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Ponganis PJ, Williams CL, Kendall-Bar JM. Blood oxygen transport and depletion in diving emperor penguins. J Exp Biol 2024; 227:jeb246832. [PMID: 38390686 PMCID: PMC11006389 DOI: 10.1242/jeb.246832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/06/2024] [Indexed: 02/24/2024]
Abstract
Oxygen store management underlies dive performance and is dependent on the slow heart rate and peripheral vasoconstriction of the dive response to control tissue blood flow and oxygen uptake. Prior research has revealed two major patterns of muscle myoglobin saturation profiles during dives of emperor penguins. In Type A profiles, myoglobin desaturated rapidly, consistent with minimal muscle blood flow and low tissue oxygen uptake. Type B profiles, with fluctuating and slower declines in myoglobin saturation, were consistent with variable tissue blood flow patterns and tissue oxygen uptake during dives. We examined arterial and venous blood oxygen profiles to evaluate blood oxygen extraction and found two primary patterns of venous hemoglobin desaturation that complemented corresponding myoglobin saturation profiles. Type A venous profiles had a hemoglobin saturation that (a) increased/plateaued for most of a dive's duration, (b) only declined during the latter stages of ascent, and (c) often became arterialized [arterio-venous (a-v) shunting]. In Type B venous profiles, variable but progressive hemoglobin desaturation profiles were interrupted by inflections in the profile that were consistent with fluctuating tissue blood flow and oxygen uptake. End-of-dive saturation of arterial and Type A venous hemoglobin saturation profiles were not significantly different, but did differ from those of Type B venous profiles. These findings provide further support that the dive response of emperor penguins is a spectrum of cardiac and vascular components (including a-v shunting) that are dependent on the nature and demands of a given dive and even of a given segment of a dive.
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Affiliation(s)
- Paul J. Ponganis
- Center for Marine Biotechnology & Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
| | - Cassondra L. Williams
- National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, CA 92106, USA
| | - Jessica M. Kendall-Bar
- Center for Marine Biotechnology & Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
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2
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Saito A, Kinoshita C, Sakai K, Sato K, Sakamoto KQ. Heart rate reduction during voluntary deep diving in free-ranging loggerhead sea turtles. J Exp Biol 2024; 227:jeb246334. [PMID: 38442390 PMCID: PMC10949068 DOI: 10.1242/jeb.246334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 01/23/2024] [Indexed: 03/07/2024]
Abstract
Air-breathing vertebrates exhibit cardiovascular responses to diving including heart rate reduction (diving bradycardia). Field studies on aquatic mammals and birds have shown that the intensity of bradycardia can vary depending on diving behaviour, such as the depth of dives and dive duration. However, in aquatic reptiles, the variation in heart rate during deep dives under natural conditions has not been fully investigated. In this study, we released five loggerhead sea turtles (Caretta caretta) outfitted with recorders into the sea and recorded their electrocardiogram, depth, water temperature and longitudinal acceleration. After 3 days, the recorders automatically detached from the turtles. The heart rate signals were detected from the electrodes placed on the surface of the plastron. The mean (±s.d.) heart rate of 12.8±4.1 beats min-1 during dives was significantly lower than that of 20.9±4.1 beats min-1 during surface periods. Heart rate during dives varied with dive depth, although it remained lower than that at the surface. When the turtle dived deeper than 140 m, despite the relatively high flipper stroke rate (approximately 19 strokes min-1), the heart rate dropped rapidly to approximately 2 beats min-1 temporarily. The minimum instantaneous heart rate during dives was lower at deeper dive depths. Our results indicate that loggerhead sea turtles show variations in the intensity of diving bradycardia depending on their diving behaviour, similar to that shown by marine mammals and birds.
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Affiliation(s)
- Ayaka Saito
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Chihiro Kinoshita
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Kino Sakai
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Katsufumi Sato
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Kentaro Q. Sakamoto
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
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3
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Cole MR, Ware C, McHuron EA, Costa DP, Ponganis PJ, McDonald BI. Deep dives and high tissue density increase mean dive costs in California sea lions (Zalophus californianus). J Exp Biol 2023; 226:jeb246059. [PMID: 37345474 DOI: 10.1242/jeb.246059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/14/2023] [Indexed: 06/23/2023]
Abstract
Diving is central to the foraging strategies of many marine mammals and seabirds. Still, the effect of dive depth on foraging cost remains elusive because energy expenditure is difficult to measure at fine temporal scales in wild animals. We used depth and acceleration data from eight lactating California sea lions (Zalophus californianus) to model body density and investigate the effect of dive depth and tissue density on rates of energy expenditure. We calculated body density in 5 s intervals from the rate of gliding descent. We modeled body density across depth in each dive, revealing high tissue densities and diving lung volumes (DLVs). DLV increased with dive depth in four individuals. We used the buoyancy calculated from dive-specific body-density models and drag calculated from swim speed to estimate metabolic power and cost of transport in 5 s intervals during descents and ascents. Deeper dives required greater mean power for round-trip vertical transit, especially in individuals with higher tissue density. These trends likely follow from increased mean swim speed and buoyant hinderance that increasingly outweighs buoyant aid in deeper dives. This suggests that deep diving is either a 'high-cost, high-reward' strategy or an energetically expensive option to access prey when prey in shallow waters are limited, and that poor body condition may increase the energetic costs of deep diving. These results add to our mechanistic understanding of how foraging strategy and body condition affect energy expenditure in wild breath-hold divers.
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Affiliation(s)
- Mason R Cole
- Moss Landing Marine Laboratories, San Jose State University, 8272 Moss Landing Rd, Moss Landing, CA 95039, USA
| | - Colin Ware
- Center for Coastal and Ocean Mapping, University of New Hampshire, Durham, NH 03924, USA
| | - Elizabeth A McHuron
- Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA 98105, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
| | - Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
| | - Birgitte I McDonald
- Moss Landing Marine Laboratories, San Jose State University, 8272 Moss Landing Rd, Moss Landing, CA 95039, USA
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Arif S, Massey MDB. Reducing bias in experimental ecology through directed acyclic graphs. Ecol Evol 2023; 13:e9947. [PMID: 37006894 PMCID: PMC10050842 DOI: 10.1002/ece3.9947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/10/2023] [Accepted: 03/12/2023] [Indexed: 03/31/2023] Open
Abstract
Ecologists often rely on randomized control trials (RCTs) to quantify causal relationships in nature. Many of our foundational insights of ecological phenomena can be traced back to well‐designed experiments, and RCTs continue to provide valuable insights today. Although RCTs are often regarded as the “gold standard” for causal inference, it is important to recognize that they too rely on a set of causal assumptions that must be justified and met by the researcher to draw valid causal conclusions. We use key ecological examples to show how biases such as confounding, overcontrol, and collider bias can occur in experimental setups. In tandem, we highlight how such biases can be removed through the application of the structural causal model (SCM) framework. The SCM framework visualizes the causal structure of a system or process under study using directed acyclic graphs (DAGs) and subsequently applies a set of graphical rules to remove bias from both observational and experimental data. We show how DAGs can be applied across ecological experimental studies to ensure proper study design and statistical analysis, leading to more accurate causal estimates drawn from experimental data. Although causal conclusions drawn from RCTs are often taken at face value, ecologists are increasingly becoming aware that experimental approaches must be carefully designed and analyzed to avoid potential biases. By applying DAGs as a visual and conceptual tool, experimental ecologists can increasingly meet the causal assumptions required for valid causal inference.
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Affiliation(s)
- Suchinta Arif
- Department of BiologyDalhousie University1355 Oxford StreetHalifaxNova ScotiaB3H 4R2Canada
| | - Melanie Duc Bo Massey
- Department of BiologyDalhousie University1355 Oxford StreetHalifaxNova ScotiaB3H 4R2Canada
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5
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Saito R, Yamasaki T, Tanaka H. Fluid drag reduction by penguin-mimetic laser-ablated riblets with yaw angles. BIOINSPIRATION & BIOMIMETICS 2022; 17:056010. [PMID: 35797974 DOI: 10.1088/1748-3190/ac7f71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
The bodies of penguins, which swim underwater to forage, are densely covered with feathers, in which the barbs are oriented in the longitudinal direction. We hypothesize that these barbs act as riblets and reduce friction drag during swimming. Considering various real-world swim conditions, the drag reduction effect is expected to be robust against changes in the flow speed and yaw angle relative to the flow. To test this hypothesis, we created trapezoidal riblets based on the morphology of these barbs and measured the drag of flat plates with these fabricated riblets in a water tunnel. The spacing, width, and height of the barbs were found to be approximately 100, 60, and 30 μm, respectively. This spacing resulted in a nondimensional spacings+of 5.5 for a typical penguin swimming speed of 1.4 m s-1. We fabricated four types of riblets on polyimide films by ultraviolet laser ablation. The first was a small-scale riblet for which the spacing was decreased to 41 μm to simulate the surface flow condition of the usual and slower swim behaviors in our water tunnel. The other three were manufactured to the actual scale of real barbs (spacing of 100 μm) with three different rib ridge widths: 10, 25, and 50 μm. Yaw angles of 0°, 15°, 30°, and 45° were also tested with the actual-scale riblets. The drag reduction rate of the small-scale riblet was maximized to 1.97% by the smallests+of 1.59. For all three actual-scale riblets, increasing the yaw angle from zero to 15° enhanced the drag reduction rate for the full range ofs+up to 13.5. The narrow-ridge riblet reduced drag at an even higher yaw angle of 45°, but the drag increased with zero yaw angle. Overall, the medium-ridge riblet, which was representative of the barbs, was well-balanced.
