Susceptibility to predation affects trait-mediated indirect interactions by reversing interspecific competition

Area of Science:

• Ecology
• Marine Biology
• Behavioral Ecology

Background:

• Prey behavioral responses to predators are key in structuring ecological communities via trait-mediated indirect interactions.
• The influence of relative predation susceptibility on these interactions remains understudied.

Purpose of the Study:

• To investigate how chemical cues from the shore crab (Carcinus maenas) affect the foraging behavior of two intertidal gastropods: Littorina littorea and Gibbula umbilicalis.
• To determine if varying susceptibility to predation influences competitive interactions between these gastropod species.

Main Methods:

• Experimental exposure of gastropods to chemical cues from Carcinus maenas.
• Observation of foraging behavior and resource access in controlled conditions.
• Assessment of competitive interactions under varying predation threat levels.

Main Results:

• Littorina littorea, though morphologically more vulnerable, exhibited a stronger anti-predator response to crab cues, reducing its foraging.
• Gibbula umbilicalis, less vulnerable, benefited from Littorina's reduced foraging, gaining increased access to shared resources.
• The competitive interaction was reversed due to differential anti-predator responses.

Conclusions:

• Consumer susceptibility to predation significantly influences species interactions and community structure.
• Differential trait-mediated indirect interactions, driven by varied anti-predator responses, represent a crucial mechanism for non-consumptive predator effects in trophic interactions.