Interactions between multi-species marine predator aggregations and the energy landscape.

Multi-species predator aggregations can be found in both coastal and pelagic ecosystems, forming for both foraging and refuging (resting) purposes. The energy landscape represents the power costs required to move through or reside within a habitat. As species may differ in their morphology, buoyancy and length, there may be species-specific heterogeneity in their energy landscapes. Here, we highlight how the energy landscape may influence the small-scale distribution of predators within an aggregation and potentially their ability to forage. We focus on negatively buoyant predators, such as sharks, which can reduce their metabolic costs by swimming in upwelling currents. We develop a biomechanical model to show how shark length and buoyancy alter the energetic benefit sharks obtain from swimming in upwelling currents. We provide evidence of small-scale spatial separation between shark species within a French Polynesian channel, which may be related to species exploiting optimal energetic environments. Second, we show how the energy landscape influences patch residence times in foraging predators and how this may differ between species. For instance, different species within a multi-species foraging aggregation may quit the patch at different prey densities. Overall, the energy landscape may help to drive the distribution of species within aggregations or even inter-species patterns of assortativity. This article is part of the theme issue 'Multi-predator feeding aggregations in the pelagic'.