Association behavior between sand tiger sharks and round scad is driven by mesopredators

Area of Science:

• Marine ecology
• Behavioral ecology
• Predator-prey dynamics

Background:

• Behaviorally-mediated indirect interactions are understudied in marine systems due to observation challenges.
• Understanding these interactions is crucial for marine food web dynamics.

Purpose of the Study:

• To investigate the association behavior between round scad (Decapterus punctatus) and sand tiger sharks (Carcharias taurus).
• To determine if sand tiger sharks provide a predation refuge for round scad in the presence of mesopredators.

Main Methods:

• Analysis of 216 underwater videos from SharkCam at a hard bottom site off Cape Fear, North Carolina.
• Observation of round scad and six mesopredator species in association with sand tiger sharks.
• Categorization of interactions into no visible interaction, loosely associated, or tightly associated.

Main Results:

• Round scad were significantly more likely to associate loosely or tightly with sand tiger sharks when mesopredators were present.
• This suggests sharks act as a predation refuge for round scad.
• While sharks may not directly benefit, round scad association enhances predation opportunities for sharks by attracting mesopredators.

Conclusions:

• Sand tiger sharks provide a predation refuge for round scad, a behaviorally-mediated indirect interaction.
• This interaction has significant implications for trophic energy transfer and mesopredator control on hard bottom ecosystems.
• Further research into behaviorally-mediated interactions is valuable for understanding marine community dynamics.