Behavioural flexibility in reef fishes responding to a rapidly changing wave environment
Flexible traits can be crucial in helping animals meet the challenges of a highly variable environment. We examined whether coral reef fishes systematically alter their swimming behaviour in response to temporal changes in hydrodynamic conditions. Exploiting site-based differences in wave energy impinging on reef habitats over calm and rough weather, we found many reef fishes changed their swimming behaviour alongside increases in wave-driven water motion. Most fishes tended to orient their bodies parallel to oncoming wave-driven flow and recruited additional stabilising fins during rough weather; such changes in swimming behaviour aid stability and minimise drag. However, not all species displayed such flexibility, with fishes possessing highly tapered pectoral fins and high levels of swimming performance continuing to successfully navigate reef habitats without significantly altering their swimming behaviour. We highlight how labile behaviours augment the morphology and performance of species to underpin their occupation of habitats subject to variable environmental conditions.
KeywordsReef Fish Coral Reef Fish Swimming Behaviour Exposed Site Maximum Wave Height
Our study was conducted at Jiigurru (Lizard Island), in the country of the Dingaal people. We thank S. Binning, D. Roche, R. Sheb’a, and the staff from Lizard Island Research Station for their assistance during field work. Thanks to D. Roche and S. Binning for statistical advice, and M. Noble for assistance with illustrations and constructive feedback on the manuscript. Funding was provided by the Australian Research Council (CJF), the Australian National University (CJF, SJH), and the Anjeli Nathan Memorial Scholarship (SJH). The study was conducted under Great Barrier Reef Marine Park Authority permit G09/30054.1 and ANU Animal Experimentation Ethics Committee approval F.BTZ.41.10.
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