Figure 4

Stormwater runoff causes detrimental effects on zebrafish lateral line development. (a–c) show data from a storm in June 2014, (d–f) from a June 2015 storm, and (g–i) from a January 2016 storm. All experiments were performed on Brn3c:mGFP fish treated from 4 hpf to 4 dpf. (a–c) Fish treated in stormwater from June 2014 had (a) a significant decrease in hair cell number in five head neuromasts (2-tailed t-test, p = 0.009), (b) no significant difference in hair cell number in the two most terminal neuromasts on the tail (2-tailed t-test, p = 0.1024), and (c) a significant decrease in the number of trunk neuromasts (2-tailed t-test, p = 0.014). (d) Fish exposed to stormwater from June 2015 showed a significant decrease in hair cell number in head neuromasts (one-way ANOVA, F_3,43 = 17.99, p < 0.0001). For this storm, concentrations higher than 25% were lethal to the fish. (e) The same stormwater did not have any significant effect on hair cell number in the two most anterior trunk neuromasts (one-way ANOVA, F_3,43 = 1.688, p = 0.1837). (f) The number of trunk neuromasts was significantly decreased in fish treated with stormwater from June 2015 (one-way ANOVA, F_3,43 = 15.84, p = 0.004). (g-h) Fish exposed to stormwater from January 2016 showed a significant decrease in hair cell number in head neuromasts (g; one-way ANOVA, F_3,27 = 15.29, p < 0.0001), and trunk neuromasts (h; one-way ANOVA, F_3,28 = 5.613, p = 0.0038). (i) There was also a significant decrease in the number of trunk neuromasts in the January 2016 group (one-way ANOVA, F_3,28 = 5.564, p = 0.004). For all groups asterisks denote significant differences from untreated animals, as determined with t-tests (panels a–c) or Bonferroni-corrected posthoc testing (panels d–i) (*p < 0.05, **p < 0.01, ****p < 0.0001). N = 7–13 fish per group treatment, bars are + 1 s.d.