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G L Kooyman - One of the best experts on this subject based on the ideXlab platform.
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Too much of a good thing: sea ice extent may have forced emperor penguins into refugia during the last glacial maximum.
Global change biology, 2015Co-Authors: Jane L. Younger, G L Kooyman, Barbara Wienecke, Alex Rogers, Gemma V. Clucas, Philip N. Trathan, Tom Hart, Karen J. MillerAbstract:The relationship between population structure and demographic history is critical to understanding microevolution and for predicting the resilience of species to environmental change. Using mitochondrial DNA from extant colonies and radiocarbon-dated subfossils, we present the first microevolutionary analysis of emperor penguins (Aptenodytes Forsteri) and show their population trends throughout the last glacial maximum (LGM, 19.5–16 kya) and during the subsequent period of warming and sea ice retreat. We found evidence for three mitochondrial clades within emperor penguins, suggesting that they were isolated within three glacial refugia during the LGM. One of these clades has remained largely isolated within the Ross Sea, while the two other clades have intermixed around the coast of Antarctica from Adelie Land to the Weddell Sea. The differentiation of the Ross Sea population has been preserved despite rapid population growth and opportunities for migration. Low effective population sizes during the LGM, followed by a rapid expansion around the beginning of the Holocene, suggest that an optimum set of sea ice conditions exist for emperor penguins, corresponding to available foraging area.
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Stroke rates and diving air volumes of emperor penguins: implications for dive performance.
Journal of Experimental Biology, 2011Co-Authors: Katsufumi Sato, G L Kooyman, Kozue Shiomi, Greg Marshall, Paul J PonganisAbstract:Emperor penguins (Aptenodytes Forsteri), both at sea and at an experimental dive hole, often have minimal surface periods even after performance of dives far beyond their measured 5.6 min aerobic dive limit (ADL: dive duration associated with the onset of post-dive blood lactate accumulation). Accelerometer-based data loggers were attached to emperor penguins diving in these two different situations to further evaluate the capacity of these birds to perform such dives without any apparent prolonged recovery periods. Minimum surface intervals for dives as long as 10 min were less than 1 min at both sites. Stroke rates for dives at sea were significantly greater than those for dives at the isolated dive hole. Calculated diving air volumes at sea were variable, increased with maximum depth of dive to a depth of 250 m, and decreased for deeper dives. It is hypothesized that lower air volumes for the deepest dives are the result of exhalation of air underwater. Mean maximal air volumes for deep dives at sea were approximately 83% greater than those during shallow (
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Estimating the relative abundance of emperor penguins at inaccessible colonies using satellite imagery
Polar Biology, 2007Co-Authors: Shannon M. Barber-meyer, G L Kooyman, Paul J PonganisAbstract:Emperor penguin ( Aptenodytes Forsteri ) populations are useful environmental indicators due to the bird’s extreme reliance on sea ice. We used remote sensing technology to estimate relative adult bird abundance at two inaccessible emperor penguin colonies in the Ross Sea, Antarctica. We performed supervised classification of 12 panchromatic satellite images of the seven known Ross Sea colonies. We used regression to predict adult bird counts at the inaccessible colonies by relating the number of pixels classified as “penguin” in the satellite images of the accessible colonies to corresponding known adult bird counts from aerial photographs or ground counts. While our analysis was hampered by excessive guano and shadows, we used satellite imagery to differentiate between relatively small (5,000 adult birds). Remote sensing technology is logistically less intense and less costly than aerial or ground censuses when the objective is to document penguin presence and/or large emperor penguin population changes (e.g., catastrophic changes). Improvements expected soon in the resolution of the satellite images should allow for more accurate abundance estimates.
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Energetic cost of foraging in free-diving emperor penguins.
