Proxies of energy expenditure for marine mammals: an experimental test of “the time trap”

Ladds, Monique; Rosen, David A. S.; Slip, David J.; Harcourt, Robert

doi:10.1038/s41598-017-11576-4

Cited by 23 publications

(18 citation statements)

References 43 publications

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“…Similarly, individual stroking costs in marine mammals and stride costs in terrestrial mammals can be used in combination with preferred stroke/stride rates as proxies for routine energy expenditure over short periods (Williams, Fuiman, et al, 2004; Williams, Kendall, et al, 2017; Williams, Blackwell, et al, 2017, but see Halsey, 2017; Ladds, Rosen, Slip, & Harcourt, 2017). Like terrestrial mammals for which the energetic cost per stride at routine speeds is nearly constant across body masses (mean = 7.0 J kg −1 stride −1 , SE = 0.6, n = 7; Heglund & Taylor, 1988), the energetic cost per stroke at preferred speeds generally appears to exhibit no significant trends across the body mass of marine mammals ( r 2 = 0.003, p = 0.85, n = 12, Figure 3c; table 3 in Williams et al., 2020).…”

Section: Landscape Energetics Of Large Predatory Mammalsmentioning

confidence: 99%

“…For example, a study evaluating the accuracy of stroke costs to measure energy expenditure of fur seals over a foraging trip that involved transit periods, diving and chasing and processing prey at sea found that this method poorly predicted total energy expended. In this case, the DBA method proved a better predictor of overall energy demand across long periods of interest (Halsey, 2017; Jeanniard‐du‐dot, Trites, Arnould, Speakman, & Guinet, 2016; Lads et al, 2017). Thus, when feasible, we recommend the use of DBA methods for measuring aerobic energy expenditure of carnivorous mammals, which appears to be a versatile metric for assessing both instantaneous and total energy expenditure, as well as for discriminating animal behaviours (Pagano & Williams, 2019).…”

Section: Landscape Energetics Of Large Predatory Mammalsmentioning

confidence: 99%

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Hunters versus hunted: New perspectives on the energetic costs of survival at the top of the food chain

et al. 2020

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Global biotic and abiotic threats, particularly from pervasive human activities, are progressively pushing large, apex carnivorous mammals into the functional role of mesopredator. Hunters are now becoming the hunted. Despite marked impacts on these animals and the ecosystems in which they live, little is known about the physiological repercussions of this role downgrading from ultimate to penultimate predator. Here we examine how such ecological role reversals alter the physiological processes associated with energy expenditure, and ultimately the cost of survival during peak performance. Taxonomic group, preferred habitat and domestication affected the capacity of the oxygen pathway to support high levels of aerobic performance by carnivorous mammals. Fear responses associated with anthropogenic threats also impacted aerobic performance. Allometric trends for three energetic metrics [maximum oxygen consumption, field metabolic rates (FMRs) and the cost per stride or stroke], showed distinct trends in aerobic capacity for different evolutionary lineages of mammalian predators. Cursorial canids that chase down prey demonstrated the highest relative maximum oxygen consumption rates (10–25 times resting levels) and FMRs, while ambush predators (i.e. felids) and diving marine mammals had aerobic capacities that were similar to or lower than sedentary domestic mammals of comparable size. The maximum energetic cost of performance for apex predators depended on whether the animals were hunters or the hunted. Escape responses were exceptionally costly for marine (narwhal Monodon monoceros) and terrestrial (mountain lion Puma concolor) locomotor specialists, as well as semi‐aquatic (polar bear Ursus maritimus) species; all showed a nearly two‐fold increase in peak energy expenditure when avoiding threats. As the duration and frequency of threats to wild species continue to grow, cumulative energetic costs are becoming more apparent. In view of this, attention to the energy demands of apex predators will provide vital predictive power to anticipate mismatches between a species' functional design and human‐induced pressures, and allow for the development of conservation strategies based on how species are built to survive. A free Plain Language Summary can be found within the Supporting Information of this article.

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Section: Landscape Energetics Of Large Predatory Mammalsmentioning

confidence: 99%

Section: Landscape Energetics Of Large Predatory Mammalsmentioning

confidence: 99%

Hunters versus hunted: New perspectives on the energetic costs of survival at the top of the food chain

et al. 2020

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“…There have been a great number of studies in recent years that have attempted to link data from ETDs, such as accelerometry, activity partitioning, movement data or dive profiles, to robust models of energy usage over time. Using tag data that have not been properly calibrated to energy usage can be problematic and lead to spurious correlations and risks falling into the so-called 'time-trap' (merging measurements such that time is on both sides of an equation, as discussed in [40,66], but may be difficult to assess for certain species.…”

