Temperature and food availability affect risk assessment in an ectotherm Govinda D. H. Lienart a, * , Matthew D. Mitchell a , Maud C. O. Ferrari b , Mark I. McCormick a a ARC Centre of Excellence for Coral Reef Studies, and School of Marine and Tropical Biology, James Cook University, Townsville, QLD, Australia b Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, Canada article info Article history: Received 22 August 2013 Initial acceptance 22 October 2013 Final acceptance 11 December 2013 Published online MS. number: 13-00697R Keywords: chemical alarm cue food availability Pomacentrus chrysurus risk assessment temperature Risk assessment in ectotherms is strongly affected by an organism’s energy expenditure and acquisition because these will alter the motivation to feed, which is balanced against antipredator behaviours. Temperature and food availability are known to affect the physiological condition of ectotherms, but how interactions between these variables may influence predatoreprey dynamics is still poorly understood. This study examined the interactive effects of food availability and temperature on the trade-offs be- tween predator avoidance behaviour and foraging in juveniles of a marine damselfish, Pomacentrus chrysurus. Predator avoidance behaviour was tested by exposing fish to chemical alarm cues obtained from skin extract of conspecifics. When detected, these cues elicit an antipredator response in fish, typically characterized by decreased foraging. Fish maintained under high food ration displayed distinct antipredator responses to chemical alarm cues, regardless of temperature. However, fish maintained in conditions of low food ration and 3  C above ambient temperature did not display an antipredator response when exposed to chemical alarm cues, whereas those in ambient temperature did. These re- sults suggest that individuals in low physiological condition because of limited food availability are more susceptible to increased temperature and may therefore take greater risks under predation threats to satisfy their energetic requirements. Ó 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Predation is known to drive behavioural patterns associated with foraging, reproduction and other fitness-related activities (Candolin, 1997; Houston, McNamara, & Hutchinson, 1993; Lima & Dill, 1990). Decisions made by an organism under the risk of pre- dation are often described as a trade-off between avoiding preda- tion and obtaining resources (Abrams, 1993; Lima, 1998). Predator avoidance decreases mortality rates but often at the cost of future growth and reproductive investment because of reduced foraging activity (Abrahams & Pratt, 2000; Cressler, King, & Werner, 2010). The extent to which individuals allocate their time to such activities depends on how an individual assesses the potential gains to overall fitness, given their current physiological state (Houston et al., 1993; Lima & Dill, 1990; Mathot & Dall, 2013; McNamara & Houston, 1986). Consequently, these state-dependent decisions can be heavily influenced by environmental parameters that impose an energetic cost, such as temperature (Abrahams, Mangel, & Hedges, 2007; Caraco et al., 1990). Although the importance of environmental parameters in determining antipredator strategies has been acknowledged, few studies have directly tested how in- teractions between different parameters affect risk assessment. Theoretical and empirical studies have stressed the importance of an individual’s physiological state as a driving component that should influence the trade-off between foraging and avoiding pre- dation. According to these studies, animals exposed to conditions of higher physiological demands should be willing to take greater risks in the presence of a predator (Caraco et al., 1990; Houston et al., 1993; Lima & Dill, 1990; Mangel & Clark, 1986). Killen, Marras, and McKenzie (2011) found that the combined effects of high meta- bolic rate and food deprivation on risk taking during foraging led to an increased tendency for fish to ignore a visual threat. In keeping with this finding, feeding history has been shown to affect risk- taking behaviour, with hungry animals reducing their antipredator response when presented with conspecific alarm cues (Chivers, Puttlitz, & Blaustein, 2000; Giaquinto & Volpato, 2001; McCormick & Larson, 2008; Smith, 1981). Although food availability and its ef- fect on physiological condition have been shown to influence behavioural decisions in fishes, there has been a lack of studies investigating how other environmental factors may further affect threat-sensitive trade-offs between the benefits of antipredator behaviour and foraging behaviour. For most organisms temperature is one of the major environ- mental influences on life history processes. This is especially true for ectothermic species, such as amphibians (Touchon & Warkentin, 2011), reptiles (Rhen, Schroeder, Sakata, Huang, & Crews, 2011) and * Correspondence: G. D. H. Lienart, School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia. E-mail address: govindadas.lienart@my.jcu.edu.au (G. D. H. Lienart). Contents lists available at ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav 0003-3472/$38.00 Ó 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.anbehav.2013.12.031 Animal Behaviour 89 (2014) 199e204