Wudkevich, K., B.D. Wisenden, D.P. Chivers, and J.F. Smith. 1997. Reactions of Gammarus lacustris to chemical stimuli from natural predators and injured conspecifics. Journal of Chemical Ecology 23:1163-1172.
Amphipods have can detect chemical stimuli from injured conspecifics and potential predators that are active in different habitat types. What is the behavioral response of Gammarus to these different chemical cues?
Many aquatic animals use either alarm pheromones or kairomones to reduce their risk of predation, because water is a great medium for the dispersal of chemical signals. Detection of such a signal indicates to the potential prey that a predator may be in the vicinity, and thus increases prey survival by decreasing the probability they will be in the same habitat.
The activity of Gammarus was recorded in response to several stimuli. In the first experiment, the stimuli included water, pike, and Gammarus. In the second experiment, dragonfly larvae were used in place of pike. In both experiments, Gammarus significantly decreased their time spent active. Time spent in the water column was less with the pike stimulus than with the dragonfly stimulus, however this difference was not significant.
In conclusion, Gammarus have an ability to detect and respond to predator and conspecific stimuli by reducing their activity, thus reducing visual detection and avoiding attack. Gammarus move out of the water column with pike stimulus because pike live in the region of the littoral zone, and remain in the water column with larval dragonfly stimuli, because they are benthic predators. This suggests Gammarus can detect antipredator stimuli from different types of predators and alter their behavior accordingly.
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