Abstract Accurate estimates of penguin energetics would represent an important contribution to our understanding of the trophodynamics of the Southern Ocean ecosystem and our ability to predict effects of environmental change on these species. We used the heart rate-rate of oxygen consumption technique to estimate rate of energy expenditure in adult king penguins raising a chick, in combination with data from the literature on changes in adult mass, chick energy requirements, and prey energy density. Our model estimated a variety of energetic costs and quantities of prey consumption related to raising a king penguin chick during the austral summer. The total energy requirements of a king penguin chick at the Crozet Archipelago from hatching until reaching a mass of 8 kg 90 d later is 271 MJ, representing the consumption of 38.4 kg of myctophid fish. A successfully breeding male requires 0.78 kg d(-1) of fish during the entirety of the incubation period and 1.14 kg d(-1) during the subsequent 90 d of chick rearing. Assuming the same energy requirements for females, the estimated 580,000 pairs of king penguins that breed successfully at Crozet each year, together with their chicks, consume a total of around 190,000 tons of fish during the incubation and summer rearing periods combined. If, due to depletion of fish stocks, the diet of breeders and chicks during the summer becomes identical to the typical diet of adults during the austral winter, the mass of prey required by both adults and chicks combined (where the chick still reaches 8 kg after 90 d) would increase by more than 25%.

Because fasting king penguins (Aptenodytes patagonicus) need to conserve energy, it is possible that they exhibit particularly low metabolic rates during periods of rest. We investigated the behavioral and physiological aspects of periods of minimum metabolic rate in king penguins under different circumstances. Heart rate (f(H)) measurements were recorded to estimate rate of oxygen consumption during periods of rest. Furthermore, apparent respiratory sinus arrhythmia (RSA) was calculated from the f(H) data to determine probable breathing frequency in resting penguins. The most pertinent results were that minimum f(H) achieved (over 5 min) was higher during respirometry experiments in air than during periods ashore in the field; that minimum f(H) during respirometry experiments on water was similar to that while at sea; and that RSA was apparent in many of the f(H) traces during periods of minimum f(H) and provides accurate estimates of breathing rates of king penguins resting in specific situations in the field. Inferences made from the results include that king penguins do not have the capacity to reduce their metabolism to a particularly low level on land; that they can, however, achieve surprisingly low metabolic rates at sea while resting in cold water; and that during respirometry experiments king penguins are stressed to some degree, exhibiting an elevated metabolism even when resting.

Penguins are known to have high pedestrian locomotory costs in comparison to other cursorial birds, but the ecological consequences of this difference have received limited attention. Here we present a method for the accurate estimation of onshore energetics based on measurements of body mass, simple morphometrics and distance moved. The method is shown to be similarly accurate to other field-based estimates of energy expenditure, but has the advantage of logistical simplicity. King penguins spend 30-50% of their time ashore and may walk distances of several kilometres to and from their breeding colonies. However, in such cases the total energetic cost of pedestrian locomotion is estimated to be only 1.0% of the energy expended whilst ashore. Thus, despite a high instantaneous cost, pedestrian locomotion is a small and possibly negligible component of total energy turnover in king penguins.

In endotherms, regulation of the degree of mitochondrial coupling affects cell metabolic efficiency. Thus it may be a key contributor to minimising metabolic rate during long periods of fasting. The aim of the present study was to investigate whether variation in mitochondrial avian uncoupling proteins (avUCP), as putative regulators of mitochondrial oxidative phosphorylation, may contribute to the ability of king penguins (Aptenodytes patagonicus ) to withstand fasting for several weeks. After 20 days of fasting, king penguins showed a reduced rate of whole animal oxygen consumption (VO2 ;-33%) at rest together with a reduced abundance of avUCP and peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC1-alpha) mRNA in pectoralis muscle (-54%,-36% respectively). These parameters were restored after the birds had been re-fed for 3 days. Further, in recently fed, but not in fasted, penguins, isolated muscle mitochondria showed a GDP-inhibited, fatty acid plus superoxide-activated respiration, indicating the presence of a functional UCP. It was calculated that variation in mitochondrial UCP-dependent respiration in vitro may contribute to nearly 20% of the difference in resting VO2 between fed or re-fed penguins and fasted penguins measured in vivo. These results suggest that the lowering of avUCP activity during periods of long-term energetic restriction may contribute to the reduction in metabolic rate and hence the ability of king penguins to face prolonged periods of fasting. Key words: avian UCP, penguin, metabolic rate, mitochondria, oxidative capacity.

