The Effect of Lowered pH on the Rate of Phagocytosis in Tetrahymena thermophila

  • Ariene Cabantog
  • Ian Chok
  • Harmeet Gill
  • Quinn H. Stewart


With global warming acidifying oceanic and freshwater environments, the effects of pH have a significant impact on aquatic organisms (Heino et al., 2009). Salmon, a keystone species, rely heavily on ciliated protozoans as a food source (Orias et al., 2011; Pauly et al. 1996). The purpose of this experiment was to test the effects of pH on phagocytosis rate of Tetrahymena thermophila. This was done by exposing cells to ink-stained, pH-adjusted media and counting the number of ink-stained phagocytized vacuoles in five cells from three replicates of each treatment condition every 10 minutes during a two-hour feeding period. The mean rates determined were: 0.057 vpm at pH 5, 0.074 vpm at pH 6, and 0.074 vpm at pH 7. Using a one-way ANOVA, we obtained a test statistic (F) of 0.073 (Df =2) and a pvalue of 0.930 suggesting that the mean rate of phagocytosis does not differ between pH treatments (pH 5, pH 6, pH 7). Based on these results, we do not have sufficient evidence to support our alternative hypothesis that pH does have an effect on the rate of phagocytosis of T. thermophila.