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

Halsey, L. G., Wright, S., Racz, A., Metcalfe, J. D. and Killen, S. S. (2018) How does school size affect tail beat frequency in turbulent water? Comparative Biochemistry and Physiology. Part A: Molecular and Integrative Physiology, 218, pp. 63-69. (doi:10.1016/j.cbpa.2018.01.015) (PMID:29408691)

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Abstract

The energy savings experienced by fish swimming in a school have so far been investigated in an near-idealised experimental context including a relatively laminar water flow. The effects of explicitly turbulent flows and different group sizes are yet to be considered. Our repeated-measures study is a first step in addressing both of these issues: whether schooling is more energetically economical for fish when swimming in a quantified non-laminar flow and how this might be moderated by group size. We measured tail beat frequency (tbf) in sea bass swimming in a group of 3 or 6, or singly. Video data enabled us to approximately track the movements of the fish during the experiments and in turn ascertain the water flow rates and turbulence levels experienced for each target individual. Although the fish exhibited reductions in tbf during group swimming, which may indicate some energy savings, these savings appear to be attenuated, presumably due to the water turbulence and the movement of the fish relative to each other. Surprisingly, tbf was unrelated to flow rate when the fish were swimming singly or in a group of three, and decreased with increasing flow rates when swimming in a group of six. However, the fish increased tbf in greater turbulence at all group sizes. Our study demonstrates that under the challenging and complex conditions of turbulent flow and short-term changes in school structure, group size can moderate the influences of water flow on a fish's swimming kinematics, and in turn perhaps their energy costs. Summary statement: The energy savings that sea bass experience from schooling are affected by flow speed or turbulence, moderated by group size.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Killen, Dr Shaun and Racz, Miss Anita
Authors: Halsey, L. G., Wright, S., Racz, A., Metcalfe, J. D., and Killen, S. S.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Comparative Biochemistry and Physiology. Part A: Molecular and Integrative Physiology
ISSN:1095-6433
ISSN (Online):1531-4332
Published Online:01 February 2018

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
594261The Influence of Individual Physiology on Group Behaviour in Fish SchoolsShaun KillenNatural Environment Research Council (NERC)NE/J019100/1RI BIODIVERSITY ANIMAL HEALTH & COMPMED