Physiological and biochemical zoology : PBZ, 2001Co-Authors: Kenneth A. Nagy, G L Kooyman, Paul J PonganisAbstract:Abstract Hypothesizing that emperor penguins (Aptenodytes Forsteri) would have higher daily energy expenditures when foraging for their food than when being hand‐fed and that the increased expenditure could represent their foraging cost, we measured field metabolic rates (FMR; using doubly labeled water) over 4‐d periods when 10 penguins either foraged under sea ice or were not allowed to dive but were fed fish by hand. Surprisingly, penguins did not have higher rates of energy expenditure when they dove and captured their own food than when they did not forage but were given food. Analysis of time‐activity and energy budgets indicated that FMR was about \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \...
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Food of emperor penguins (Aptenodytes Forsteri ) in the western Ross Sea, Antarctica
Marine Biology, 1998Co-Authors: Yves Cherel, G L KooymanAbstract:The diet of the emperor penguin Aptenodytes Forsteri in the western Ross Sea during spring was investigated by analysis of stomach contents sampled at three different localities. At Cape Washington, emperor penguins feeding chicks consistently preyed on fishes (89 to 95% by mass) and crustaceans (5 to 11%) over the four spring seasons examined. By far the commonest prey was the Antarctic silverfish Pleuragramma antarcticum (89% of the fish prey); the remainder of fish prey were mainly unidentified juveniles of different species of channichthyid fishes. Three species dominated the crustacean part of the diet, i.e. the gammarid amphipods Abyssorchomene rossi/plebs (30% of the crustacean prey) and Eusirus microps (22%), together with the euphausiid Euphausia crystallorophias (24%). At Coulman Island and Cape Roget, fishes, mainly P. antarcticum, formed the bulk of the food (88 and 93% by mass, respectively), crustaceans were minor prey (2.5 and 0.4%), and the squid Psychroteuthis glacialis accounted for a small but significant part of the food (3.5 and 0.8%). This study emphasizes the importance of the small, shoaling pelagic fish Pleuragramma antarcticum as a key link between zooplankton and top predators, including seabirds, in the food web and marine ecosystem of the Ross Sea.
Barbara Wienecke - One of the best experts on this subject based on the ideXlab platform.
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Comparative population genomics reveals key barriers to dispersal in Southern Ocean penguins.
Molecular ecology, 2018Co-Authors: Gemma V. Clucas, Barbara Wienecke, Damian Kao, Louise Emmerson, Colin Southwell, Alex Rogers, Charles-andré Bost, Gary Miller, Jane L. Younger, Michael J. PolitoAbstract:The mechanisms that determine patterns of species dispersal are important factors in the production and maintenance of biodiversity. Understanding these mechanisms helps to forecast the responses of species to environmental change. Here, we used a comparative framework and genomewide data obtained through RAD-Seq to compare the patterns of connectivity among breeding colonies for five penguin species with shared ancestry, overlapping distributions and differing ecological niches, allowing an examination of the intrinsic and extrinsic barriers governing dispersal patterns. Our findings show that at-sea range and oceanography underlie patterns of dispersal in these penguins. The pelagic niche of emperor (Aptenodytes Forsteri), king (A. patagonicus), Adelie (Pygoscelis adeliae) and chinstrap (P. antarctica) penguins facilitates gene flow over thousands of kilometres. In contrast, the coastal niche of gentoo penguins (P. papua) limits dispersal, resulting in population divergences. Oceanographic fronts also act as dispersal barriers to some extent. We recommend that forecasts of extinction risk incorporate dispersal and that management units are defined by at-sea range and oceanography in species lacking genetic data.
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Comparative population genomics reveals key barriers to dispersal in Southern Ocean penguins
Molecular Ecology, 2018Co-Authors: Gemma Clucas, Barbara Wienecke, Jane Younger, Damian Kao, Louise Emmerson, Colin Southwell, Alex Rogers, Charles-andré Bost, Gary Miller, Michael PolitoAbstract:The mechanisms that determine patterns of species dispersal are important factors in the production and maintenance of biodiversity. Understanding these mechanisms helps to forecast the responses of species to environmental change. Here, we used a comparative framework and genomewide data obtained through RAD‐Seq to compare the patterns of connectivity among breeding colonies for five penguin species with shared ancestry, overlapping distributions and differing ecological niches, allowing an examination of the intrinsic and extrinsic barriers governing dispersal patterns. Our findings show that at‐sea range and oceanography underlie patterns of dispersal in these penguins. The pelagic niche of emperor (Aptenodytes Forsteri), king (A. patagonicus), Adélie (Pygoscelis adeliae) and chinstrap (P. antarctica) penguins facilitates gene flow over thousands of kilometres. In contrast, the coastal niche of gentoo penguins (P. papua) limits dispersal, resulting in population divergences. Oceanographic fronts also act as dispersal barriers to some extent. We recommend that forecasts of extinction risk incorporate dispersal and that management units are defined by at‐sea range and oceanography in species lacking genetic data.
