Student Project Figures Figure 13 Figure 13: Average optical density (absorption), using a wavelength of 550nm, for three different treatments including algae, microbeads and a mix of both algae and microbeads, in artificial seawater (± standard error (SE)). Treatment significantly effected the optical density measurements (ANOVA, n=3/treatment: F 1, 2 = 482.8, P = 1.845e-7). Figure 13