Figure 6 - Mean change in optical density additional to the mean changes observed in the controls for each of the three algal treatments (treatment optical density - mean control optical density). Nannochloropsis sp. (N3600, n=13, mean=0.195±0.040nm), T-Iso sp. (I1800, n=14, mean=0.217±0.038nm) and Thalassiosira sp. (Tw1200, n=13, mean=0.032±0.006nm). Error bars display ±1 standard error. The change in between treatments was significantly different (ANOVA: F_2,40=9.743, P<0.001). Thalassiosira sp. was significantly different from the other two treatments (Tukey HSD; P<0.005), but there was no significant difference in the change in the optical density between T-Iso sp. and Nannochloropsis sp..