Temporal and spatial activity-associated energy partitioning in free-swimming sea snakes

Partitioning energy between critical basal functions and activity-associated behaviours is a primary determinant of animal survival. Consequently, habitat selection is likely to be driven by the efficiency with which resources can be acquired from a heterogeneous energy landscape. Determining how energy partitioning is achieved across temporal and spatial scales is particularly challenging in aquatic animals due to the logistical limitations in estimating field metabolic rates (FMR) while simultaneously examining habitat choice. Here, acoustic telemetry using accelerometers alongside bimodal respirometry were used to correlate vectorial dynamic body acceleration (VeDBA) with oxygen consumption rates ((Formula presented.)) of sea snakes (Hydrophis curtus and Hydrophis elegans) across an ecologically relevant temperature range. Subsequently, VeDBA of free-roaming snakes was used to estimate activity-associated FMR within a near-shore environment over diel, seasonal and spatial scales. Diel changes in activity explained short-term patterns in FMR, whereas seasonal changes in water temperature drove long-term patterns. Spatial analyses demonstrated that activity-associated FMR was elevated in productive seagrass and mudflat habitats, indicative of a concentration of foraging efforts. Our findings illustrate for the first time how sea snakes partition activity-associated FMR across time and space, providing an approach by which we can monitor the impacts of, and vulnerabilities to, natural and anthropogenic disturbances like warming and trawl fisheries. A lay summary is available for this article.