Aggression supersedes individual oxygen demand to drive group air-breathing in a social catfish

Killen, S. S. , Esbaugh, A. J., Martins, N., Rantin, F. T. and McKenzie, D. J. (2018) Aggression supersedes individual oxygen demand to drive group air-breathing in a social catfish. Journal of Animal Ecology, 87(1), pp. 223-234. (doi: 10.1111/1365-2656.12758) (PMID:28940526) (PMCID:PMC5765462)

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1. Group-living is widespread among animals and comes with numerous costs and benefits. To date, research examining group-living has focused on trade-offs surrounding foraging, while other forms of resource acquisition have been largely overlooked. 2. Air breathing has evolved in many fish lineages, allowing animals to obtain oxygen in hypoxic aquatic environments. Breathing air increases the threat of predation, so some species perform group air breathing, to reduce individual risk. Within species, air breathing can be influenced by metabolic rate as well as personality, but the mechanisms of group air breathing remain unexplored. It is conceivable that keystone individuals with high metabolic demand or intrinsic tendency to breathe air may drive social breathing, especially in hypoxia. 3. We examined social air breathing in African sharptooth catfish Clarias gariepinus, to determine whether individual physiological traits and spontaneous tendency to breathe air influence the behaviour of entire groups, and whether such influences vary in relation to aquatic oxygen availability. 4. We studied eleven groups of four catfish in a laboratory arena and recorded air-breathing behaviour, activity, and agonistic interactions at varying levels of hypoxia. Bimodal respirometry was used to estimate individual standard metabolic rate (SMR) and the tendency to utilise aerial oxygen when alone. 5. Fish took more air breaths in groups as compared to when they were alone, regardless of water oxygen content, and displayed temporally clustered air-breathing behaviour, consistent with existing definitions of synchronous air breathing. However, groups displayed tremendous variability in surfacing behaviour. Aggression by dominant individuals within groups was the main factor influencing air breathing of the entire group. There was no association between individual SMR, or the tendency to obtain oxygen from air when in isolation, and group air breathing. 6. For C. gariepinus, synchronous air breathing is strongly influenced by agonistic interactions, which may expose subordinate individuals to risk of predation. Influential individuals exerted an overriding effect on risk-taking by the entire group, for reasons independent of their physiological oxygen requirements. Overall, this illustrates that social context can obscure interactions between an individual's physiological and behavioural traits and their tendency to take risks to obtain resources.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Killen, Professor Shaun
Authors: Killen, S. S., Esbaugh, A. J., Martins, N., Rantin, F. T., and McKenzie, D. J.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Journal of Animal Ecology
ISSN (Online):1365-2656
Published Online:20 September 2017
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Journal of Animal Ecology 87(1): 223-234
Publisher Policy:Reproduced under a Creative Commons License

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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
171278PHYSFISHShaun KillenEuropean Research Council (ERC)Killen, Dr ShaunInstitute of Biodiversity, Animal Health and Comparative Medicine