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Coordinated movements prevent jamming in an Emperor penguin huddle. PloS one. 2011 Jan; 6(6):e20260. Available from: http://www.pubmedcentral. nih.gov/articlerender.fcgi?artid=3106014&tool=pmcentrez&rendertype=abstract doi: 10.1371/journal. p
2016Co-Authors: Daniel P. Zitterbart, Barbara Wienecke, James P. Butler, Ben FabryAbstract:For Emperor penguins (Aptenodytes Forsteri), huddling is the key to survival during the Antarctic winter. Penguins in a huddle are packed so tightly that individual movements become impossible, reminiscent of a jamming transition in compacted colloids. It is crucial, however, that the huddle structure is continuously reorganized to give each penguin a chance to spend sufficient time inside the huddle, compared with time spent on the periphery. Here we show that Emperor penguins move collectively in a highly coordinated manner to ensure mobility while at the same time keeping the huddle packed. Every 30–60 seconds, all penguins make small steps that travel as a wave through the entire huddle. Over time, these small movements lead to large-scale reorganization of the huddle. Our data show that the dynamics of penguin huddling is governed by intermittency and approach to kinetic arrest in striking analogy with inert non-equilibrium systems, including soft glasses and colloids
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Too much of a good thing: sea ice extent may have forced emperor penguins into refugia during the last glacial maximum.
Global change biology, 2015Co-Authors: Jane L. Younger, G L Kooyman, Barbara Wienecke, Alex Rogers, Gemma V. Clucas, Philip N. Trathan, Tom Hart, Karen J. MillerAbstract:The relationship between population structure and demographic history is critical to understanding microevolution and for predicting the resilience of species to environmental change. Using mitochondrial DNA from extant colonies and radiocarbon-dated subfossils, we present the first microevolutionary analysis of emperor penguins (Aptenodytes Forsteri) and show their population trends throughout the last glacial maximum (LGM, 19.5–16 kya) and during the subsequent period of warming and sea ice retreat. We found evidence for three mitochondrial clades within emperor penguins, suggesting that they were isolated within three glacial refugia during the LGM. One of these clades has remained largely isolated within the Ross Sea, while the two other clades have intermixed around the coast of Antarctica from Adelie Land to the Weddell Sea. The differentiation of the Ross Sea population has been preserved despite rapid population growth and opportunities for migration. Low effective population sizes during the LGM, followed by a rapid expansion around the beginning of the Holocene, suggest that an optimum set of sea ice conditions exist for emperor penguins, corresponding to available foraging area.
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Emperor penguins at the West Ice Shelf
Polar Biology, 2012Co-Authors: Barbara WieneckeAbstract:In 1956, an emperor penguin ( Aptenodytes Forsteri ) colony had been reported during an aerial survey north of the north-western protrusion of the West Ice Shelf in East Antarctica. About 15,000 birds were estimated to be present. The region often has very heavy pack ice conditions hindering access by vessels. In the summers of 2009–2011, we surveyed the area from the air and sighted two emperor penguin colonies. One was situated on top of the ice shelf and comprised 342 adults and 1,156 chicks. The second colony was seen near the northern edge of the West Ice Shelf on the sea ice about 60 km farther south than in 1956. There were at least 1,498 adults and 3,436 chicks.
Paul J Ponganis - One of the best experts on this subject based on the ideXlab platform.