We measured the effects of exposure to hypoxia (15% and 11% oxygen) and hypercapnia (up to 4.5% carbon dioxide) on rates of respiratory gas exchange both between and during dives in tufted ducks, Aythya fuligula, to investigate to what extent these may explain changes in diving behaviour. As found in previous studies, the ducks decreased dive duration (t(d)) and increased surface duration when diving from a hypoxic or hypercapnic gas mix. In the hypercapnic conditions, oxygen consumption during the dive cycle was not affected. Oxygen uptake between dives was reduced by only 17% when breathing a hypoxic gas mix of 11% oxygen. However, estimates of the rate of oxygen metabolism during the foraging periods of dives decreased nearly threefold in 11% oxygen. Given that tufted ducks normally dive well within their aerobic dive limits and that they significantly reduced their t(d) during hypoxia, it is not at all clear why they make this physiological adjustment.

The rate of oxygen uptake at the surface between dives was measured for four tufted ducks, Aythya fuligula, during bouts of foraging dives to a depth of 1.8 m. The ducks surfaced into a respirometer box after each dive so that the rate of oxygen uptake ((O(2))) could be measured.(O(2)) decreased over time at the surface and there was a particularly rapid phase of oxygen uptake for approximately the first 3s. The specific shape of the oxygen uptake curve is dependent upon the duration of the preceding dive. The uptake curve after longer dives was significantly steeper during the first 3s at the surface than after shorter dives, although (O(2)) after the first 3s was not significantly different between these two dive duration bins. Thus, the mean total oxygen uptake (V(O(2))) was higher after surface periods following longer dives. Due to the high (O(2)) during the initial part of the surface period, the curve associated with longer dives was statistically biphasic, with the point of inflection at 3.3s. The curve for shorter dives was not statistically biphasic. The birds may increase their respiratory frequency during the first 3s after longer dives, producing the increased (O(2)), which would enable the birds to resaturate their oxygen stores more rapidly in response to the increased oxygen depletion of the longer submergence time.

Studies on diving ducks indicate that the carotid bodies affect dive duration when the birds are hypoxic before a dive but not when they are hypercapnic. When close to their critical concentrations (beyond which the ducks will not dive), both oxygen and carbon dioxide reduce dive duration but hypercapnia has a much larger influence than hypoxia on surface duration. Also, excessive removal of carbon dioxide before a dive may be as important a factor in preparing for that dive as the replacement of the oxygen used during the previous dive. This observation is compatible with a physiological model of the control of diving behaviour in the Weddell seal which emphasises the significance of the level of carbon dioxide in the blood perfusing the brain.

Cormorants hunt both benthic (sedentary) and pelagic (motile) prey but it is not known if the energy costs of foraging on these prey differ. We used respirometry to measure the costs of diving in double-crested cormorants (Phalacrocorax auritus) foraging either for sedentary (fish pieces) or motile (juvenile salmon) prey in a deep dive tank. Short dives for sedentary prey were more expensive than dives of similar duration for motile prey (e.g. 20% higher for a 10s dive) whereas the reverse was true for long dives (i.e. long dives for motile prey were more expensive than for sedentary prey). Across dives of all durations, the foraging phase of the dive was more expensive when the birds hunted motile prey, presumably due to pursuit costs. The period of descent in all the dives undertaken appears to have been more expensive when the birds foraged on sedentary prey, probably due to a higher swimming speed during this period.

