| Summary: | Prymnesium parvum, or golden alga, is a euryhaline and eurysaline mixotrophic haptophyte. This alga occurs in all continents except Antarctica, and appeared in the United States in 1985 in the Pecos River in Texas. Prymnesium parvum produces toxins known as prymnesins which have killed millions of fish worldwide in the past few decades. To understand golden alga bloom dynamics, it is imperative to analyze the factors which control its growth. One of the key growth limiting nutrients for P. parvum is phosphorus. Due to its mixotrophic nature, P. parvum is able to obtain phosphorus from both its environment and by grazing on surrounding bacteria and algae. This gives P. parvum a competitive advantage over other algal species in nutrient-limited environments. The first part of this study focused on the effect of abiotic factors on golden alga growth and phosphate uptake. Prymnesium parvum cultures were grown in F/2 media with different salt, nitrate, phosphate and photoperiod conditions. Growth was measured every three days with a spectrophotometer at 680 nm for a total of 30 days. Prymnesium parvum cultures grown in similar conditions were centrifuged at 6000 rpm (3020 g), and the filtrate was filtered, collected and sent to Xenco Laboratories for total phosphorus level measurements. Prymnesium parvum was able to grow in a wide range of nitrate, phosphate and salt concentrations. In nitrate and phosphate variation experiments, P. parvum had a higher rate of growth at half the recommended media concentrations. In experiments with salt concentration variations, P. parvum had a better rate of growth at twice and thrice the recommended media concentrations. This is to be expected, since P. parvum is known to tolerate wide ranges of salinities. The response of phosphate uptake to the above-mentioned variations was quite different. Maximum total phosphorus uptake was noticed in cultures with recommended nitrate, phosphate and salt media concentrations. As the concentration of these nutrients in F/2 media was increased, ...
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