Behavioural scores across 25min observations of Amphiprion crysopterus and Stegastes leucostictus

Despite existing evidence for significant observer effects across several taxa, little is known about the minimum periods of acclimation that should precede behavioural observations. To date, most studies either do not report any acclimation periods or include a nonspecific period without empirically quantifying its appropriateness.

Here we conducted in situ behavioural observations of two species of demersal coral reef fishes using cameras and/or observers to examine the biases associated with either approach. For both treatments, we generated 25 min time series of a number of vigilance-associated behaviours (i.e., distance from shelter and mate, time out of shelter, swimming activity) and estimated the point of acclimation using changepoint analysis.