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Affiliation(s)
- Ryosuke Saito
- Department of Mechanical Engineering, School of Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Takeshi Yamasaki
- Yamashina Institute for Ornithology, 115 Konoyama, Abiko, Chiba, 270-1145, Japan
| | - Hiroto Tanaka
- Department of Mechanical Engineering, School of Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
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6
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Nazario EC, Cade DE, Bierlich K, Czapanskiy MF, Goldbogen JA, Kahane-Rapport SR, van der Hoop JM, San Luis MT, Friedlaender AS. Baleen whale inhalation variability revealed using animal-borne video tags. PeerJ 2022; 10:e13724. [PMID: 35880219 PMCID: PMC9308462 DOI: 10.7717/peerj.13724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/22/2022] [Indexed: 01/17/2023] Open
Abstract
Empirical metabolic rate and oxygen consumption estimates for free-ranging whales have been limited to counting respiratory events at the surface. Because these observations were limited and generally viewed from afar, variability in respiratory properties was unknown and oxygen consumption estimates assumed constant breath-to-breath tidal volume and oxygen uptake. However, evidence suggests that cetaceans in human care vary tidal volume and breathing frequency to meet aerobic demand, which would significantly impact energetic estimates if the findings held in free-ranging species. In this study, we used suction cup-attached video tags positioned posterior to the nares of two humpback whales (Megaptera novaeangliae) and four Antarctic minke whales (Balaenoptera bonaerensis) to measure inhalation duration, relative nares expansion, and maximum nares expansion. Inhalation duration and nares expansion varied between and within initial, middle, and terminal breaths of surface sequences between dives. The initial and middle breaths exhibited the least variability and had the shortest durations and smallest nares expansions. In contrast, terminal breaths were highly variable, with the longest inhalation durations and the largest nares expansions. Our results demonstrate breath-to-breath variability in duration and nares expansion, suggesting differential oxygen exchange in each breath during the surface interval. With future validation, inhalation duration or nares area could be used alongside respiratory frequency to improve oxygen consumption estimates by accounting for breath-to-breath variation in wild whales.
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Affiliation(s)
- Emily C. Nazario
- Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, United States of America
| | - David E. Cade
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - K.C. Bierlich
- Marine Mammal Institute, Hatfield Marine Science Center, Oregon State University, Newport, OR, United States of America
| | - Max F. Czapanskiy
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - Jeremy A. Goldbogen
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - Shirel R. Kahane-Rapport
- Department of Biological Science, California State University, Fullerton, Fullerton, CA, United States of America
| | | | - Merceline T. San Luis
- Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, United States of America
| | - Ari S. Friedlaender
- Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA, United States of America
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7
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Czapanskiy MF, Ponganis PJ, Fahlbusch JA, Schmitt TL, Goldbogen JA. An accelerometer-derived ballistocardiogram method for detecting heartrates in free-ranging marine mammals. J Exp Biol 2022; 225:275276. [PMID: 35502794 PMCID: PMC9167577 DOI: 10.1242/jeb.243872] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 04/28/2022] [Indexed: 11/24/2022]
Abstract
Physio-logging methods, which use animal-borne devices to record physiological variables, are entering a new era driven by advances in sensor development. However, existing datasets collected with traditional bio-loggers, such as accelerometers, still contain untapped eco-physiological information. Here, we present a computational method for extracting heart rate from high-resolution accelerometer data using a ballistocardiogram. We validated our method with simultaneous accelerometer–electrocardiogram tag deployments in a controlled setting on a killer whale (Orcinus orca) and demonstrate the predictions correspond with previously observed cardiovascular patterns in a blue whale (Balaenoptera musculus), including the magnitude of apneic bradycardia and increase in heart rate prior to and during ascent. Our ballistocardiogram method may be applied to mine heart rates from previously collected accelerometery data and expand our understanding of comparative cardiovascular physiology. Highlighted Article: Validation of a computational method for extracting heart rate in free-ranging cetaceans from high-resolution accelerometer data using a ballistocardiogram.
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Affiliation(s)
- Max F Czapanskiy
- Hopkins Marine Station, Department of Biology, Stanford University, USA
| | - Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, USA
| | - James A Fahlbusch
- Hopkins Marine Station, Department of Biology, Stanford University, USA
| | - T L Schmitt
- Animal Health Department, SeaWorld of California, USA
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8
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Ponganis PJ. A Physio-Logging Journey: Heart Rates of the Emperor Penguin and Blue Whale. Front Physiol 2021; 12:721381. [PMID: 34413792 PMCID: PMC8369151 DOI: 10.3389/fphys.2021.721381] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/08/2021] [Indexed: 11/23/2022] Open
Abstract
Physio-logging has the potential to explore the processes that underlie the dive behavior and ecology of marine mammals and seabirds, as well as evaluate their adaptability to environmental change and other stressors. Regulation of heart rate lies at the core of the physiological processes that determine dive capacity and performance. The bio-logging of heart rate in unrestrained animals diving at sea was infeasible, even unimaginable in the mid-1970s. To provide a historical perspective, I review my 40-year experience in the development of heart rate physio-loggers and the evolution of a digital electrocardiogram (ECG) recorder that is still in use today. I highlight documentation of the ECG and the interpretation of heart rate profiles in the largest of avian and mammalian divers, the emperor penguin and blue whale.
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Affiliation(s)
- Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States
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9
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Williams CL, Ponganis PJ. Diving physiology of marine mammals and birds: the development of biologging techniques. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200211. [PMID: 34121464 PMCID: PMC8200650 DOI: 10.1098/rstb.2020.0211] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2021] [Indexed: 11/12/2022] Open
Abstract
In the 1940s, Scholander and Irving revealed fundamental physiological responses to forced diving of marine mammals and birds, setting the stage for the study of diving physiology. Since then, diving physiology research has moved from the laboratory to the field. Modern biologging, with the development of microprocessor technology, recorder memory capacity and battery life, has advanced and expanded investigations of the diving physiology of marine mammals and birds. This review describes a brief history of the start of field diving physiology investigations, including the invention of the time depth recorder, and then tracks the use of biologging studies in four key diving physiology topics: heart rate, blood flow, body temperature and oxygen store management. Investigations of diving heart rates in cetaceans and O2 store management in diving emperor penguins are highlighted to emphasize the value of diving physiology biologging research. The review concludes with current challenges, remaining diving physiology questions and what technologies are needed to advance the field. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.
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Affiliation(s)
- Cassondra L. Williams
- National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, CA 92106, USA
| | - Paul J. Ponganis
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
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10
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Williams CL, Hindle AG. Field Physiology: Studying Organismal Function in the Natural Environment. Compr Physiol 2021; 11:1979-2015. [PMID: 34190338 DOI: 10.1002/cphy.c200005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Continuous physiological measurements collected in field settings are essential to understand baseline, free-ranging physiology, physiological range and variability, and the physiological responses of organisms to disturbances. This article presents a current summary of the available technologies to continuously measure the direct physiological parameters in the field at high-resolution/instantaneous timescales from freely behaving animals. There is a particular focus on advantages versus disadvantages of available methods as well as emerging technologies "on the horizon" that may have been validated in captive or laboratory-based scenarios but have yet to be applied in the wild. Systems to record physiological variables from free-ranging animals are reviewed, including radio (VHF/UFH) telemetry, acoustic telemetry, and dataloggers. Physiological parameters that have been continuously measured in the field are addressed in seven sections including heart rate and electrocardiography (ECG); electromyography (EMG); electroencephalography (EEG); body temperature; respiratory, blood, and muscle oxygen; gastric pH and motility; and blood pressure and flow. The primary focal sections are heart rate and temperature as these can be, and have been, extensively studied in free-ranging organisms. Predicted aspects of future innovation in physiological monitoring are also discussed. The article concludes with an overview of best practices and points to consider regarding experimental designs, cautions, and effects on animals. © 2021 American Physiological Society. Compr Physiol 11:1979-2015, 2021.
