All three metals significantly affected pluteus size (PO/BL ratio; one-way ANOVA,Cu: F(2, 15) = 6.01, p = 0.012, Pb: F(3, 19) = 4.19, p = 0.02, Zn: F(3, 19) = 4.70, p = 0.013).However, LOEC and NOEC could not be calculated for zinc, as none of the treatments were significantly different from the control (Dunnett’s comparison, t = -2.20, p = 0.10), despite being within detectable range (MSD = 1.5% of control mean).LOECs for copper and lead were 5 μg/L Cu and 50 μg/L Pb (Dunnett’s comparison;Cu: t = -2.62, p = 0.035, Pb: t = -2.99, p = 0.02; Figure 2.2) with a MSD of 1.2 and1.3% of the control mean, respectively. Corresponding NOECs were lower for lead(20μg/L) than NOEC based on normal development (50 μg/L), but identical for copper (1 μg/L). Overall, copper and lead induced a slightly shorter PO arm relative to the total body length, but the effect was small. E. chloroticus larvae exposed to 5μg/L Cu had only a marginally lower PO/BL ratio than did the control larvae (mean PO/BL ratio ± standard deviation: 0.57 ± 0.015 vs. 0.60 ± 0.017 in controls). A very similar effect was observed in plutei exposed to 50 μg/L Pb (PO/BL ratio: 0.57 ±0.018 vs. 0.60 ± 0.017 in controls).