Diurnal foraging of a wild coral‐reef fish Parapercis australis in relation to late‐summer temperatures

Abstract

In situ observations of diurnal foraging behaviour of a common site-attached shallow reef mesopredator Parapercis australis during late summer, revealed that although diet composition was unaffected by seawater temperature (range 28.3-32.4°C), feeding strikes and distance moved increased with temperature up to 30.5°C, beyond which they sharply declined, indicative of currently living beyond their thermal optimum. Diel feeding strikes and distance moved were however, tightly linked to ambient temperature as it related to the population's apparent thermal optimum, peaking at times when it was approached (1230 and 1700 h) and declining up to four fold at times deviating from this. These findings suggest that although this population may be currently living beyond its thermal optimum, it copes by down regulating energetically costly foraging movement and consumption and under future oceanic temperatures, these behavioural modifications are probably insufficient to avoid deleterious effects on population viability without the aid of long-term acclimation or adaptation.

The influence of thermal extremes on coral reef fish behaviour in the Persian Gulf

“…(Pörtner and Knust, 2007; Pörtner and Farrell 2008; Munday 2012). The reduction in activity observed in P. trichrourus, is in line with recent work suggesting that, when exposed to short-term higher than average SSTs, coral reef fish may temporarily mitigate bioenergetic inefficiency through reduction in energetically costly activities, as well as through changes in diet (Nowicki et al 2012; Johansen et al 2014; Scott et al 2017; Chase et al 2018). However, such strategies may not be sufficient to sustain prolonged periods (i.e.…”

“…Although increasing variance in global SSTs may directly impact coral reef fish community biodiversity (Pratchett et al 2015; Pecl et al 2017; Hughes et al 2018), coral reef fish populations might be able to mitigate the effect of rapidly changing environments through behavioural plasticity (Nagelkerken and Munday 2016; Scott et al 2017; Shraim et al 2017; Chase et al 2018). We examined the impact of seasonal changes in biotic and abiotic conditions on distance from refugia, activity and feeding ecology of the pale-tail damselfish P. trichrourus within the southern Gulf.…”

“…months) of extreme temperature (Rummer et al 2014; Rodgers et al 2018). For example, reductions in food intake and quality, coupled with low aerobic scope under extreme temperatures, can disrupt an ectothermic organism’s energy balance, with substantially less energy available for long-term maintenance, growth and reproduction (Gillooly et al 2001; Pörtner et al 2010; Neuheimer et al 2011), impacting individual fitness and potentially survival (Chase et al 2018).…”

“…Despite this, a growing body of research suggests adaptive behavioural plasticity in response to temperature increases in coral reef fishes, often through temporary reductions in aerobically-costly behaviours (i.e. activity and feeding) associated with increased (short-term) environmental variance (Nowicki et al 2012; Johansen et al 2014; Scott et al 2017; Chase et al 2018). Nevertheless, how well coral reef fishes will cope with ocean warming scenarios (ICCP 2014), and by what mechanisms, is still generally poorly understood.…”

The shape of abundance distributions across temperature gradients in reef fishes

“…Whilst some species within each guild can have high ecological performance at the thermal guild 'barrier' (~23°C) in both guilds, some species segregate strongly at this barrier and do not occur in both guilds. reef fishes could be considered an ideal 'model' taxon, given the relatively low thermal heterogeneity and high spatial autocorrelation of temperature in subtidal marine systems (Steele & Henderson 1994), leading to a reduced capacity to behaviourally thermoregulate (but see Chase et al 2018). Furthermore, terrestrial species which strongly regulate body temperatureseither physiologically (hibernation, endothermy) or behaviourally (burrowing, seeking shade)may be less likely to show reduced performance at suboptimal temperatures.…”