Summary: | Alarm substances, released by injured prey, and odours from predators, such as northern pike, are chemical cues associated with increased predation risk in aquatic ecosystems. In laboratory studies, individual prey can respond to the presence of such cues by reducing conspicuous behaviours, such as foraging and by seeking shelter. These responses may reduce growth and reproduction, which could have effects at the population-level. The objective of my study was to determine if alarm substances or pike odour have population-level effects on fathead minnow. In the cattle trough experiment, alarm substances and pike odour had no effect on breeding behaviour and recruitment of young; however, spawning occurred earlier with exposure to alarm substances relative to water controls. In a larger-scale pond experiment, alarm substances had no effect on reproduction or recruitment. Despite individual-level effects in the laboratory, exposure to alarm substances and pike odour had no impact at the population scale. === Ecology
|