1. Time and energy are key currencies in animal ecology, and judicious management of these is a primary focus for natural selection. At present, however, there are only two main methods for estimation of rate of energy expenditure in the field, heart rate and doubly labelled water, both of which have been used with success; but both also have their limitations. 2. The deployment of data loggers that measure acceleration is emerging as a powerful tool for quantifying the behaviour of free-living animals. Given that animal movement requires the use of energy, the accelerometry technique potentially has application in the quantification of rate of energy expenditure during activity. 3. In the present study, we test the hypothesis that acceleration can serve as a proxy for rate of energy expenditure in free-living animals. We measured rate of energy expenditure as rates of O(2) consumption () and CO(2) production () in great cormorants (Phalacrocorax carbo) at rest and during pedestrian exercise. and were then related to overall dynamic body acceleration (ODBA) measured with an externally attached three-axis accelerometer. 4. Both and were significantly positively associated with ODBA in great cormorants. This suggests that accelerometric measurements of ODBA can be used to estimate and and, with some additional assumptions regarding metabolic substrate use and the energy equivalence of O(2) and CO(2), that ODBA can be used to estimate the activity specific rate of energy expenditure of free-living cormorants. 5. To verify that the approach identifies expected trends in from situations with variable power requirements, we measured ODBA in free-living imperial cormorants (Phalacrocorax atriceps) during foraging trips. We compared ODBA during return and outward foraging flights, when birds are expected to be laden and not laden with captured fish, respectively. We also examined changes in ODBA during the descent phase of diving, when power requirements are predicted to decrease with depth due to changes in buoyancy associated with compression of plumage and respiratory air. 6. In free-living imperial cormorants, ODBA, and hence estimated , was higher during the return flight of a foraging bout, and decreased with depth during the descent phase of a dive, supporting the use of accelerometry for the determination of activity-specific rate of energy expenditure.

This review discusses the advancements in our understanding of the physiology and behaviour of avian diving that have been underpinned by optimal foraging theory and the testing of optimal models. To maximise their foraging efficiency during foraging periods, diving birds must balance numerous factors that are directly or indirectly related to the replenishment of the oxygen stores and the removal of excess carbon dioxide. These include (1) the time spent underwater (which diminishes the oxygen supply, increases carbon dioxide levels and may even include a build up of lactate due to anaerobic metabolism),(2) the time spent at the surface recovering from the previous dive and preparing for the next (including reloading their oxygen supply, decreasing their carbon dioxide levels and possibly also metabolising lactate) and (3) the trade-off between maximising oxygen reserves for consumption underwater by taking in more air to the respiratory system, and minimising the energy costs of positive buoyancy caused by this air, to maximise the time available underwater to forage. Due to its importance in avian diving, replenishment of the oxygen stores has become integral to models of optimal diving, which predict the time budgeting of animals foraging underwater. While many of these models have been examined qualitatively, such tests of predictive trends appear fallible and only quantifiable support affords strong evidence of their predictive value. This review describes how the quantification of certain optimal diving models, using tufted ducks, indeed demonstrates some predictive success. This suggests that replenishment of the oxygen stores and removal of excess carbon dioxide have significant influences on the duration of the surface period between dives. Nevertheless, present models are too simplistic to be robust predictors of diving behaviour for individual animals and it is proposed that they require refinement through the incorporation of other variables that also influence diving behaviour such as, perhaps, prey density and predator avoidance.

The oxygen store/usage hypothesis suggests that larger animals are able to dive for longer and hence deeper because oxygen storage scales isometrically with body mass, whereas oxygen usage scales allometrically with an exponent <1 (typically 0.67-0.75). Previous tests of the allometry of diving tend to reject this hypothesis, but they are based on restricted data sets or invalid statistical analyses (which assume that every species provides independent information). Here we apply information-theoretic statistical methods that are phylogenetically informed to a large data set on diving variables for birds and mammals to describe the allometry of diving. Body mass is strongly related to all dive variables except dive : pause ratio. We demonstrate that many diving variables covary strongly with body mass and that they have allometric exponents close to 0.33. Thus, our results fail to falsify the oxygen store/usage hypothesis. The allometric relationships for most diving variables are statistically indistinguishable for birds and mammals, but birds tend to dive deeper than mammals of equivalent mass. The allometric relationships for all diving variables except mean dive duration are also statistically indistinguishable for all major taxonomic groups of divers within birds and mammals, with the exception of the procellariiforms, which, strictly speaking, are not true divers.

