Temperature alters the physiological response of spiny lobsters under predation risk.

Felipe A Briceño,Elias T Polymeropoulos,Gretta T Pecl,Iván A Hinojosa,Quinn P Fitzgibbon,Steven Cooke

doi:10.1093/conphys/coaa065

Abstract

Predation risk can strongly shape prey ecological traits, with specific anti-predator responses displayed to reduce encounters with predators. Key environmental drivers, such as temperature, can profoundly modulate prey energetic costs in ectotherms, although we currently lack knowledge of how both temperature and predation risk can challenge prey physiology and ecology. Such uncertainties in predator–prey interactions are particularly relevant for marine regions experiencing rapid environmental changes due to climate change. Using the octopus (Octopus maorum)–spiny lobster (Jasus edwardsii) interaction as a predator–prey model, we examined different metabolic traits of sub adult spiny lobsters under predation risk in combination with two thermal scenarios: ‘current’ (20°C) and ‘warming’ (23°C), based on projections of sea-surface temperature under climate change. We examined lobster standard metabolic rates to define the energetic requirements at specific temperatures. Routine metabolic rates (RMRs) within a respirometer were used as a proxy of lobster activity during night and day time, and active metabolic rates, aerobic scope and excess post-exercise oxygen consumption were used to assess the energetic costs associated with escape responses (i.e. tail-flipping) in both thermal scenarios. Lobster standard metabolic rate increased at 23°C, suggesting an elevated energetic requirement (39%) compared to 20°C. Unthreatened lobsters displayed a strong circadian pattern in RMR with higher rates during the night compared with the day, which were strongly magnified at 23°C. Once exposed to predation risk, lobsters at 20°C quickly reduced their RMR by ~29%, suggesting an immobility or ‘freezing’ response to avoid predators. Conversely, lobsters acclimated to 23°C did not display such an anti-predator response. These findings suggest that warmer temperatures may induce a change to the typical immobility predation risk response of lobsters. It is hypothesized that heightened energetic maintenance requirements at higher temperatures may act to override the normal predator-risk responses under climate-change scenarios.

Highlights

Changes in predator–prey interactions, as a function of ocean warming, are resulting in considerable challenges for biological systems, in regions experiencing significant warming such as south-eastern Australia (Hobday and Pecl, 2014)
(2) An increase in RMRn+risk between 1 and 3 h after octopus kairomone exposure observed at both temperatures without any difference between predation risk scenarios
The rate of decline was slightly more in RMRn+risk than RMRnrisk at 20◦C according to the interaction predation risk ∗ hour (χ 2 = 3.357, df = 1, P = 0.067)

Summary

Introduction

Changes in predator–prey interactions, as a function of ocean warming, are resulting in considerable challenges for biological systems, in regions experiencing significant warming such as south-eastern Australia (Hobday and Pecl, 2014). In Tasmania, warming temperatures have facilitated increased larval survival and settlement of a habitat-modifying sea urchin (Centrostephanus rodgersii) resulting in the formation of urchin barrens, i.e. reef areas that have been stripped of most algae (see Ling et al, 2009; Johnson et al, 2011) This has created structural and functional changes across multiple ecosystem levels (Ling et al, 2009; Johnson et al, 2011), with uncertain implications for key ecologically and economically important species, such as the southern rock (spiny) lobster Jasus edwardsii (Pecl et al, 2009; Johnson et al, 2011; Hinojosa et al, 2015; Pecl et al, 2019). Changes in octopus abundance and distribution are already occurring in the south-eastern Australian region(e.g. Ramos et al, 2014), as cephalopods are quickly responsive to temperature changes (Robin et al, 2014; Rodhouse et al, 2014; Doubleday et al, 2016)

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Results

Conclusion