Digestive and locomotor capacity show opposing responses to changing food availability in an ambush predatory fish

Fu, S.-J., Peng, J. and Killen, S. S. (2018) Digestive and locomotor capacity show opposing responses to changing food availability in an ambush predatory fish. Journal of Experimental Biology, 221(12), jeb173187. (doi: 10.1242/jeb.173187) (PMID:29636411) (PMCID:PMC6031316)

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Metabolic rates vary widely within species, but little is known about how variation in the “floor” (i.e. standard metabolic rate in ectotherms; SMR) and “ceiling” (maximum metabolic rate; MMR) for an individual's aerobic scope (AS) are linked with the digestive and locomotor function. Any links among metabolic traits and aspects of physiological performance may also be modulated by fluctuations in food availability. This study followed changes in SMR, MMR, and digestive and locomotor capacity in Southern catfish (Silurus meridionalis) throughout 15 days of food deprivation and 15 days of refeeding. Individuals down-regulated SMR during food deprivation and showed only a 10% body mass decrease during this time. While critical swim speed (Ucrit), was robust to food-deprivation, digestive function decreased after fasting with a reduced peak oxygen uptake during specific dynamic action (SDA) and prolonged SDA duration. During refeeding, individuals displayed rapid growth and digestive function recovered to pre-fasting levels. However, refed fish showed a lower Ucrit than would be expected for their increased body length and in comparison to measures at the start of the study. Reduced swimming ability may be a consequence of compensatory growth: growth rate was negatively correlated with changes in Ucrit during refeeding. Southern catfish down-regulate digestive function to reduce energy expenditure during food deprivation, but regain digestive capacity during refeeding, potentially at the cost of decreased swimming performance. The plasticity of maintenance requirements suggests that SMR is a key fitness trait for in this ambush predator. Shifts in trait correlations with food availability suggest that the potential for correlated selection may depend on context.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Killen, Professor Shaun
Authors: Fu, S.-J., Peng, J., and Killen, S. S.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Journal of Experimental Biology
Publisher:Company of Biologists
ISSN (Online):1477-9145
Published Online:10 April 2018
Copyright Holders:Copyright © 2018 The Company of Biologists Ltd
First Published:First published in Journal of Experimental Biology 221(12): jeb173187
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