To investigate thermoregulatory adjustments at sea, body temperatures (the pectoral muscle and the brood patch) and diving behavior were monitored during a foraging trip of several days at sea in six breeding king penguins Aptenodytes patagonicus. During inactive phases at sea (water temperature: 4-7 degrees C), all tissues measured were maintained at normothermic temperatures. The brood patch temperature was maintained at the same values as those measured when brooding on shore (38 degrees C). This high temperature difference causes a significant loss of heat. We hypothesize that high energy expenditure associated with elevated peripheral temperature when resting at sea is the thermoregulatory cost that a post-absorptive penguin has to face for the restoration of its subcutaneous body fat. During diving, mean pectoral temperature was 37.6 +/- 1.6 degrees C. While being almost normothermic on average, the temperature of the pectoral muscle was still significantly lower than during inactivity in five out of the six birds, and underwent temperature drops of up to 5.5 degrees C. Mean brood patch temperature was 29.6 +/- 2.5 degrees C during diving and temperature decreases of up to 21.6 degrees C were recorded. Interestingly, we observed episodes of brood patch warming during the descent to depth suggesting that in some cases, king penguins may perform active thermolysis. It is hypothesized that functional pectoral temperature may be regulated through peripheral adjustments in blood perfusion. These two paradoxical features, i.e. lower temperature of deep tissues during activity, and normothermic peripheral tissues while inactive, may highlight the key to the energetics of this diving endotherm while foraging at sea.

Studying energetics of marine top predators is essential to understand their role within food-webs and mechanisms associated with their survival and population dynamics. Several methods exist to estimate energy expenditure in captive and free-ranging animals. However, most of them are difficult to implement, restrained to specific periods, and are consequently inappropriate for seabirds. Supplementary and complementary approaches are therefore needed, and the use of modelling appears as an excellent option allowing energetic studies when field data collection is challenging. Currently three main energetics models are used, with various degrees of complexity and accuracy: allometric equations, time-energy-budget analyses and thermodynamic models. However, a comparison of their practicability and accuracy was still lacking. Here, we present an overview of these 3 model types, their characteristics, advantages and disadvantages, and areas of application in seabirds. We then investigate their accuracy by using them in parallel for the same dataset, and by comparing outputs with direct measurements (doubly-labelled water technique). We show that, when detailed data are available, time-energy-budget analysis is the best model to accurately predict seabird energy expenditures. Conversely, thermodynamic modelling allows reasonably accurate calculations when field data are scarce, and is therefore ideal to study energetics during the inter-breeding season.

No-take zones may protect populations of targeted marine species and restore the integrity of marine ecosystems, but it is unclear whether they benefit top predators that rely on mobile pelagic fishes. In South Africa, foraging effort of breeding African penguins decreased by 30 per cent within three months of closing a 20 km zone to the competing purse-seine fisheries around their largest colony. After the fishing ban, most of the penguins from this island had shifted their feeding effort inside the closed area. Birds breeding at another colony situated 50 km away, whose fishing grounds remained open to fishing, increased their foraging effort during the same period. This demonstrates the immediate benefit of a relatively small no-take zone for a marine top predator relying on pelagic prey. Selecting such small protected areas may be an important first conservation step, minimizing stakeholder conflicts and easing compliance, while ensuring benefit for the ecosystems within these habitats.

This study aimed to compare physiological and perceptual responses to Nordic walking (NW) in obese women to those of walking (W), and to assess if these responses were modified by a learning period of NW technique. Eleven middle-aged obese women completed exercise trials (5 min each) at 4 km/h, inclinations of -5, 0 and +5%, with and without poles. Ventilation [Formula: see text] oxygen consumption [Formula: see text] energy cost (EC), heart rate (HR), rating of perceived exertion (RPE) and cycle length were measured before and after a 4-week learning period (12 sessions).[Formula: see text] EC, HR and cycle length were significantly higher (P < 0.001) during NW trials than W trials. RPE was significantly diminished (pole x inclination interaction, P = 0.031) when using NW poles compared to W uphill. Significant pole x inclination interactions were observed for [Formula: see text](P = 0.022) and EC (P = 0.022), whereas significant pole x time interaction was found for EC (P = 0.043) and RPE (P = 0.039). Our results confirmed that use of NW poles increased physiological responses at a given speed but decreased RPE in comparison with W during inclined level. Moreover, this is the first study showing that a learning period of NW technique permitted to enhance the difference between EC with NW poles versus the W condition and to decrease the RPE when using NW poles. Thus, although it requires a specific learning of the technique, the NW might be considered like an attractive physical activity with an important public health application.

