Examining the Effects of Light Wavelengths on the Growth Rate of Chlamydomonas reinhardtii

  • Nathan Chua
  • Jal Pranjal
  • Sahba Mozaffarian
  • Justine Law


Chlamydomonas reinhardtii is a unique alga that acts as a major food source for salmon species. It has the unique ability to grow autotrophically in the light, and heterotrophically in the dark. In this study, we aimed to explore the behaviour of C. reinhardtii in different light conditions. Specifically, we examined the growth rate of C. reinhardtii under different light treatments. These light treatments varied in light wavelength, and consisted of white light (positive control), red light (lower visible light frequency), blue light (higher visible light frequency), and green light (intermediate visible light frequency). We used a hemocytometer to do cell counts over a period of 14 days and displayed the growth rate C. reinhardtii on growth curves. We then calculated the overall growth rate, and performed perform a one-way ANOVA test to determine if there is a significant difference in the growth rate between the different light treatment groups. The ANOVA test revealed an F-value of 24.37 and a p-value of less than 0.0001. Since ANOVA found a significant difference between the four treatment groups (p-value < 0.05), we performed a Tukey-Kramer test to determine which treatment groups are significantly different. The multiple comparison test revealed that the growth rates of the control group was significantly different to the growth rate of the red, blue, and green treatment groups (p-values < 0.05), and the growth rates of the red, blue, and green treatment groups were not significantly different from each other (p-values > 0.05).