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Full circumpolar migration ensures evolutionary unity in the Emperor penguin
Nature Communications, 2016Co-Authors: Robin Cristofari, Paul J Ponganis, Yvon Le Maho, André Ancel, Giorgio Bertorelle, Andrea Benazzo, Nils Chr Stenseth, Phil N. Trathan, Jason D. Whittington, Enrico ZanettiAbstract:Defining reliable demographic models is essential to understand the threats of ongoing environmental change. Yet, in the most remote and threatened areas, models are often based on the survey of a single population, assuming stationarity and independence in population responses. This is the case for the Emperor penguin Aptenodytes Forsteri, a flagship Antarctic species that may be at high risk continent-wide before 2100. Here, using genome-wide data from the whole Antarctic continent, we reveal that this top-predator is organized as one single global population with a shared demography since the late Quaternary. We refute the view of the local population as a relevant demographic unit, and highlight that (i) robust extinction risk estimations are only possible by including dispersal rates and (ii) colony-scaled population size is rather indicative of local stochastic events, whereas the species’ response to global environmental change is likely to follow a shared evolutionary trajectory.
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Muscle Oxygen Saturation Measurements in Diving Mammals and Birds Using NIRS
Application of Near Infrared Spectroscopy in Biomedicine, 2013Co-Authors: Cassondra L. Williams, Paul J PonganisAbstract:Near-infrared spectroscopy (NIRS) principles have been applied to study muscle oxygen (O2) saturation in diving mammals and birds. Custom-made NIRS instruments and probes were developed to measure myoglobin (Mb) O2 saturation levels in two studies conducted in Antarctica at isolated dive holes on the sea ice of McMurdo Sound on freely-diving Weddell seals (Leptonychotes weddellii) and on freely diving emperor penguins (Aptenodytes Forsteri). Studies also used a modified, commercially available NIRS instrument (Vander Niroscope) to measure muscle O2 levels in trained harbor seals for simulated dives using a helmet that filled with water for specific time periods. The present chapter will focus on NIRS principles and the development and application of custom-made instruments and the methodology to study diving mammals.
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In pursuit of Irving and Scholander: a review of oxygen store management in seals and penguins
Journal of Experimental Biology, 2011Co-Authors: Paul J Ponganis, Jessica U. Meir, Cassondra L. WilliamsAbstract:Since the introduction of the aerobic dive limit (ADL) 30 years ago, the concept that most dives of marine mammals and sea birds are aerobic in nature has dominated the interpretation of their diving behavior and foraging ecology. Although there have been many measurements of body oxygen stores, there have been few investigations of the actual depletion of those stores during dives. Yet, it is the pattern, rate and magnitude of depletion of O(2) stores that underlie the ADL. Therefore, in order to assess strategies of O(2) store management, we review (a) the magnitude of O(2) stores, (b) past studies of O(2) store depletion and (c) our recent investigations of O(2) store utilization during sleep apnea and dives of elephant seals (Mirounga angustirostris) and during dives of emperor penguins (Aptenodytes Forsteri). We conclude with the implications of these findings for (a) the physiological responses underlying O(2) store utilization, (b) the physiological basis of the ADL and (c) the value of extreme hypoxemic tolerance and the significance of the avoidance of re-perfusion injury in these animals.
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Stroke rates and diving air volumes of emperor penguins: implications for dive performance.