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Affiliation(s)
- Cassondra L Williams
- National Marine Mammal Foundation, San Diego, California, USA.,Department of Ecology and Evolutionary Biology, School of Biological Science, University of California Irvine, Irvine, California, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
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11
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Williams CL, Czapanskiy MF, John JS, St Leger J, Scadeng M, Ponganis PJ. Cervical air sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store. J Exp Biol 2021; 224:jeb230219. [PMID: 33257430 DOI: 10.1242/jeb.230219] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 11/18/2020] [Indexed: 11/20/2022]
Abstract
Some marine birds and mammals can perform dives of extraordinary duration and depth. Such dive performance is dependent on many factors, including total body oxygen (O2) stores. For diving penguins, the respiratory system (air sacs and lungs) constitutes 30-50% of the total body O2 store. To better understand the role and mechanism of parabronchial ventilation and O2 utilization in penguins both on the surface and during the dive, we examined air sac partial pressures of O2 (PO2 ) in emperor penguins (Aptenodytes forsteri) equipped with backpack PO2 recorders. Cervical air sac PO2 values at rest were lower than in other birds, while the cervical air sac to posterior thoracic air sac PO2 difference was larger. Pre-dive cervical air sac PO2 values were often greater than those at rest, but had a wide range and were not significantly different from those at rest. The maximum respiratory O2 store and total body O2 stores calculated with representative anterior and posterior air sac PO2 data did not differ from prior estimates. The mean calculated anterior air sac O2 depletion rate for dives up to 11 min was approximately one-tenth that of the posterior air sacs. Low cervical air sac PO2 values at rest may be secondary to a low ratio of parabronchial ventilation to parabronchial blood O2 extraction. During dives, overlap of simultaneously recorded cervical and posterior thoracic air sac PO2 profiles supported the concept of maintenance of parabronchial ventilation during a dive by air movement through the lungs.
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Affiliation(s)
- Cassondra L Williams
- National Marine Mammal Foundation, 2240 Shelter Island Dr. #200, San Diego, CA 92106, USA
| | - Max F Czapanskiy
- Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA
| | - Jason S John
- Center for Ocean Health, Long Marine Laboratory, University of California, Santa Cruz, 115 McAlister Way, Santa Cruz, CA 95060, USA
| | - Judy St Leger
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
| | - Miriam Scadeng
- Department of Anatomy and Medical Imaging, Faculty of Health and Medical Sciences, University of Auckland, Auckland 1142, New Zealand
- Center for Functional Magnetic Resonance Imaging, University of California, San Diego, La Jolla, CA 92093, USA
| | - Paul J Ponganis
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
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12
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Kooyman GL, McDonald BI, Williams CL, Meir JU, Ponganis PJ. The aerobic dive limit: After 40 years, still rarely measured but commonly used. Comp Biochem Physiol A Mol Integr Physiol 2020; 252:110841. [PMID: 33186706 DOI: 10.1016/j.cbpa.2020.110841] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 11/15/2022]
Abstract
The aerobic dive limit (ADL) and the hypothesis that most dives are aerobic in nature have become fundamental to the understanding of diving physiology and to the interpretation of diving behavior and foraging ecology of marine mammals and seabirds. An ADL, the dive duration associated with the onset of post-dive blood lactate accumulation, has only been documented with blood lactate analyses in five species. Applications to other species have involved behavioral estimates or use of an oxygen store / metabolic rate formula. Both approaches have limitations, but have proved useful to the evaluation of the dive behavior and ecology of many species.
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Affiliation(s)
- Gerald L Kooyman
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Birgitte I McDonald
- Moss Landing Marine Laboratories, California State University, 8272 Moss Landing Road, Moss Landing, CA 95039, USA
| | - Cassondra L Williams
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, CA 92106, USA
| | | | - Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA.
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13
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Fahlman A, Sato K, Miller P. Improving estimates of diving lung volume in air-breathing marine vertebrates. ACTA ACUST UNITED AC 2020; 223:223/12/jeb216846. [PMID: 32587107 DOI: 10.1242/jeb.216846] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The air volume in the respiratory system of marine tetrapods provides a store of O2 to fuel aerobic metabolism during dives; however, it can also be a liability, as the associated N2 can increase the risk of decompression sickness. In order to more fully understand the physiological limitations of different air-breathing marine vertebrates, it is therefore important to be able to accurately estimate the air volume in the respiratory system during diving. One method that has been used to do so is to calculate the air volume from glide phases - periods of movement during which no thrust is produced by the animal - which many species conduct during ascent periods, when gases are expanding owing to decreasing hydrostatic pressure. This method assumes that there is conservation of mass in the respiratory system, with volume changes only driven by pressure. In this Commentary, we use previously published data to argue that both the respiratory quotient and differences in tissue and blood gas solubility potentially alter the mass balance in the respiratory system throughout a dive. Therefore, near the end of a dive, the measured volume of gas at a given pressure may be 12-50% less than from the start of the dive; the actual difference will depend on the length of the dive, the cardiac output, the pulmonary shunt and the metabolic rate. Novel methods and improved understanding of diving physiology will be required to verify the size of the effects described here and to more accurately estimate the volume of gas inhaled at the start of a dive.
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Affiliation(s)
- Andreas Fahlman
- Global Diving Research Inc., Ottawa, ON, Canada, K2J 5E8 .,Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
| | - Katsufumi Sato
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Patrick Miller
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
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15
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McDonald BI, Tift MS, Hückstädt LA, Jeffko M, Ponganis PJ. Stroke effort and relative lung volume influence heart rate in diving sea lions. J Exp Biol 2020; 223:jeb214163. [PMID: 32098880 DOI: 10.1242/jeb.214163] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 02/10/2020] [Indexed: 11/20/2022]
Abstract
The dive response, bradycardia (decreased heart rate) and peripheral vasoconstriction, is the key mechanism allowing breath-hold divers to perform long-duration dives while actively swimming and hunting prey. This response is variable and modulated by factors such as dive duration, depth, exercise and cognitive control. This study assessed the potential role of exercise and relative lung volume in the regulation of heart rate (fH) during dives of adult female California sea lions instrumented with electrocardiogram (ECG), depth and tri-axial acceleration data loggers. A positive relationship between activity (minimum specific acceleration) and fH throughout dives suggested increased muscle perfusion associated with exercise. However, apart from late ascent, fH during dives was still less than or equal to resting fH (on land). In addition, the activity-fH relationship was weaker in long, deep dives consistent with prioritization of blood oxygen conservation over blood oxygen delivery to muscle in those dives. Pulmonary stretch receptor reflexes may also contribute to fH regulation as fH profiles generally paralleled changes in relative lung volume, especially in shallower dives and during early descent and late ascent of deeper dives. Overall, these findings support the concept that both exercise and pulmonary stretch receptor reflexes may influence the dive response in sea lions.
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Affiliation(s)
- Birgitte I McDonald
- Moss Landing Marine Laboratories, San Jose State University, 8272 Moss Landing Rd, Moss Landing, CA 95039, USA
| | - Michael S Tift
- Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Rd, Wilmington, NC 28403, USA
| | - Luis A Hückstädt
- Institute of Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA 95060, USA
| | - Michael Jeffko
- United States Coast Guard Academy, 27 Mohegan Way, New London, CT 06320, USA
| | - Paul J Ponganis
- Scripps Institution of Oceanography - University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
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16
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Lapsansky AB, Tobalske BW. Upstroke-based acceleration and head stabilization are the norm for the wing-propelled swimming of alcid seabirds. ACTA ACUST UNITED AC 2019; 222:jeb.201285. [PMID: 31160426 DOI: 10.1242/jeb.201285] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/28/2019] [Indexed: 11/20/2022]
Abstract
Alcids, a family of seabirds including murres, guillemots and puffins, exhibit the greatest mass-specific dive depths and durations of any birds or mammals. These impressive diving capabilities have motivated numerous studies on the biomechanics of alcid swimming and diving, with one objective being to compare stroke-acceleration patterns of swimming alcids with those of penguins, where upstroke and downstroke are used for horizontal acceleration. Studies of free-ranging, descending alcids have found that alcids accelerate in the direction of travel during both their upstroke and downstroke, but only at depths <20 m, whereas studies of alcids swimming horizontally report upstroke-based acceleration to be rare (≤16% of upstrokes). We hypothesized that swimming trajectory, via its interaction with buoyancy, determines the magnitude of acceleration produced during the upstroke. Thus, we studied the stroke-acceleration relationships of five species of alcid swimming freely at the Alaska SeaLife Center using videography and kinematic analysis. Contrary to our prediction, we found that upstroke-based acceleration is very common (87% of upstrokes) during both descending and horizontal swimming. We reveal that head-damping - wherein an animal extends and retracts its head to offset periodic accelerations - is common in swimming alcids, underscoring the importance of head stabilization during avian locomotion.
