Effect of varying light exposure on the cell growth of Licmophora abbreviata

Abstract

Licmophora abbreviata are a light-sensitive organism that serve as oxygen providers for fish, including salmon, in marine ecosystems. For this reason, L. abbreviata growth can directly impact salmon abundance in a specific stream. The purpose of this experiment is to study which light conditions provide optimal growth for L. abbreviata with all other conditions being constant. Three treatments were set up as light, dark, and control conditions each with three samples containing 1.0 x 10^4 cells/mL of L. abbreviata. Our null hypothesis suggested that all three conditions would exhibit the same level of cell growth and our prediction was that we would reject the null hypothesis. All three treatments were placed in incubators with the light treatment receiving 21 hours of light per day, the control receiving 8 hours of light per day, and the dark treatment receiving no light. Samples were taken five, seven, eight, nine and thirteen days following inoculation and counted using a hemocytometer. Our results indicated the greatest overall cell growth occurred in the light condition, and with a p-value of 0.0004, these results can be considered statistically significant. We were able to reject our null hypothesis; thus, our prediction of finding higher cell growth under more light exposure was correct.