Journal of Experimental Biology, 2011Co-Authors: Katsufumi Sato, G L Kooyman, Kozue Shiomi, Greg Marshall, Paul J PonganisAbstract:Emperor penguins (Aptenodytes Forsteri), both at sea and at an experimental dive hole, often have minimal surface periods even after performance of dives far beyond their measured 5.6 min aerobic dive limit (ADL: dive duration associated with the onset of post-dive blood lactate accumulation). Accelerometer-based data loggers were attached to emperor penguins diving in these two different situations to further evaluate the capacity of these birds to perform such dives without any apparent prolonged recovery periods. Minimum surface intervals for dives as long as 10 min were less than 1 min at both sites. Stroke rates for dives at sea were significantly greater than those for dives at the isolated dive hole. Calculated diving air volumes at sea were variable, increased with maximum depth of dive to a depth of 250 m, and decreased for deeper dives. It is hypothesized that lower air volumes for the deepest dives are the result of exhalation of air underwater. Mean maximal air volumes for deep dives at sea were approximately 83% greater than those during shallow (
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Estimating the relative abundance of emperor penguins at inaccessible colonies using satellite imagery
Polar Biology, 2007Co-Authors: Shannon M. Barber-meyer, G L Kooyman, Paul J PonganisAbstract:Emperor penguin ( Aptenodytes Forsteri ) populations are useful environmental indicators due to the bird’s extreme reliance on sea ice. We used remote sensing technology to estimate relative adult bird abundance at two inaccessible emperor penguin colonies in the Ross Sea, Antarctica. We performed supervised classification of 12 panchromatic satellite images of the seven known Ross Sea colonies. We used regression to predict adult bird counts at the inaccessible colonies by relating the number of pixels classified as “penguin” in the satellite images of the accessible colonies to corresponding known adult bird counts from aerial photographs or ground counts. While our analysis was hampered by excessive guano and shadows, we used satellite imagery to differentiate between relatively small (5,000 adult birds). Remote sensing technology is logistically less intense and less costly than aerial or ground censuses when the objective is to document penguin presence and/or large emperor penguin population changes (e.g., catastrophic changes). Improvements expected soon in the resolution of the satellite images should allow for more accurate abundance estimates.
Graham Robertson - One of the best experts on this subject based on the ideXlab platform.
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Maiden journey of fledgling emperor penguins from the Mawson Coast, East Antarctica
Marine Ecology Progress Series, 2010Co-Authors: Barbara Wienecke, Ben Raymond, Graham RobertsonAbstract:The at-sea distribution of fledgling emperor penguins Aptenodytes Forsteri is largely unknown. Seven and 10 fledglings, respectively, were satellite tracked on their maiden voyage from the colonies at Taylor Glacier in 1996 and from Auster in 2007. In both years, the young birds dispersed widely, well beyond the pack ice zone once they had left and reached open water. They spent a substantial part of their time north of 60° S, i.e. outside the Antarctic Treaty area. The northernmost latitudes reached were 54° 14’ S in 1996 and 56° 15’ S in 2007. Their longitudinal distribution ranged from 7 to 93° E. The fledglings did not congregate in particular feeding areas nor did they appear to be associated with oceanographic fronts or the sea ice in their first 2 to 3 mo at sea. Towards the beginning of winter, they changed course and headed south back towards the ice but not to their natal colonies.
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Extreme dives by free-ranging emperor penguins
Polar Biology, 2007Co-Authors: Barbara Wienecke, Graham Robertson, Roger Kirkwood, Kieran LawtonAbstract:We examined the incidence of extreme diving in a 3-year overwintering study of emperor penguins Aptenodytes Forsteri in East Antarctica. We defined extreme dives as very deep (> 400 m) and/or very long (> 12 min). Of 137364 dives recorded by 93 penguins 264 dives reached depths > 400 m and 48 lasted > 12 min. Most (65%) very long dives occurred in winter (May–August) while 83% of the very deep dives took place in spring (September–November). The two most extreme dives (564 m depth, 21.8 min duration) were separate dives and were performed by different individual penguins. Penguins diving extremely deeply may have done so as part of their foraging strategy whereas penguins diving for very long times may have been forced to do so by changes in the sea-ice conditions.
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Pre-moult foraging trips and moult locations of Emperor penguins at the Mawson Coast
Polar Biology, 2004Co-Authors: Barbara Wienecke, Roger Kirkwood, Graham RobertsonAbstract:The movements of nine breeding adult emperor penguins Aptenodytes Forsteri from two colonies, Auster (67° 23′S 64° 04′E) and Taylor Glacier (67° 28′S 60° 54′E), were determined by satellite telemetry on their pre-moult foraging trips. While preparing for their annual moult the penguins travelled for 22–38 days and reached distances of up to 618 km from the colony. Six of the nine tracked penguins were followed to three different moult locations all to the west of their breeding colonies and near other known emperor penguins colonies, such as Kloa Point (66°38′S, 59°23′E) and Fold Island (67°17′S, 59°23′E). Sea-ice conditions changed throughout the tracking period; as the birds travelled north the sea-ice contracted south.
