Fig 1.
Schematic diagram of the timeline for treatment conditioning and experimental design.
On the 15th day in complexity treatments all juvenile P. chrysurus were trained to associate predator odours (C. boenak) as a threat with chemical alarm cues (CAC). After acclimation in circular arena, either saltwater, herbivore (A. nigrofuscus) or predator odour was introduced for 5 minutes. Most fish were startled by a stimulus to induce fast-start escape response, which were recorded from below, while a subset of saltwater and predator samples were collected for cortisol analysis. See S1 Fig for more details on experimental tank.
Fig 2.
Effect of complexity and forewarning odours on escape response and kinematic of Pomacentrus chrysurus.
Boxplots show the median and 25% quantiles, black dots are outliers, grey dots are raw data points for response latency (A,B), response speed (C,D), maximum speed (E,F), maximum acceleration (H,I), and response distance (J,K). Letters above bars represent LSD groupings of means. Sample sizes for complexity trials were n = 44, 48, and 51 (low, medium, high), and for predator odour trials n = 54, 44, and 45 (control, herbivore, predator), respectively.
Table 1.
Results of two-way ANCOVA’s on the fast-start response variables for Pomacentrus chrysurus.
Fig 3.
Effect of complexity and forewarning odours on cortisol concentrations of juvenile Pomacentrus chrysurus.
Boxplots show the median and 25% quantiles, black dots are outliers, grey dots are raw data points and letters above bars represent Tukey’s HSD groupings of means. Sample sizes for control odours were n = 10, 9, and 9 (low, medium, high) and for predator odours n = 12, 11, and 11 (low, medium, high), respectively.
Table 2.
Results of two-way ANOVA on cortisol concentrations of juvenile Pomacentrus chrysurus.