Abstract

Disturbance cues are metabolic byproducts that are argued to function as ‘early warning signals’ where both the senders and receivers can benefit from their release. These disturbance cues are used by many aquatic prey to warn conspecifics of potential local threats and provide prey with valuable information that can help increase their probability of survival following a predatory encounter. Due to their identity as metabolic byproducts, it is shown that sender diet quality influences the information conveyed to a receiver. However, only one disturbance cue study has exposed fish to ecologically relevant, natural flowing water conditions. Thus, we assessed the influence of varying ambient current flow by conditioning sender guppies in current treatment buckets for 3 days with artificially increased current flow velocities and exposed receiver guppies to the collected disturbance cues and undisturbed odours. We found no effect of the cue received and the current experienced by senders. This suggests that disturbance cues are not affected by ambient current which suggests that the cues can continue to function when streams are altered. Since responses to disturbance cue are known to be influenced by background risk, we conducted a second experiment, where background risk was manipulated. We found that high background risk fish decreased their activity significantly when exposed to disturbance cues across all current flow ranges. Interestingly, the odours of undisturbed conspecifics may function as ‘social foraging cues’ for high background risk receivers who may be more willing to forage when they perceive safety. However, neither the the current experienced by senders, nor the cue received influenced responses in low background risk fish. Overall, our results show that while the current velocity the sender experiences and their resulting levels of physical activity do not influence the responses of receiver fish, fish exposed to higher background risk appeared to be more sensitive to chemical information from conspecifics.