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The Occurrence and Purpose of Huddling by Emperor Penguins During Foraging Trips
Emu - Austral Ornithology, 1999Co-Authors: Roger Kirkwood, Graham RobertsonAbstract:Between May and October 1993, temperature/light recorders mounted on the backs of Emperor Penguins Aptenodytes Forsteri on foraging trips recorded occasions when light intensities were consistent w...
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Foraging space of emperor penguins Aptenodytes Forsteri in Antarctic shelf waters in winter
Marine Ecology Progress Series, 1997Co-Authors: Barbara Wienecke, Graham RobertsonAbstract:To determine the foraging space of emperor penguins Aptenodytes Forsteri in winter, 12 females from Auster colony (13400 pairs) were equipped with satellite transmitters and time-depth recorders before departing on their 76 * 9 d winter (June to August) foraging trip. The females were also injected with tritiated water (HTO) to estimate food consumption, and non-instrumented females were stomach sampled upon return to the colony to determine their diet. The same data were collected in August/September from 3 males foraging after their 4 mo prenuptial and incubation fast. Both females and males foraged in pack-ice within 120 km of the colony along a relatively narrow band of the continental shelf in water depths ranging from 200 to 500 m. Only rarely did penguins leave shelf waters to forage in deeper waters over the shelf break. The size of the general foraging area for females was about 11 410 km2, but 50% of all foraging days were spent in only about 15% (1700 km2) of the total foraging area. A female of average mass (25 kg) hunted for about 6 h d-l, and consumed 1.8 * 0.3 kg of food per foraging day. This indicates that females from Auster consumed in winter about 1520 t, about half of which is likely to have been taken from an area measuring only 60 X 28 km. Males were active for about 10 h d ' and consumed about twice as much (3.7 * 7.2 kg d-I for a 24 kg male) as the females during the early phase of brooding. The diet of females comprised 72% fish (by mass). 16% squid and 12% Antarctic krill Euphausia superba whereas that of the males comprised 53% fish. 2U/o squid and 43% krill. Most foraging dives of females (81 %) and males (64 %) were to 300 m) more frequently than females (19.8% vs 0.1 %) but the number of dives per day was similar for both sexes (27 + 14 for winter females, 31 i 15 for brood-stage males). The small foraging area, diet composition and prey harvest rates of the females provide indirect evidence of the availability of penguin prey species in the pack-ice off Auster in winter.
Phil O'b. Lyver - One of the best experts on this subject based on the ideXlab platform.
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Latitudinal, sex and inter-specific differences in mercury and other trace metal concentrations in Adélie and Emperor penguins in the Ross Sea, Antarctica.
Marine pollution bulletin, 2020Co-Authors: Natalie Pilcher, Sally Gaw, Regina Eisert, Travis W. Horton, Andrew M. Gormley, Theresa L. Cole, Phil O'b. LyverAbstract:Abstract We sought to determine mercury (Hg) and other trace metal concentrations in Adelie (Pygoscelis adeliae) and emperor penguin (Aptenodytes Forsteri) breast feathers from the Ross Sea, Antarctica, and relate those concentrations to the trophic position and the habitats in which each of these species forage. Adelie penguin feathers from the southern Ross Sea colonies were higher in Hg than those sampled further north in the Ross Sea, potentially due to greater exposure to local sources, such as volcanism. Female Adelie penguins had lower feather total Hg concentrations than males. This may reflect female penguin's capacity to eliminate Hg through the egg development and laying process, or the larger and/or older prey items that male birds can consume, reflected by their higher trophic position. Emperor penguins have higher Hg concentrations than Adelie penguins which is also partially explained by Adelie penguins feeding at lower trophic levels than emperor penguins.