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Affiliation(s)
- Anthony B Lapsansky
- Field Research Station at Fort Missoula, Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
| | - Bret W Tobalske
- Field Research Station at Fort Missoula, Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
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17
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Tift MS, Ponganis PJ. Time Domains of Hypoxia Adaptation-Elephant Seals Stand Out Among Divers. Front Physiol 2019; 10:677. [PMID: 31214049 PMCID: PMC6558045 DOI: 10.3389/fphys.2019.00677] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 05/13/2019] [Indexed: 11/17/2022] Open
Affiliation(s)
- Michael S. Tift
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, United States
| | - Paul J. Ponganis
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, United States
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18
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Mattern T, McPherson MD, Ellenberg U, van Heezik Y, Seddon PJ. High definition video loggers provide new insights into behaviour, physiology, and the oceanic habitat of a marine predator, the yellow-eyed penguin. PeerJ 2018; 6:e5459. [PMID: 30258706 PMCID: PMC6151119 DOI: 10.7717/peerj.5459] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/24/2018] [Indexed: 11/24/2022] Open
Abstract
Camera loggers are increasingly used to examine behavioural aspects of free-ranging animals. However, often video loggers are deployed with a focus on specific behavioural traits utilizing small cameras with a limited field of view, poor light performance and video quality. Yet rapid developments in consumer electronics provide new devices with much improved visual data allowing a wider scope for studies employing this novel methodology. We developed a camera logger that records full HD video through a wide-angle lens, providing high resolution footage with a greater field of view than other camera loggers. The main goal was to assess the suitability of this type of camera for the analysis of various aspects of the foraging ecology of a marine predator, the yellow-eyed penguin in New Zealand. Frame-by-frame analysis allowed accurate timing of prey pursuits and time spent over certain seafloor types. The recorded video footage showed that prey species were associated with certain seafloor types, revealed different predator evasion strategies by benthic fishes, and highlighted varying energetic consequences for penguins pursuing certain types of prey. Other aspects that could be analysed were the timing of breathing intervals between dives and observe exhalation events during prey pursuits, a previously undescribed behaviour. Screen overlays facilitated analysis of flipper angles and beat frequencies throughout various stages of the dive cycle. Flipper movement analysis confirmed decreasing effort during descent phases as the bird gained depth, and that ascent was principally passive. Breathing episodes between dives were short (<1 s) while the majority of the time was devoted to subsurface scanning with a submerged head. Video data recorded on free-ranging animals not only provide a wealth of information recorded from a single deployment but also necessitate new approaches with regards to analysis of visual data. Here, we demonstrate the diversity of information that can be gleaned from video logger data, if devices with high video resolution and wide field of view are utilized.
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Affiliation(s)
- Thomas Mattern
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand.,Global Penguin Society, Puerto Madryn, Chubut, Argentina
| | | | - Ursula Ellenberg
- Global Penguin Society, Puerto Madryn, Chubut, Argentina.,Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Victoria, Australia
| | | | - Philipp J Seddon
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand
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19
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Mattern T, McPherson MD, Ellenberg U, van Heezik Y, Seddon PJ. High definition video loggers provide new insights into behaviour, physiology, and the oceanic habitat of a marine predator, the yellow-eyed penguin. PeerJ 2018; 6:e5459. [PMID: 30258706 DOI: 10.7287/peerj.preprints.2765v2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/24/2018] [Indexed: 05/27/2023] Open
Abstract
Camera loggers are increasingly used to examine behavioural aspects of free-ranging animals. However, often video loggers are deployed with a focus on specific behavioural traits utilizing small cameras with a limited field of view, poor light performance and video quality. Yet rapid developments in consumer electronics provide new devices with much improved visual data allowing a wider scope for studies employing this novel methodology. We developed a camera logger that records full HD video through a wide-angle lens, providing high resolution footage with a greater field of view than other camera loggers. The main goal was to assess the suitability of this type of camera for the analysis of various aspects of the foraging ecology of a marine predator, the yellow-eyed penguin in New Zealand. Frame-by-frame analysis allowed accurate timing of prey pursuits and time spent over certain seafloor types. The recorded video footage showed that prey species were associated with certain seafloor types, revealed different predator evasion strategies by benthic fishes, and highlighted varying energetic consequences for penguins pursuing certain types of prey. Other aspects that could be analysed were the timing of breathing intervals between dives and observe exhalation events during prey pursuits, a previously undescribed behaviour. Screen overlays facilitated analysis of flipper angles and beat frequencies throughout various stages of the dive cycle. Flipper movement analysis confirmed decreasing effort during descent phases as the bird gained depth, and that ascent was principally passive. Breathing episodes between dives were short (<1 s) while the majority of the time was devoted to subsurface scanning with a submerged head. Video data recorded on free-ranging animals not only provide a wealth of information recorded from a single deployment but also necessitate new approaches with regards to analysis of visual data. Here, we demonstrate the diversity of information that can be gleaned from video logger data, if devices with high video resolution and wide field of view are utilized.
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Affiliation(s)
- Thomas Mattern
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand
- Global Penguin Society, Puerto Madryn, Chubut, Argentina
| | | | - Ursula Ellenberg
- Global Penguin Society, Puerto Madryn, Chubut, Argentina
- Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Victoria, Australia
| | | | - Philipp J Seddon
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand
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20
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Arranz P, Benoit-Bird KJ, Southall BL, Calambokidis J, Friedlaender AS, Tyack PL. Risso's dolphins plan foraging dives. J Exp Biol 2018; 221:221/4/jeb165209. [DOI: 10.1242/jeb.165209] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 12/18/2017] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Humans remember the past and use that information to plan future actions. Lab experiments that test memory for the location of food show that animals have a similar capability to act in anticipation of future needs, but less work has been done on animals foraging in the wild. We hypothesized that planning abilities are critical and common in breath-hold divers who adjust each dive to forage on prey varying in quality, location and predictability within constraints of limited oxygen availability. We equipped Risso's dolphins with sound-and-motion recording tags to reveal where they focus their attention through their externally observable echolocation and how they fine tune search strategies in response to expected and observed prey distribution. The information from the dolphins was integrated with synoptic prey data obtained from echosounders on an underwater vehicle. At the start of the dives, whales adjusted their echolocation inspection ranges in ways that suggest planning to forage at a particular depth. Once entering a productive prey layer, dolphins reduced their search range comparable to the scale of patches within the layer, suggesting that they were using echolocation to select prey within the patch. On ascent, their search range increased, indicating that they decided to stop foraging within that layer and started searching for prey in shallower layers. Information about prey, learned throughout the dive, was used to plan foraging in the next dive. Our results demonstrate that planning for future dives is modulated by spatial memory derived from multi-modal prey sampling (echoic, visual and capture) during earlier dives.
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Affiliation(s)
- Patricia Arranz
- Sea Mammal Research Unit, School of Biology, University of St Andrews, East Sands, St Andrews KY16 8LB, UK
- Department of Animal Biology, University of La Laguna, Avda. Astrofisico Fco Sanchez s/n, La Laguna 36200, Tenerife, Spain
| | - Kelly J. Benoit-Bird
- Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, USA
| | - Brandon L. Southall
- Southall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USA
- Long Marine Laboratory, Institute of Marine Sciences, University of California Santa Cruz, 1156 High St, Santa Cruz, CA 95064, USA
| | - John Calambokidis
- Cascadia Research Collective, 218 1/2 4th Ave W, Olympia, WA 98501, USA
| | - Ari S. Friedlaender
- Southall Environmental Associates, 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USA
- Department of Fisheries and Wildlife, Marine Mammal Institute, 2030 Marine Science Drive, Newport, OR 97365, USA
| | - Peter L. Tyack
- Sea Mammal Research Unit, School of Biology, University of St Andrews, East Sands, St Andrews KY16 8LB, UK
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21
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Tift MS, Hückstädt LA, Ponganis PJ. Anterior vena caval oxygen profiles in a deep-diving California sea lion: arteriovenous shunts, a central venous oxygen store and oxygenation during lung collapse. ACTA ACUST UNITED AC 2018; 221:jeb.163428. [PMID: 29084854 DOI: 10.1242/jeb.163428] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 10/26/2017] [Indexed: 11/20/2022]
Abstract
Deep-diving California sea lions (Zalophus californianus) can maintain arterial hemoglobin saturation (SO2 ) above 90% despite lung collapse (lack of gas exchange) and extremely low posterior vena caval SO2 in the middle of the dive. We investigated anterior vena caval PO2 and SO2 during dives of an adult female sea lion to investigate two hypotheses: (1) posterior vena caval SO2 is not representative of the entire venous oxygen store and (2) a well-oxygenated (arterialized) central venous oxygen reservoir might account for maintenance of arterial SO2 during lung collapse. During deep dives, initial anterior vena caval SO2 was elevated at 83.6±8.4% (n=102), presumably owing to arteriovenous shunting. It remained high until the bottom phase of the dive and then decreased during ascent, whereas previously determined posterior vena caval SO2 declined during descent and then often increased during ascent. These divergent patterns confirmed that posterior vena caval SO2 was not representative of the entire venous oxygen store. Prior to and early during descent of deep dives, the high SO2 values of both the anterior and posterior venae cavae may enhance arterialization of a central venous oxygen store. However, anterior vena caval SO2 values at depths beyond lung collapse reached levels as low as 40%, making it unlikely that even a completely arterialized central venous oxygen store could account for maintenance of high arterial SO2 These findings suggest that maintenance of high arterial SO2 during deep dives is due to persistence of some gas exchange at depths beyond presumed lung collapse.
