Complex predator-prey interactions and predator intimidation among crayfish, piscivorous fish, and small benthic fish

Area of Science:

• Ecology
• Behavioral Ecology
• Aquatic Ecosystems

Background:

• Predator-prey interactions are fundamental to ecosystem structure.
• Understanding how multiple predators influence prey behavior is crucial for ecological studies.
• Johnny darters (Etheostoma nigrum) are small prey fish vulnerable to predation.

Purpose of the Study:

• To investigate the interactive effects of two predators, crayfish (Orconectes rusticus) and smallmouth bass (Micropterus dolomieui), on the behavior of johnny darters.
• To determine how complementary foraging behaviors of predators influence prey vulnerability.
• To assess the lingering effects of predator intimidation on prey behavior.

Main Methods:

• Observational study of johnny darter behavior under different predator treatments (bass only, crayfish only, both).
• Quantification of darter activity levels and shelter use.
• Assessment of behavioral changes following predator exposure and removal.

Main Results:

• Darters significantly reduced activity and increased shelter use when only smallmouth bass were present.
• Crayfish alone did not significantly alter darter activity or shelter use compared to controls.
• When both predators were present, crayfish increased darter activity and eviction from shelters, enhancing vulnerability to bass.
• Smallmouth bass increased darter vulnerability to crayfish by driving them to seek shelter occupied by crayfish.
• Intimidation effects of bass on darters persisted for at least 24 hours after bass removal.

Conclusions:

• Complex predator-prey interactions can arise when predators have complementary foraging strategies.
• Crayfish and smallmouth bass can indirectly increase each other's predation success on johnny darters.
• Predator intimidation can have long-lasting behavioral effects on prey, influencing their survival even in the absence of the predator.