Inter- vs intra-individual variation and temporal repeatability of escape responses in the coral reef fish Amblyglyphidodon curacao

Abstract

Fast-start escape responses are critical behaviours used by fishes during predator-prey encounters and some interactions with hetero- and conspecifics. In experimental studies, escape responses are often measured once per individual and considered representative of maximum performance. However, few studies have compared variability and repeatability in escape performances within and among individuals. Using the tropical damselfish Amblyglyphidodon curacao, we quantified inter- and intra-individual variation in behavioural and kinematic components of escape performance during repeated presentations of a stimulus at 15 min intervals. Individual maximum escape performance was repeatable through time, but there was considerable variation in the magnitude of responses both among and within fish. We found no evidence of habituation or fatigue due to repeated stimulations, suggesting that fish can be stimulated multiple times to ensure that an accurate estimate of maximum escape performance is obtained.

Keywords: C-start; Damselfish; Fast-start; Habituation; Kinematics; Locomotion; Mauthner cells; Swimming.

Fig. 1.

The staghorn damsel (Amblyglyphidodon curacao; left) commonly uses fast-starts to escape from cheating cleaner fish (Labroides dimidiatus; bottom). Instead of removing ectoparasites, cleaner fish occasionally bite their clients to feed on mucus and scales. Photo credit: Simon Gingins.

Fig. 2.

Inter- and intra-individual variation in measures of escape performance. Coefficient of variation (CV) for measures of escape performance for each A. curacao across five stimulus presentations (empty blue circles): (A) response latency (n=14) and (B) escape distance (D_esc), (C) maximum velocity (U_max), (D) maximum acceleration (A_max) and (E) turning rate (n=12). Filled blue circles represent the mean CV within individuals; error bars are 95% confidence intervals. Filled red circles represent the CV among individuals.

Fig. 3.

Relationships between the highest and second highest escape performance measures in A. curacao across five stimulus presentations at 15 min intervals. (A) response latency (n=14) and (B) escape distance (D_esc), (C) maximum velocity (U_max), (D) maximum acceleration (A_max) and (E) turning rate (n=12).

Fig. 4.

Effect of repeated stimulations on measures of escape performance. (A) Response latency (log transformed), (B) escape distance (D_esc), (C) maximum velocity (U_max), (D) maximum acceleration (A_max) and (E) turning rate by trial number (n=5) for A. curacao stimulated every 15 min. The left panels (box-and-whisker plots) show the raw data; whiskers extend to the highest value within 1.5 times the inter-quartile range; data beyond the end of the whiskers are outliers and indicated as blue points. The right panels show the mean and 95% confidence intervals for each trial computed using a linear mixed-effects model (LMM; accounts for repeated measures on the same individuals through time) and visualized with the R package effects (Fox et al., 2014).