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Affiliation(s)
- Michael S Tift
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biotechnology and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
| | - Luis A Hückstädt
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Long Marine Laboratory, 130 McAllister Way, Santa Cruz, CA 95060, USA
| | - Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biotechnology and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
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22
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Ladds MA, Rosen DAS, Slip DJ, Harcourt RG. Proxies of energy expenditure for marine mammals: an experimental test of "the time trap". Sci Rep 2017; 7:11815. [PMID: 28924150 PMCID: PMC5603582 DOI: 10.1038/s41598-017-11576-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/23/2017] [Indexed: 11/25/2022] Open
Abstract
Direct measures of energy expenditure are difficult to obtain in marine mammals, and accelerometry may be a useful proxy. Recently its utility has been questioned as some analyses derived their measure of activity level by calculating the sum of accelerometry-based values and then comparing this summation to summed (total) energy expenditure (the so-called “time trap”). To test this hypothesis, we measured oxygen consumption of captive fur seals and sea lions wearing accelerometers during submerged swimming and calculated total and rate of energy expenditure. We compared these values with two potential proxies of energy expenditure derived from accelerometry data: flipper strokes and dynamic body acceleration (DBA). Total number of strokes, total DBA, and submergence time all predicted total oxygen consumption \documentclass[12pt]{minimal}
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\begin{document}$$({\boldsymbol{sV}}{{\boldsymbol{O}}}_{{\boldsymbol{2}}}$$\end{document}(sVO2 ml kg−1). However, both total DBA and total number of strokes were correlated with submergence time. Neither stroke rate nor mean DBA could predict the rate of oxygen consumption (\documentclass[12pt]{minimal}
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\begin{document}$$s\mathop{{\boldsymbol{V}}}\limits^{{\boldsymbol{.}}}{{\boldsymbol{O}}}_{{\boldsymbol{2}}}$$\end{document}sV.O2 ml min−1 kg−1). The relationship of total DBA and total strokes with total oxygen consumption is apparently a result of introducing a constant (time) into both sides of the relationship. This experimental evidence supports the conclusion that proxies derived from accelerometers cannot estimate the energy expenditure of marine mammals.
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Affiliation(s)
- Monique A Ladds
- School of Mathematics and Statistics, Victoria University of Wellington, Wellington, 6012, New Zealand. .,Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, 2113, NSW, Australia.
| | - David A S Rosen
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - David J Slip
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, 2113, NSW, Australia.,Taronga Conservation Society Australia, Bradley's Head Road, Mosman, 2088, NSW, Australia
| | - Robert G Harcourt
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, 2113, NSW, Australia
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23
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Lewden A, Enstipp MR, Picard B, van Walsum T, Handrich Y. High peripheral temperatures in king penguins while resting at sea: thermoregulation versus fat deposition. ACTA ACUST UNITED AC 2017. [PMID: 28623225 DOI: 10.1242/jeb.158980] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Marine endotherms living in cold water face an energetically challenging situation. Unless properly insulated, these animals will lose heat rapidly. The field metabolic rate of king penguins at sea is about twice that on land. However, when at sea, their metabolic rate is higher during extended resting periods at the surface than during foraging, when birds descend to great depth in pursuit of their prey. This is most likely explained by differences in thermal status. During foraging, peripheral vasoconstriction leads to a hypothermic shell, which is rewarmed during extended resting bouts at the surface. Maintaining peripheral perfusion during rest in cold water, however, will greatly increase heat loss and, therefore, thermoregulatory costs. Two hypotheses have been proposed to explain the maintenance of a normothermic shell during surface rest: (1) to help the unloading of N2 accumulated during diving; and (2) to allow the storage of fat in subcutaneous tissue, following the digestion of food. We tested the latter hypothesis by maintaining king penguins within a shallow seawater tank, while we recorded tissue temperature at four distinct sites. When king penguins were released into the tank during the day, their body temperature immediately declined. However, during the night, periodic rewarming of abdominal and peripheral tissues occurred, mimicking temperature patterns observed in the wild. Body temperatures, particularly in the flank, also depended on body condition and were higher in 'lean' birds (after 10 days of fasting) than in 'fat' birds. While not explicitly tested, our observation that nocturnal rewarming persists in the absence of diving activity during the day does not support the N2 unloading hypothesis. Rather, differences in temperature changes throughout the day and night, and the effect of body condition/mass supports the hypothesis that tissue perfusion during rest is required for nutritional needs.
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Affiliation(s)
- Agnès Lewden
- Université de Strasbourg, CNRS, Département Ecologie, Physiologie et Ethologie, IPHC UMR 7178, F-67000 Strasbourg, France
| | - Manfred R Enstipp
- Université de Strasbourg, CNRS, Département Ecologie, Physiologie et Ethologie, IPHC UMR 7178, F-67000 Strasbourg, France.,Centre d'Etudes Biologiques de Chizé, CNRS, UMR 7372, 79360 Villiers en Bois, France
| | - Baptiste Picard
- Centre d'Etudes Biologiques de Chizé, CNRS, UMR 7372, 79360 Villiers en Bois, France
| | - Tessa van Walsum
- University of Roehampton, Department of Life Sciences, London SW15 4JD, UK
| | - Yves Handrich
- Université de Strasbourg, CNRS, Département Ecologie, Physiologie et Ethologie, IPHC UMR 7178, F-67000 Strasbourg, France
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24
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Tift MS, Hückstädt LA, McDonald BI, Thorson PH, Ponganis PJ. Flipper stroke rate and venous oxygen levels in free-ranging California sea lions. ACTA ACUST UNITED AC 2017; 220:1533-1540. [PMID: 28167807 DOI: 10.1242/jeb.152314] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 02/01/2017] [Indexed: 11/20/2022]
Abstract
The depletion rate of the blood oxygen store, development of hypoxemia and dive capacity are dependent on the distribution and rate of blood oxygen delivery to tissues while diving. Although blood oxygen extraction by working muscle would increase the blood oxygen depletion rate in a swimming animal, there is little information on the relationship between muscle workload and blood oxygen depletion during dives. Therefore, we examined flipper stroke rate, a proxy of muscle workload, and posterior vena cava oxygen profiles in four adult female California sea lions (Zalophus californianus) during foraging trips at sea. Flipper stroke rate analysis revealed that sea lions minimized muscle metabolism with a stroke-glide strategy when diving, and exhibited prolonged glides during the descent of deeper dives (>100 m). During the descent phase of these deep dives, 55±21% of descent was spent gliding, with the longest glides lasting over 160 s and covering a vertical distance of 340 m. Animals also consistently glided to the surface from 15 to 25 m depth during these deeper dives. Venous hemoglobin saturation (SO2 ) profiles were highly variable throughout dives, with values occasionally increasing during shallow dives. The relationship between SO2 and flipper stroke rate was weak during deeper dives, while this relationship was stronger during shallow dives. We conclude that (1) the depletion of oxygen in the posterior vena cava in deep-diving sea lions is not dependent on stroke effort, and (2) stroke-glide patterns during dives contribute to a reduction of muscle metabolic rate.
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Affiliation(s)
- Michael S Tift
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
| | - Luis A Hückstädt
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Long Marine Lab, 100 Shaffer Road, Santa Cruz, CA 95060, USA
| | - Birgitte I McDonald
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA
| | - Philip H Thorson
- Institute of Marine Sciences, University of California Santa Cruz, Long Marine Laboratory, 100 Shaffer Road, CA 95060, USA
| | - Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
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25
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Miller P, Narazaki T, Isojunno S, Aoki K, Smout S, Sato K. Body density and diving gas volume of the northern bottlenose whale (Hyperoodon ampullatus). J Exp Biol 2016; 219:2458-68. [PMID: 27296044 PMCID: PMC5004977 DOI: 10.1242/jeb.137349] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 05/31/2016] [Indexed: 11/27/2022]
Abstract
Diving lung volume and tissue density, reflecting lipid store volume, are important physiological parameters that have only been estimated for a few breath-hold diving species. We fitted 12 northern bottlenose whales with data loggers that recorded depth, 3-axis acceleration and speed either with a fly-wheel or from change of depth corrected by pitch angle. We fitted measured values of the change in speed during 5 s descent and ascent glides to a hydrodynamic model of drag and buoyancy forces using a Bayesian estimation framework. The resulting estimate of diving gas volume was 27.4±4.2 (95% credible interval, CI) ml kg(-1), closely matching the measured lung capacity of the species. Dive-by-dive variation in gas volume did not correlate with dive depth or duration. Estimated body densities of individuals ranged from 1028.4 to 1033.9 kg m(-3) at the sea surface, indicating overall negative tissue buoyancy of this species in seawater. Body density estimates were highly precise with ±95% CI ranging from 0.1 to 0.4 kg m(-3), which would equate to a precision of <0.5% of lipid content based upon extrapolation from the elephant seal. Six whales tagged near Jan Mayen (Norway, 71°N) had lower body density and were closer to neutral buoyancy than six whales tagged in the Gully (Nova Scotia, Canada, 44°N), a difference that was consistent with the amount of gliding observed during ascent versus descent phases in these animals. Implementation of this approach using longer-duration tags could be used to track longitudinal changes in body density and lipid store body condition of free-ranging cetaceans.
