Golden Algae, The Hidden Fish Killer

Key Environmental Requirements

• Macêdo et al. 2023 found that more than 1900 μS/cm conductivity encouraged the rapid growth of P. parvum. P. parvum temperature tolerance is between 5 and 30⁰C, with optimal growth around 15-26⁰C. Lysing of the cell wall occurred when temperatures rose above 34⁰C, and when temperatures fell below 10⁰C growth was severely limited (Larsen et al. 1998).
• P. parvum can obtain nutrients from both photosynthesis and by consuming prey (mixotrophy). Brooks et al. (2011) have described, “Individual cells can aggregate in ‘‘feeding swarms,’’ where they encircle and consume a prey organism already debilitated by toxins. Such predatory behavior tends to occur late in a bloom cycle as a strategy to obtain nutrients under depleted conditions (Brooks et al. 2011).” This is a competitive and aggressive species that is fit for survival in nutrient-depleted habitats, making management difficult.
• As light intensity increased, P. parvum increased its phosphate uptake speed from the environment, suggesting light intensity may also profoundly affect competition. However, there seems to be a balancing mechanism with respect to light intensity since excessive light intensity actually causes growth inhibition. Rahat and Jahn (1965) were the first to describe P. Parvum as having heterotrophic growth in the dark, but they noted that growth only occurred if high concentrations of glycerol were available. Once energy reserves were depleted, growth was slowed substantially, suggesting photosynthesis is the preferred metabolic pathway for bloom formation.