environment must be between 2 °C (36 °F) and 30 °C (86 °F) for P. parvum to live. Growth at a pH of as low as 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 limited. It has therefore been hypothesized that P. parvum satisfies its phosphate needs by consuming bacteria. P. parvum can use a wide range of nitrogen sources, including ammonium, nitrate, amino acids (which ones apparently depends on 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 nitrogen and phosphorus depletion due to competition with the environment.