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Affiliation(s)
- Patrick Miller
- Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife KY16 9QQ, UK Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Tomoko Narazaki
- Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife KY16 9QQ, UK Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Saana Isojunno
- Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife KY16 9QQ, UK
| | - Kagari Aoki
- Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife KY16 9QQ, UK Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Sophie Smout
- Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife KY16 9QQ, UK
| | - Katsufumi Sato
- Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
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26
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Diving physiology of seabirds and marine mammals: Relevance, challenges and some solutions for field studies. Comp Biochem Physiol A Mol Integr Physiol 2016; 202:38-52. [PMID: 27421239 DOI: 10.1016/j.cbpa.2016.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 07/06/2016] [Accepted: 07/06/2016] [Indexed: 11/20/2022]
Abstract
To fully understand how diving seabirds and marine mammals balance the potentially conflicting demands of holding their breath while living their lives underwater (and maintaining physiological homeostasis during exercise, feeding, growth, and reproduction), physiological studies must be conducted with animals in their natural environments. The purpose of this article is to review the importance of making physiological measurements on diving animals in field settings, while acknowledging the challenges and highlighting some solutions. The most extreme divers are great candidates for study, especially in a comparative and mechanistic context. However, physiological data are also required of a wide range of species for problems relating to other disciplines, in particular ecology and conservation biology. Physiological data help with understanding and predicting the outcomes of environmental change, and the direct impacts of anthropogenic activities. Methodological approaches that have facilitated the development of field-based diving physiology include the isolated diving hole protocol and the translocation paradigm, and while there are many techniques for remote observation, animal-borne biotelemetry, or "biologging", has been critical. We discuss issues related to the attachment of instruments, the retrieval of data and sensing of physiological variables, while also considering negative impacts of tagging. This is illustrated with examples from a variety of species, and an in-depth look at one of the best studied and most extreme divers, the emperor penguin (Aptenodytes forsteri). With a variety of approaches and high demand for data on the physiology of diving seabirds and marine mammals, the future of field studies is bright.
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Hückstädt LA, Tift MS, Riet-Sapriza F, Franco-Trecu V, Baylis AMM, Orben RA, Arnould JPY, Sepulveda M, Santos-Carvallo M, Burns JM, Costa DP. Regional variability in diving physiology and behavior in a widely distributed air-breathing marine predator, the South American sea lion (Otaria byronia). ACTA ACUST UNITED AC 2016; 219:2320-30. [PMID: 27247316 DOI: 10.1242/jeb.138677] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/17/2016] [Indexed: 11/20/2022]
Abstract
Our understanding of how air-breathing marine predators cope with environmental variability is limited by our inadequate knowledge of their ecological and physiological parameters. Because of their wide distribution along both coasts of the sub-continent, South American sea lions (Otaria byronia) provide a valuable opportunity to study the behavioral and physiological plasticity of a marine predator in different environments. We measured the oxygen stores and diving behavior of South American sea lions throughout most of its range, allowing us to demonstrate that diving ability and behavior vary across its range. We found no significant differences in mass-specific blood volumes of sea lions among field sites and a negative relationship between mass-specific oxygen storage and size, which suggests that exposure to different habitats and geographical locations better explains oxygen storage capacities and diving capability in South American sea lions than body size alone. The largest animals in our study (individuals from Uruguay) were the shallowest and shortest duration divers, and had the lowest mass-specific total body oxygen stores, while the deepest and longest duration divers (individuals from southern Chile) had significantly larger mass-specific oxygen stores, despite being much smaller animals. Our study suggests that the physiology of air-breathing diving predators is not fixed, but that it can be adjusted, to a certain extent, depending on the ecological setting and or habitat. These adjustments can be thought of as a 'training effect': as the animal continues to push its physiological capacity through greater hypoxic exposure, its breath-holding capacity increases.
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Affiliation(s)
- Luis A Hückstädt
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Long Marine Laboratory, 100 Shaffer Road, Santa Cruz, CA 95060, USA
| | - Michael S Tift
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
| | - Federico Riet-Sapriza
- Laboratorio de Ecologia Molecular de Vertebrados Acuaticos (LEMVA), Departamento de Ciencias Biologicas, Facultad de Ciencias, Universidad de Los Andes, Carrera 1E, #18A-10, Bogota, Colombia
| | - Valentina Franco-Trecu
- Departamento de Ecología y Evolución Facultad de Ciencias, Universidad de la República, Iguá 4225 Esq. Mataojo C.P, 11400 Montevideo, Uruguay
| | - Alastair M M Baylis
- South Atlantic Environmental Research Institute, Stanley FIQQ1ZZ, Falkland Islands School of Life and Environmental Sciences, Deakin University, Warrnambool Campus, Geelong, Australia
| | - Rachael A Orben
- Hatfield Marine Science Center, Oregon State University, 2030 SE Marine Science Drive, Newport, OR 97365, USA
| | - John P Y Arnould
- School of Life and Environmental Sciences, Deakin University, Burwood Campus, Geelong, Australia
| | - Maritza Sepulveda
- Centro de Investigación y Gestión en Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
| | - Macarena Santos-Carvallo
- Centro de Investigación y Gestión en Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
| | - Jennifer M Burns
- Department of Biological Sciences, University of Alaska Anchorage. 3211 Providence Drive Anchorage, AK 99508, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Long Marine Laboratory, 100 Shaffer Road, Santa Cruz, CA 95060, USA
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Martín López LM, Aguilar de Soto N, Miller P, Johnson M. Tracking the kinematics of caudal-oscillatory swimming: a comparison of two on-animal sensing methods. ACTA ACUST UNITED AC 2016; 219:2103-9. [PMID: 27207638 DOI: 10.1242/jeb.136242] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 05/11/2016] [Indexed: 11/20/2022]
Abstract
Studies of locomotion kinematics require high-resolution information about body movements and the specific acceleration (SA) that these generate. On-animal accelerometers measure both orientation and SA but an additional orientation sensor is needed to accurately separate these. Although gyroscopes can perform this function, their power consumption, drift and complex data processing make them unattractive for biologging. Lower power magnetometers can also be used with some limitations. Here, we present an integrated and simplified method for estimating body rotations and SA applicable to both gyroscopes and magnetometers, enabling a direct comparison of these two sensors. We use a tag with both sensors to demonstrate how caudal-oscillation rate and SA are adjusted by a diving whale in response to rapidly changing buoyancy forces as the lungs compress while descending. The two sensors gave similar estimates of the dynamic forces, demonstrating that magnetometers may offer a simpler low-power alternative for miniature tags in some applications.
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Affiliation(s)
- Lucía Martina Martín López
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK Asociación Ipar Perspective, C/Karabiondo 17, 48600 Sopela, Bizkaia, Spain
| | - Natacha Aguilar de Soto
- CREEM (Centre for Research in Ecological and Environmental Modelling), University of St Andrews, Fife KY16 9LZ, UK BIOECOMAC (Biodiversidad, Ecología Marina y Conservación), Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain
| | - Patrick Miller
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - Mark Johnson
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK Zoophysiology, Department of Bioscience, Aarhus University, Building 1131, C. F. Moellers Alle 3, Aarhus C DK-8000, Denmark
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Trassinelli M. Energy cost and optimisation in breath-hold diving. J Theor Biol 2016; 396:42-52. [PMID: 26896829 DOI: 10.1016/j.jtbi.2016.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 02/04/2016] [Accepted: 02/08/2016] [Indexed: 10/22/2022]
Abstract
We present a new model for calculating locomotion costs in breath-hold divers. Starting from basic mechanics principles, we calculate the work that the diver must provide through propulsion to counterbalance the action of drag, the buoyant force and weight during immersion. Compared to those in previous studies, the model presented here accurately analyses breath-hold divers which alternate active swimming with prolonged glides during the dive (as is the case in mammals). The energy cost of the dive is strongly dependent on these prolonged gliding phases. Here we investigate the length and impacts on energy cost of these glides with respect to the diver characteristics, and compare them with those observed in different breath-hold diving species. Taking into account the basal metabolic rate and chemical energy to propulsion transformation efficiency, we calculate optimal swim velocity and the corresponding total energy cost (including metabolic rate) and compare them with observations. Energy cost is minimised when the diver passes through neutral buoyancy conditions during the dive. This generally implies the presence of prolonged gliding phases in both ascent and descent, where the buoyancy (varying with depth) is best used against the drag, reducing energy cost. This is in agreement with past results (Miller et al., 2012; Sato et al., 2013) where, when the buoyant force is considered constant during the dive, the energy cost was minimised for neutral buoyancy. In particular, our model confirms the good physical adaption of dolphins for diving, compared to other breath-hold diving species which are mostly positively buoyant (penguins for example). The presence of prolonged glides implies a non-trivial dependency of optimal speed on maximal depth of the dive. This extends previous findings (Sato et al., 2010; Watanabe et al., 2011) which found no dependency of optimal speed on dive depth for particular conditions. The energy cost of the dive can be further diminished by reducing the volume of gas-filled body parts in divers close to neutral buoyancy. This provides a possible additional explanation for the observed exhalation of air before diving in phocid seals to minimise dive energy cost. Until now the only explanation for this phenomenon has been a reduction in the risk of decompression sickness.