Heart rate (f(H)) measurement offers the possibility to monitor energy expenditure (EE) in wild animals if the EE/f(H) relationship for the species, physiological stages and activities of interest is known. This relationship has been extensively studied using oxygen consumption rate () measurement in captive, repeatedly handled king penguins (Aptenodytes patagonicus). Unfortunately, the potential effects of stress on the observed relationships resulting from handling and confinement were not considered. This study is the first involving undisturbed animals, and determines the EE/f(H) relationship in naturally fasting and freely incubating or captivity-acclimatized male and female king penguins. EE determination was based on (1) the measurement of body mass loss during periods of phase II fasting, and (2) the calculation of its energy equivalent from changes in body composition, i.e. 23.9 kJ g(-1). f(H) levels in freely incubating and captivity-acclimatized birds were found to be 50-70% lower than those previously reported for resting king penguins during measurements. Significant EE/f(H) relationships were found in freely incubating and captive males and females (R(2)=0.59 to 0.84), with no difference observed between genders. The best overall relationship was obtained by including fasting duration (t, days) in the model: EE=818+43.7xf(H)+36.3t-1.4txf(H)(R(2)=0.91). This equation yielded EE estimates approximately 26% higher than the previously reported 'best' predictive equation in king penguins, and even more so when f(H) was low. This result suggests that stress induces a disproportionate increase of f(H) vs O(2) consumption, and that the use of EE/f(H) relationships obtained in stressed birds could lead to underestimated EE values.

In search of an alternative production route of the therapeutically and environmentally interesting radionuclide (191)Pt (T(1/2)=2.8d), excitation function of the (192)Os((3)He,4n)(191)Pt reaction was measured from its threshold up to 36MeV. Thin samples of enriched (192)Os were prepared by electrodeposition on Ni-foils, and the conventional stacked-foil technique was used for cross-section measurements. The experimental data were compared with the results of theoretical calculations using the codes ALICE-IPPE and TALYS. Good agreement was found with TALYS. The theoretical thick target yield of (191)Pt over the energy range [Formula: see text] amounts to 6.7MBq/muAh. A comparison of various investigated production methods of (191)Pt is given. The here investigated (192)Os((3)He,4n)-process leads to very high-purity (191)Pt (>99.5%).

Abstract Accurate estimates of penguin energetics would represent an important contribution to our understanding of the trophodynamics of the Southern Ocean ecosystem and our ability to predict effects of environmental change on these species. We used the heart rate-rate of oxygen consumption technique to estimate rate of energy expenditure in adult king penguins raising a chick, in combination with data from the literature on changes in adult mass, chick energy requirements, and prey energy density. Our model estimated a variety of energetic costs and quantities of prey consumption related to raising a king penguin chick during the austral summer. The total energy requirements of a king penguin chick at the Crozet Archipelago from hatching until reaching a mass of 8 kg 90 d later is 271 MJ, representing the consumption of 38.4 kg of myctophid fish. A successfully breeding male requires 0.78 kg d(-1) of fish during the entirety of the incubation period and 1.14 kg d(-1) during the subsequent 90 d of chick rearing. Assuming the same energy requirements for females, the estimated 580,000 pairs of king penguins that breed successfully at Crozet each year, together with their chicks, consume a total of around 190,000 tons of fish during the incubation and summer rearing periods combined. If, due to depletion of fish stocks, the diet of breeders and chicks during the summer becomes identical to the typical diet of adults during the austral winter, the mass of prey required by both adults and chicks combined (where the chick still reaches 8 kg after 90 d) would increase by more than 25%.

