Fig. 4.

Diurnal patterns in cortisol and melatonin levels are associated with the risk-taking behaviour. Full body melatonin (a) and cortisol (b) concentrations (pg g⁻¹ and ng g⁻¹ body weight, respectively) were determined by ELISA in early (EE, red) and late emerging fish (LE, blue) over 24 h during a 14:10 light to dark cycle (indicated by white and grey bars, double plotted). Samples were taken at 1, 7, 13, 15, 19 and 23 h circadian time (hCT). Data shown are means ± SE (N = 3). Letters indicate significant difference (two-way ANOVA, with time and coping style as variables, Bonferroni post hoc test, p < 0.05, N = 6. Data shown are means ± SEM)