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Affiliation(s)
- M Trassinelli
- Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris, France.
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Willener AST, Handrich Y, Halsey LG, Strike S. Effect of walking speed on the gait of king penguins: An accelerometric approach. J Theor Biol 2015; 387:166-73. [PMID: 26427338 DOI: 10.1016/j.jtbi.2015.09.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 08/20/2015] [Accepted: 09/15/2015] [Indexed: 10/23/2022]
Abstract
Little is known about non-human bipedal gaits. This is probably due to the fact that most large animals are quadrupedal and that non-human bipedal animals are mostly birds, whose primary form of locomotion is flight. Very little research has been conducted on penguin pedestrian locomotion with the focus instead on their associated high energy expenditure. In animals, tri-axial accelerometers are frequently used to estimate physiological energy cost, as well as to define the behaviour pattern of a species, or the kinematics of swimming. In this study, we showed how an accelerometer-based technique could be used to determine the biomechanical characteristics of pedestrian locomotion. Eight king penguins, which represent the only family of birds to have an upright bipedal gait, were trained to walk on a treadmill. The trunk tri-axial accelerations were recorded while the bird was walking at four different speeds (1.0, 1.2, 1.4 and 1.6km/h), enabling the amplitude of dynamic body acceleration along the three axes (amplitude of DBAx, DBAy and DBAz), stride frequency, waddling and leaning amplitude, as well as the leaning angle to be defined. The magnitude of the measured variables showed a significant increase with increasing speed, apart from the backwards angle of lean, which decreased with increasing speed. The variability of the measured variables also showed a significant increase with speed apart from the DBAz amplitude, the waddling amplitude, and the leaning angle, where no significant effect of the walking speed was found. This paper is the first approach to describe 3D biomechanics with an accelerometer on wild animals, demonstrating the potential of this technique.
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Affiliation(s)
- Astrid S T Willener
- Department of Life Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK; Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR7178, 67087 Strasbourg, France.
| | - Yves Handrich
- Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR7178, 67087 Strasbourg, France
| | - Lewis G Halsey
- Department of Life Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK
| | - Siobhán Strike
- Department of Life Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK
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Ponganis PJ, St Leger J, Scadeng M. Penguin lungs and air sacs: implications for baroprotection, oxygen stores and buoyancy. J Exp Biol 2015; 218:720-30. [DOI: 10.1242/jeb.113647] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
The anatomy and volume of the penguin respiratory system contribute significantly to pulmonary baroprotection, the body O2 store, buoyancy and hence the overall diving physiology of penguins. Therefore, three-dimensional reconstructions from computerized tomographic (CT) scans of live penguins were utilized to measure lung volumes, air sac volumes, tracheobronchial volumes and total body volumes at different inflation pressures in three species with different dive capacities [Adélie (Pygoscelis adeliae), king (Aptenodytes patagonicus) and emperor (A. forsteri) penguins]. Lung volumes scaled to body mass according to published avian allometrics. Air sac volumes at 30 cm H2O (2.94 kPa) inflation pressure, the assumed maximum volume possible prior to deep dives, were two to three times allometric air sac predictions and also two to three times previously determined end-of-dive total air volumes. Although it is unknown whether penguins inhale to such high volumes prior to dives, these values were supported by (a) body density/buoyancy calculations, (b) prior air volume measurements in free-diving ducks and (c) previous suggestions that penguins may exhale air prior to the final portions of deep dives. Based upon air capillary volumes, parabronchial volumes and tracheobronchial volumes estimated from the measured lung/airway volumes and the only available morphometry study of a penguin lung, the presumed maximum air sac volumes resulted in air sac volume to air capillary/parabronchial/tracheobronchial volume ratios that were not large enough to prevent barotrauma to the non-collapsing, rigid air capillaries during the deepest dives of all three species, and during many routine dives of king and emperor penguins. We conclude that volume reduction of airways and lung air spaces, via compression, constriction or blood engorgement, must occur to provide pulmonary baroprotection at depth. It is also possible that relative air capillary and parabronchial volumes are smaller in these deeper-diving species than in the spheniscid penguin of the morphometry study. If penguins do inhale to this maximum air sac volume prior to their deepest dives, the magnitude and distribution of the body O2 store would change considerably. In emperor penguins, total body O2 would increase by 75%, and the respiratory fraction would increase from 33% to 61%. We emphasize that the maximum pre-dive respiratory air volume is still unknown in penguins. However, even lesser increases in air sac volume prior to a dive would still significantly increase the O2 store. More refined evaluations of the respiratory O2 store and baroprotective mechanisms in penguins await further investigation of species-specific lung morphometry, start-of-dive air volumes and body buoyancy, and the possibility of air exhalation during dives.
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Affiliation(s)
- P. J. Ponganis
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, 9500 Gilman Drive 0204, La Jolla, CA 92093-0204, USA
| | - J. St Leger
- SeaWorld, 500 SeaWorld Drive, San Diego, CA 92109, USA
| | - M. Scadeng
- UC San Diego Center for Functional MRI, 9500 Gilman Drive 0677, La Jolla CA 92093-0677, USA
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32
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Kooyman G. Marine mammals and Emperor penguins: a few applications of the Krogh principle. Am J Physiol Regul Integr Comp Physiol 2014; 308:R96-104. [PMID: 25411360 DOI: 10.1152/ajpregu.00264.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The diving physiology of aquatic animals at sea began 50 years ago with studies of the Weddell seal. Even today with the advancements in marine recording and tracking technology, only a few species are suitable for investigation. The first experiments were in McMurdo Sound, Antarctica. In this paper are examples of what was learned in Antarctica and elsewhere. Some methods employed relied on willingness of Weddell seals and emperor penguins to dive under sea ice. Diving depth and duration were obtained with a time depth recorder. Some dives were longer than an hour and as deep as 600 m. From arterial blood samples, lactate and nitrogen concentrations were obtained. These results showed how Weddell seals manage their oxygen stores, that they become reliant on a positive contribution of anaerobic metabolism during a dive duration of more than 20 min, and that nitrogen blood gases remain so low that lung collapse must occur at about 25 to 50 m. This nitrogen level was similar to that determined in elephant seals during forcible submersion with compression to depths greater than 100 m. These results led to further questions about diving mammal's terminal airway structure in the lungs. Much of the strengthening of the airways is not for avoiding the "bends," by enhancing lung collapse at depth, but for reducing the resistance to high flow rates during expiration. The most exceptional examples are the small whales that maintain high expiratory flow rates throughout the entire vital capacity, which represents about 90% of their total lung capacity.
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Affiliation(s)
- Gerald Kooyman
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California
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McDonald BI, Ponganis PJ. Insights from venous oxygen profiles: oxygen utilization and management in diving California sea lions. ACTA ACUST UNITED AC 2014; 216:3332-41. [PMID: 23926312 DOI: 10.1242/jeb.085985] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The management and depletion of O2 stores underlie the aerobic dive capacities of marine mammals. The California sea lion (Zalophus californianus) presumably optimizes O2 store management during all dives, but approaches its physiological limits during deep dives to greater than 300 m depth. Blood O2 comprises the largest component of total body O2 stores in adult sea lions. Therefore, we investigated venous blood O2 depletion during dives of California sea lions during maternal foraging trips to sea by: (1) recording venous partial pressure of O2 (P(O2)) profiles during dives, (2) characterizing the O2-hemoglobin (Hb) dissociation curve of sea lion Hb and (3) converting the P(O2) profiles into percent Hb saturation (S(O2)) profiles using the dissociation curve. The O2-Hb dissociation curve was typical of other pinnipeds (P50=28±2 mmHg at pH 7.4). In 43% of dives, initial venous S(O2) values were greater than 78% (estimated resting venous S(O2)), indicative of arterialization of venous blood. Blood O2 was far from depleted during routine shallow dives, with minimum venous S(O2) values routinely greater than 50%. However, in deep dives greater than 4 min in duration, venous S(O2) reached minimum values below 5% prior to the end of the dive, but then increased during the last 30-60 s of ascent. These deep dive profiles were consistent with transient venous blood O2 depletion followed by partial restoration of venous O2 through pulmonary gas exchange and peripheral blood flow during ascent. These differences in venous O2 profiles between shallow and deep dives of sea lions reflect distinct strategies of O2 store management and suggest that underlying cardiovascular responses will also differ.
