The devil you know: predator presence changes bonefish personality and social network dynamics (#91)
Using an integrative approach we combined standard observation protocols with biologging, respirometry and recent statistical innovations in social network analysis to ascertain the impact of predation threat on bonefish (Albula vulpes) behaviour and social networks. For our study, we captured a shoal of adult bonefish from a coastal flat and transplanted them to a large, natural and enclosed wetland area for observation. After an acclimation period and determination of social structure, two juvenile lemon sharks (Negaprion brevirostris) were added to the wetland area to examine the effects of potential predators on interaction patterns, habitat use and general activity of the bonefish. Following this second component, sharks were removed, and social network structure was again measured to determine if previously observed network dynamics returned to original patterns. Following observations, all bonefish were placed in respirometers to ascertain individual differences in metabolic rate. All bonefish and sharks were captured simultaneously at a single site to minimize holding effects and insure all individuals had the same experience in terms of capture and previous exposure to sharks. Each bonefish was outfitted with individually identifiable tri-axial accelerometer loggers and allowed to move freely throughout the entire system for a period of 7 days. Using a recently developed Markov chain model, we quantified the network dynamics of the test population, including consistency of individual network positions across observations and compared that to other metrics of behaviour. We found strong correlations between individual network characteristics, movement patterns, metabolic rate and estimates of behavioural type within treatments. However the presence of sharks was disruptive to all aspects of behaviour studied (networks, activity, habitat use). This disruption appeared to have a lasting effect, as the differences in behaviour continued throughout the third treatment following shark removal. Our study is among the first to characterize the nature and impact of predator presence on network attributes as well as integrate network analysis, accelerometry, respirometry and direct behavioural measurements concurrently.