Top-predators can suppress mesopredator behaviour through risk effects. However, there is limited understanding of whether such behavioural suppression can dampen the lethal and sub-lethal effects of mesopredators on bottom level prey. Here, we document a field experiment that examines whether the presence of top-predator cues (visual and chemical stimuli from a coral trout) can cascade to indirectly influence the behaviour and survival of juvenile fish prey of different species (Pomacentrus amboinensis and P. chrysurus) and size (small = 1.18 cm SL vs large = 1.32 cm SL). Results showed that habitat patches exposed to top-predator cues received fewer visits and foraging attacks from mesopredators, leading to higher space use (~46%), feeding rate (~95%), and survival (~67%) from juvenile fish prey. Survival was always higher for individuals of P. amboinensis and of large-size, independent of the presence or absence of top-predator cues. Our data indicate that predation risk from the top-predator indirectly favoured the persistence and behaviour of juvenile fishes by promoting risk-averse behavioural responses in mesopredators. This study underscores the behavioural ­­­­­­mechanisms­ by which risk effects can cascade through the food web and highlights the consequences that harvesting top-predators may have on the replenishment of bottom prey populations.

See detailed methods at: Palacios & McCormick 2020. Positive indirect effects of top-predators on the survival and behaviour of juvenile fishes. Oikos https://doi.org/10.1111/oik.07731

In this study, the effect of a top-predator on the survival and behaviour of juvenile prey was assessed in situ by assigning three experimental treatments to habitat patches and monitoring the fate of four juvenile fishes for up to 72 h. The three treatments comprised: a) top-predator cues, b) a control PVC pipe and c) an empty control. Additional data was collected on the density of mesopredator fish and their behaviour towards the experimental treatments.

More methodological details are available in the paper: https://doi.org/10.1111/oik.07731

EXCEL FILE STRUCTURE

The excel file includes 4 tabs with the following datasets:

1. Juvenile fish survival
2. Juvenile fish behaviour
3. Mesopredator density
4. Mesopredator behaviour

Legend and description of the variables is available on the "ReadMe" file and on each excel tab.