The ability to measure the energy expenditure of free-ranging animals is of great importance but the techniques available each have their limitations. Recently, as an alternative to more established techniques, an integrated measure of body acceleration termed overall dynamic body acceleration (ODBA) has been used as a calibrated proxy for rate of oxygen consumption (V(O(2))) and hence metabolic rate. The present study tested the potential of this technique, firstly by expanding the range of species for which the V(O(2))-ODBA relationship has been defined and secondly by undertaking a validation exercise to explore the accuracy of predictions made using ODBA. V(O(2))-ODBA relationships during terrestrial locomotion were established for several bipedal and quadrupedal endotherms and compiled with similar relationships previously determined in other species. A model incorporating all of these species showed that ODBA is an excellent predictor of V(O(2)) but there is variation in the V(O(2))-ODBA relationship between species, and further variation within some species. Including measurements such as body mass and structural size in prediction equations might further improve the predictive power of the 'ODBA technique' and eliminate species-specific differences. In the validation exercise, estimate errors were calculated for the species-specific predictive equations. The use of ODBA to estimate V(O(2)) was valid across all species examined and may show a greater potential for estimating energy expenditure for individual animals than other techniques.

Seabirds are sensitive indicators of changes in marine ecosystems and might integrate and/or amplify the effects of climate forcing on lower levels in food chains. Current knowledge on the impact of climate changes on penguins is primarily based on Antarctic birds identified by using flipper bands. Although flipper bands have helped to answer many questions about penguin biology, they were shown in some penguin species to have a detrimental effect. Here, we present for a Subantarctic species, king penguin (Aptenodytes patagonicus), reliable results on the effect of climate on survival and breeding based on unbanded birds but instead marked by subcutaneous electronic tags. We show that warm events negatively affect both breeding success and adult survival of this seabird. However, the observed effect is complex because it affects penguins at several spatio/temporal levels. Breeding reveals an immediate response to forcing during warm phases of El Niño Southern Oscillation affecting food availability close to the colony. Conversely, adult survival decreases with a remote sea-surface temperature forcing (i.e., a 2-year lag warming taking place at the northern boundary of pack ice, their winter foraging place). We suggest that this time lag may be explained by the delay between the recruitment and abundance of their prey, adjusted to the particular 1-year breeding cycle of the king penguin. The derived population dynamic model suggests a 9% decline in adult survival for a 0.26 degrees C warming. Our findings suggest that king penguin populations are at heavy extinction risk under the current global warming predictions.

The "heart rate technique" is commonly used to estimate the rate of oxygen consumption (a proxy for energy expenditure) of free-ranging animals. However, a major limitation of this technique is that interindividual variability in the relationship between heart rate (f(H)) and rate of oxygen consumption (V dot o2) generates large errors of estimation when the technique is applied to individual free-ranging animals. In this study, we present a new analysis technique that takes advantage of the observation that the f(H)/V dot o2 relationships between individuals are frequently parallel and differ only in elevation. This technique offers superior accuracy and precision of V dot o2 estimates, reducing the coefficient of variability from 18% to 9% for individual animals in an example application in macaroni penguins. This approach enables application of the heart rate technique to deduce the energetic strategies of individual animals.

PURPOSE:: This study evaluated the predictive validity of three previously published ActiGraph energy expenditure (EE) prediction equations developed for children and adolescents. METHODS:: A total of 45 healthy children and adolescents (mean age: 13.7 +/- 2.6 yr) completed four 5-min activity trials (normal walking, brisk walking, easy running, and fast running) in an indoor exercise facility. During each trial, participants wore an ActiGraph accelerometer on the right hip. EE was monitored breath by breath using the Cosmed K4b portable indirect calorimetry system. Differences and associations between measured and predicted EE were assessed using dependent t-tests and Pearson correlations, respectively. Classification accuracy was assessed using percent agreement, sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve. RESULTS:: None of the equations accurately predicted mean energy expenditure during each of the four activity trials. Each equation, however, accurately predicted mean EE in at least one activity trial. The Puyau equation accurately predicted EE during slow walking. The Trost equation accurately predicted EE during slow running. The Freedson equation accurately predicted EE during fast running. None of the three equations accurately predicted EE during brisk walking. The equations exhibited fair to excellent classification accuracy with respect to activity intensity, with the Trost equation exhibiting the highest classification accuracy and the Puyau equation exhibiting the lowest. CONCLUSIONS:: These data suggest that the three accelerometer prediction equations do not accurately predict EE on a minute-by-minute basis in children and adolescents during overground walking and running. The equations maybe useful, however, for estimating participation in moderate and vigorous activity.