Effects of Salinity on the Population Growth of C. reinhardtii

Abstract

Chlamydomonas reinhardtii’s growth is affected by a variety of abiotic factors,including salinity. Salinity is an important abiotic stressor that can inhibit productivity and growth. This experiment aimed to test the effects of salinity on C. reinhardtii’s growth. Effects of salinity on C. reinhardtii are important to study as they are a vital source of nutrition for salmon, a keystone species with major influences on the animal kingdom. The null hypothesis was that greater salinity will result in no difference in cell growth rate of C. reinhardtii. The alternate hypothesis was that changes in salinity concentrations will result in differences in cell growth rate of C. reinhardtii. It was predicted that the 0 mM NaCl sample will have the highest rate of cell growth, and lowest growth rate would be observed at 150 mM NaCl. Samples of C. reinhardtii were grown in 0mM, 50mM, 100mM, and 150mM NaCl concentrations, and were counted over a period of 13 days. Mean rate of cell growth of the C. reinhardtii within the four salinity concentrations were determined. Numerical values of salinity concentrations were converted to categorical factors using R. These values were inputted into a one-way ANOVA test, followed by a Tukey HSD test to determine whether changes in mean cell growth rate were significant. Based on the Tukey HSD test, all comparisons yielded p-values <0.05, with exception of the 100mM and 150mM NaCl growth rates. Our data showed that the 0mM NaCl sample had the largest growth, while the 150mM sample had the smallest growth. This demonstrates that as salinity increased, the population growth rate of C. reinhardtii decreased. Therefore, we concluded that while C. reinhardtii can grow in saline conditions, growth is significantly restricted by increased salinity.