Fig. 1
Micronuclei frequencies [%] in rainbow trout exposed up- and downstream of different WWTPs. Frequencies are given relative to respective control levels. Latter were set to 100%. Bold lines within boxes display the median values, boxes the 25–75% quantiles, whiskers the minimum and maximum values, circles potential outliers. Sample sizes: a WWTP A: upstream: n = 19 and downstream: n = 17; b WWTP B: upstream: n = 18 and downstream: n = 16; c WWTP C: prior to WWTP upgrade: upstream: n = 10 and downstream: n = 10, subsequent to WWTP upgrade: upstream: n = 26 and downstream: n = 31. Asterisks and horizontal lines indicate significant differences between exposure sites, asterisks within boxes indicate significant differences to the respective controls. a WWTP A: ANOVA, F(2,46) = 9.20, p = 0.0004; Tukey HSD: upstream vs. control: p = 0.0086; downstream vs. control: p = 0.0003. b WWTP B: ANOVA(sqrt), F(2,51) = 15.18, p < 0.0001; Tukey HSD: upstream vs. control: p = 0.0002; downstream vs. control: p < 0.0001. c WWTP C: prior to upgrade: Kruskal(sqrt), Chi2(2) = 9.61, p = 0.0080, α′ = 0.0125/upstream vs. downstream: pairwise comparison, p = 0.0200, α′ = 0.0167 and downstream vs. control: pairwise comparison, p = 0.0013, α’ = 0.0100. Downstream/prior vs. subsequent to WWTP upgrade: Kruskal, Chi2(1) = 6.49, p = 0.0109, α′ = 0.0250