Effects of varying pH on the growth rate of the marine diatom Licmophora abbreviata

Abstract

Growth rates of Licmophora abbreviata were studied under three different treatments at pH 7.0, 8.0, and 9.0 with each treatment consisting of three replicates. Previous studies have indicated that diatoms prefer a pH of 8.1 for optimal growth and therefore, the pH 8.0 treatment was the control for the experiment. The initial concentration of each replicate was 1.55x10^3 cells/mL and was determined through the use of a haemocytometer. After a period of 11 days, the maximum growth rates for each treatment was calculated and found to be 2.18 x 10^4 cells/day for pH 7.0, 1.46x10^4 cells/day for pH 8.0 and 1.13x10^4 cells/day for pH 9.0. Additionally, the diatoms grown in pH 8.0 media resulted in the highest concentration after 11 days with pH 7.0 and pH 9.0 following respectively. An ANOVA one-way test was conducted to determine the statistical significance of the data and came back statistically significant, with a calculated p-value of 0.00079, at a confidence level of 95%. Observations of cell shape between the different treatments found that L. abbreviata was triangular shaped in pH 7.0 and 8.0 but not in pH 9.0.