Trait-mediated foraging drives patterns of selective predation by native and invasive coral-reef fishes

As the geographic ranges of species are increasingly altered by forces such as biological invasion and climate change, when and where will strong biotic interactions arise within reassembling communities? Prey selectivity data are often of limited use for predicting future consumptive interactions because they are specific to the identity and relative abundance of species in past assemblages. Here, we investigate whether the strength of consumptive interactions can be predicted based on a priori knowledge of behavioral traits that are hypothesized to affect the predation process and recur across species. To test this approach, we conducted multi-species foraging trials with coral-reef fishes in the Bahamas, a diverse, trait-rich fauna for which interactions are likely shifting rapidly due to the introduction of predatory Indo-Pacific lionfish. We evaluated predictions about the combined effects of three behavioral traits—water column position of both predator and prey, anti-predator aggregation behavior of prey, and hunting strategy of predators—on successive phases of the predation process and ultimately the strength of predator–prey interactions. Tracking predator and prey behaviors revealed that inter-specific variation in traits mediated relative encounter, attack, and capture rates between different predators and prey. Behaviorally driven bottlenecks at different stages of the process underpinned selective consumption by each predator species, resulting in large differences in total mortality rates among prey species. Our analysis also suggests that unique behaviors exhibited by invasive lionfish, rather than naïve responses by prey, mediate their high foraging success relative to native predators. Our results illustrate how incorporating a priori knowledge about foraging and anti-predator traits can improve predictions of the strength of emergent consumptive interactions caused by global change. © 2019 The Authors