Jacob W. Brownscombe
Department of Biology, Carleton University, Ottawa, ON K1S 5B6, CANADA.
Energy is the currency of life, by which we can measure how ecological and anthropogenic factors influence individual fitness, scaling up to population and ecosystem dynamics. Energy is expended and gained by organisms through diverse behavioural tactics aimed at maximizing fitness. My overarching hypothesis for this dissertation is that ecological and anthropogenic factors influence animal behaviour and energetics. I tested this hypothesis in two coastal marine fish species, bonefish (Albula vulpes) and great barracuda (Sphyraena barracuda) using a combination of field studies and controlled experiments. In the wild, landscape features had the greatest impact on bonefish activity and energy expenditure at both fine (i.e., between habitats on a single coral reef crest) and broad (i.e., between coastal habitats and regions) spatial scales. Diel period, water temperature, and tide state also influenced bonefish behaviour and energetics, with some consistent patterns across environments, including greater activity and energy expenditure during the day, as well as ebbing and low tides. Bonefish activity levels and habitat selection also corresponded with temperature-related physiological performance. Comparing two disparate coastal ecogeographic regions, activity- and temperature-based estimates of bonefish energy expenditure were higher in the fringing coral reefs of tropical Culebra, Puerto Rico than the expansive sand flats of sub-tropical Eleuthera, The Bahamas; however, home ranges were significantly larger in Eleuthera than Culebra, which likely has significant energetic costs that may contribute to differences in growth rates between the regions. From a more applied perspective, a common anthropogenic stressor, recreational angling, caused significant locomotory (i.e., swimming capabilities) and behavioural (i.e., refuge use) impairment in bonefish and great barracuda, which resulted in increased post-release predation risk. Retaining bonefish for a short period prior to release reduced this impairment and may be a useful strategy for improving post-release survival in environments with high predator burden. Collectively, by examining how ecological and anthropogenic factors influence fish behaviour and energetics, my dissertation has advanced our understanding of fundamental ecology and management of coastal marine fish and their ecosystems.