Section: Conclusion Caveats and Future Directionsmentioning

confidence: 99%

Best practice recommendations for the use of external telemetry devices on pinnipeds

et al. 2019

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Pinnipeds spend large portions of their lives at sea, submerged, or hauled-out on land, often on remote offshore islands. This fundamentally limits access by researchers to critical parts of pinniped life history and has spurred the development and implementation of a variety of externally attached telemetry devices (ETDs) to collect information about movement patterns, physiology and ecology of marine animals when they cannot be directly observed. ETDs are less invasive and easier to apply than implanted internal devices, making them more widely used. However, ETDs have limited retention times and their use may result in negative short-and long-term consequences including capture myopathy, impacts to energetics, behavior, and entanglement risk. We identify 15 best practice recommendations for the use of ETDs with pinnipeds that address experimental justification, animal capture, tag design, tag attachment, effects assessments, preparation, and reporting. Continued improvement of best practices is critical within the framework of the Three Rs (Reduction, Refinement, Replacement); these best practice recommendations provide current guidance to mitigate known potential negative outcomes for individuals and local populations. These recommendations were developed specifically for pinnipeds; however, they may also be applicable to studies of other marine taxa. We conclude with four desired future directions for the use of ETDs in technology development, validation studies, experimental designs and data sharing.

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“…Dynamic body acceleration (DBA) or stroke rate, measured from accelerometers was promoted as a way to directly estimate energy expenditure in wild fur seals ( Jeanniard-du Dot et al, 2016 ). However, this approach has recently been shown to be flawed, as the apparent relationship between DBA and energy expenditure is in fact time correlated with time, as both the independent variable (energy) and dependent variable (DBA or strokes) are both summed, thus introducing time into both sides of the equation ( Halsey, 2017 ; Ladds et al, 2017a ). Thus, a new way of estimating energy expenditure is needed.…”

Section: Introductionmentioning

confidence: 99%

Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates

Ladds

Salton

Hocking

et al. 2018

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BackgroundAccurate time-energy budgets summarise an animal’s energy expenditure in a given environment, and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires an estimate of time spent in different activities and of the energetic cost of that activity. Bio-loggers (e.g., accelerometers) may provide a solution for monitoring animals such as fur seals that make long-duration foraging trips. Using low resolution to record behaviour may aid in the transmission of data, negating the need to recover the device.MethodsThis study used controlled captive experiments and previous energetic research to derive time-energy budgets of juvenile Australian fur seals (Arctocephalus pusillus) equipped with tri-axial accelerometers. First, captive fur seals and sea lions were equipped with accelerometers recording at high (20 Hz) and low (1 Hz) resolutions, and their behaviour recorded. Using this data, machine learning models were trained to recognise four states—foraging, grooming, travelling and resting. Next, the energetic cost of each behaviour, as a function of location (land or water), season and digestive state (pre- or post-prandial) was estimated. Then, diving and movement data were collected from nine wild juvenile fur seals wearing accelerometers recording at high- and low- resolutions. Models developed from captive seals were applied to accelerometry data from wild juvenile Australian fur seals and, finally, their time-energy budgets were reconstructed.ResultsBehaviour classification models built with low resolution (1 Hz) data correctly classified captive seal behaviours with very high accuracy (up to 90%) and recorded without interruption. Therefore, time-energy budgets of wild fur seals were constructed with these data. The reconstructed time-energy budgets revealed that juvenile fur seals expended the same amount of energy as adults of similar species. No significant differences in daily energy expenditure (DEE) were found across sex or season (winter or summer), but fur seals rested more when their energy expenditure was expected to be higher. Juvenile fur seals used behavioural compensatory techniques to conserve energy during activities that were expected to have high energetic outputs (such as diving).DiscussionAs low resolution accelerometry (1 Hz) was able to classify behaviour with very high accuracy, future studies may be able to transmit more data at a lower rate, reducing the need for tag recovery. Reconstructed time-energy budgets demonstrated that juvenile fur seals appear to expend the same amount of energy as their adult counterparts. Through pairing estimates of energy expenditure with behaviour this study demonstrates the potential to understand how fur seals expend energy, and where and how behavioural compensations are made to retain constant energy expenditure over a short (dive) and long (season) period.

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Proxies of energy expenditure for marine mammals: an experimental test of “the time trap”

Cited by 23 publications

References 43 publications

Hunters versus hunted: New perspectives on the energetic costs of survival at the top of the food chain

Hunters versus hunted: New perspectives on the energetic costs of survival at the top of the food chain

Best practice recommendations for the use of external telemetry devices on pinnipeds

Using accelerometers to develop time-energy budgets of wild fur seals from captive surrogates

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