How does school size affect tail beat frequency in turbulent water?

Area of Science:

• Marine Biology
• Hydrodynamics
• Animal Behavior

Background:

• Previous studies on fish schooling energy savings used idealized laminar flow.
• The impact of turbulent flows and varying group sizes on schooling energetics remains under-explored.

Purpose of the Study:

• To investigate if schooling is more energetically economical in quantified turbulent flow.
• To determine how group size moderates energy savings in non-laminar water flow.

Main Methods:

• Measured tail beat frequency (tbf) in sea bass swimming alone, in groups of 3, or 6.
• Used video analysis to track fish movement, flow rates, and turbulence levels.
• Employed a repeated-measures design to assess individual responses within different group contexts.

Main Results:

• Fish showed reduced tbf in groups, suggesting potential energy savings, but these were attenuated by turbulence.
• Tail beat frequency was unrelated to flow rate for solitary or 3-fish groups but decreased with flow in 6-fish groups.
• Increased turbulence led to higher tbf across all group sizes.

Conclusions:

• Group size can moderate the effects of water flow on fish swimming kinematics in turbulent conditions.
• Schooling benefits in terms of energy cost are complex and influenced by flow dynamics and group structure.
• Further research is needed to fully understand the energetic implications of schooling in natural, turbulent environments.