Defining the reaction space of predator-prey interactions
This dissertation contributed to the call for a greater comprehension of sensory ecology within predator-prey interactions, particularly in the non-consumptive effects (NCEs) of predators. I investigated how stimulus modality, predator movement, environmental transmission, prey sensory ecology, pollution, and the interaction of these factors modify prey behavioral responses to predators. Specifically, I experimentally tested three research questions: 1) how the reaction space of predators with different hunting modes in different flow environments altered prey behavior, 2) how modulating signal intensity and prey detection thresholds altered the reaction space, and 3) how the exposure to anthropogenic chemicals altered the reaction space of prey.
First, I placed prey (crayfish) in two different environments (flow and no flow) in one of three predator treatments (active predator [bass], sit-and-wait predator [catfish], no predator) and monitored the behavior of the crayfish in a resource patchy environment. Predator hunting mode changed prey behavior, but only in flowing water that would enhance the transmission of predator cues. The most significant interaction between predator treatment and flow environment was found with the active predator in flowing habitats, but this same interaction did not alter NCEs from a sit-and-wait predator. Second, I exposed virile and rusty crayfish to low, medium, or high concentration of odor from largemouth bass and to controls without bass odor and monitored crayfish. The results showed that the behavior of virile crayfish was significantly altered across concentrations more than rusty crayfish, indicating that the virile crayfish may have larger reaction space. Finally, I exposed virile and rusty crayfish to a pesticide (carbaryl) then placed the crayfish in a two-choice flume containing predator odor and clean river water to monitor their behavior. I found that the exposure to a carbaryl did not affect the anti-predator behavior of either species.
The findings show that each factor of the reaction space is important in understanding and altering NCEs of predators. Additionally, NCEs may be hidden unless the interaction of factors is taken into consideration. Investigating the sensory environment of predator-prey interactions is crucial for better understanding the mechanisms driving the NCEs of predators and their consequences.