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Affiliation(s)
- Birgitte I McDonald
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, La Jolla, CA 92093-0204, USA.
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López-Cruz RI, Pérez-Milicua MB, Crocker DE, Gaxiola-Robles R, Bernal-Vertiz JA, de la Rosa A, Vázquez-Medina JP, Zenteno-Savín T. Purine nucleoside phosphorylase and xanthine oxidase activities in erythrocytes and plasma from marine, semiaquatic and terrestrial mammals. Comp Biochem Physiol A Mol Integr Physiol 2014; 171:31-5. [PMID: 24530799 DOI: 10.1016/j.cbpa.2014.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 01/29/2014] [Accepted: 02/03/2014] [Indexed: 01/23/2023]
Abstract
Purine nucleoside phosphorylase (PNP) and xanthine oxidase (XO) are key enzymes involved in the purine salvage pathway. PNP metabolizes purine bases to synthetize purine nucleotides whereas XO catalyzes the oxidation of purines to uric acid. In humans, PNP activity is reported to be high in erythrocytes and XO activity to be low in plasma; however, XO activity increases after ischemic events. XO activity in plasma of northern elephant seals has been reported during prolonged fasting and rest and voluntary associated apneas. The objective of this study was to analyze circulating PNP and XO activities in marine mammals adapted to tolerate repeated cycles of ischemia/reperfusion associated with diving (bottlenose dolphin, northern elephant seal) in comparison with semiaquatic (river otter) and terrestrial mammals (human, pig). PNP activities in plasma and erythrocytes, as well as XO activity in plasma, from all species were quantified by spectrophotometry. No clear relationship in circulating PNP or XO activity could be established between marine, semiaquatic and terrestrial mammals. Erythrocytes from bottlenose dolphins and humans are highly permeable to nucleosides and glucose, intraerythrocyte PNP activity may be related to a release of purine nucleotides from the liver. High-energy costs will probably mean a higher ATP degradation rate in river otters, as compared to northern elephant seals or dolphins. Lower erythrocyte PNP activity and elevated plasma XO activity in northern elephant seal could be associated with fasting and/or sleep- and dive-associated apneas.
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Affiliation(s)
- Roberto I López-Cruz
- Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, Baja California Sur, C.P. 23096, Mexico.
| | - Myrna Barjau Pérez-Milicua
- Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, Baja California Sur, C.P. 23096, Mexico.
| | - Daniel E Crocker
- Sonoma State University, Department of Biology, 1801 E. Cotati Ave., Rohnert Park, CA 94928, USA.
| | - Ramón Gaxiola-Robles
- Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, Baja California Sur, C.P. 23096, Mexico; Hospital General de Zona No.1. Instituto Mexicano del Seguro Social, La Paz, Baja California Sur, Mexico.
| | - Jaime A Bernal-Vertiz
- Cabo Dolphins, Paseo de la Marina 7A, Cabo San Lucas, Baja California Sur, C.P. 23410, Mexico.
| | - Alejandro de la Rosa
- Acuario de Veracruz A.C., Departamento de Mamíferos Acuáticos, Aves y Reptiles, Veracruz, Veracruz, Mexico.
| | - José P Vázquez-Medina
- Institute for Environmental Medicine, Perelman School of Medicine, University of Pennsylvania, 1 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104, USA.
| | - Tania Zenteno-Savín
- Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, Baja California Sur, C.P. 23096, Mexico.
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Nousek-McGregor AE, Miller CA, Moore MJ, Nowacek DP. Effects of body condition on buoyancy in endangered North Atlantic right whales. Physiol Biochem Zool 2013; 87:160-71. [PMID: 24457930 DOI: 10.1086/671811] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Buoyancy is an important consideration for diving marine animals, resulting in specific ecologically relevant adaptations. Marine mammals use blubber as an energy reserve, but because this tissue is also positively buoyant, nutritional demands have the potential to cause considerable variation in buoyancy. North Atlantic right whales Eubalaena glacialis are known to be positively buoyant as a result of their blubber, and the thickness of this layer varies considerably, but the effect of this variation on buoyancy has not been explored. This study compared the duration and rate of ascending and descending glides, recorded with an archival tag, with blubber thickness, measured with an ultrasound device, in free-swimming right whales. Ascending whales with thicker blubber had shorter portions of active propulsion and longer passive glides than whales with thinner blubber, suggesting that blubber thickness influences buoyancy because the buoyant force is acting in the same direction as the animal's movement during this phase. Whales with thinner layers also used similar body angles and velocities when traveling to and from depth, while those with thicker layers used shallower ascent angles but achieved higher ascent velocities. Such alterations in body angle may help to reduce the cost of transport when swimming against the force of buoyancy in a state of augmented positive buoyancy, which represents a dynamic response to reduce the energetic consequences of physiological changes. These results have considerable implications for any diving marine animal during periods of nutritional stress, such as during seasonal migrations and annual variations in prey availability.
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Affiliation(s)
- Anna E Nousek-McGregor
- Nicholas School for the Environment and Earth Sciences, Duke University Marine Laboratory, Beaufort, North Carolina 28516; 2Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543; 3Department of Electrical and Computer Engineering, Pratt School of Engineering, Duke University, Durham, North Carolina 27708
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Piscitelli MA, Raverty SA, Lillie MA, Shadwick RE. A review of cetacean lung morphology and mechanics. J Morphol 2013; 274:1425-40. [DOI: 10.1002/jmor.20192] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 06/25/2013] [Accepted: 08/05/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Marina A. Piscitelli
- Department of Zoology; University of British Columbia; Vancouver British Columbia Canada V6T 1Z4
| | - Stephen A. Raverty
- Department of Zoology; University of British Columbia; Vancouver British Columbia Canada V6T 1Z4
- Division of Plant and Animal Health; British Columbia Ministry of Agriculture; Abbotsford British Columbia Canada V3G 2M3
| | - Margo A. Lillie
- Department of Zoology; University of British Columbia; Vancouver British Columbia Canada V6T 1Z4
| | - Robert E. Shadwick
- Department of Zoology; University of British Columbia; Vancouver British Columbia Canada V6T 1Z4
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Abstract
We developed an automated method using depth and one axis of body acceleration data recorded by animal-borne data loggers to identify activities of penguins over long-term deployments. Using this technique, we evaluated the activity time budget of emperor penguins (n = 10) both in water and on sea ice during foraging trips in chick-rearing season. During the foraging trips, emperor penguins alternated dive bouts (4.8 ± 4.5 h) and rest periods on sea ice (2.5 ± 2.3 h). After recorder deployment and release near the colony, the birds spent 17.9 ± 8.4% of their time traveling until they reached the ice edge. Once at the ice edge, they stayed there more than 4 hours before the first dive. After the first dive, the mean proportions of time spent on the ice and in water were 30.8 ± 7.4% and 69.2 ± 7.4%, respectively. When in the water, they spent 67.9 ± 3.1% of time making dives deeper than 5 m. Dive activity had no typical diurnal pattern for individual birds. While in the water between dives, the birds had short resting periods (1.2 ± 1.7 min) and periods of swimming at depths shallower than 5 m (0.25 ± 0.38 min). When the birds were on the ice, they primarily used time for resting (90.3 ± 4.1% of time) and spent only 9.7 ± 4.1% of time traveling. Thus, it appears that, during foraging trips at sea, emperor penguins traveled during dives >5 m depth, and that sea ice was primarily used for resting. Sea ice probably provides refuge from natural predators such as leopard seals. We also suggest that 24 hours of sunlight and the cycling of dive bouts with short rest periods on sea ice allow emperor penguins to dive continuously throughout the day during foraging trips to sea.
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Affiliation(s)
- Shinichi Watanabe
- Faculty of Life Science and Biotechnology, Fukuyama University, Fukuyama, Hiroshima, Japan.
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Miller PJO, Biuw M, Watanabe YY, Thompson D, Fedak MA. Sink fast and swim harder! Round-trip cost-of-transport for buoyant divers. J Exp Biol 2012; 215:3622-30. [DOI: 10.1242/jeb.070128] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Efficient locomotion between prey resources at depth and oxygen at the surface is crucial for breath-hold divers to maximize time spent in the foraging layer, and thereby net energy intake rates. The body density of divers, which changes with body condition, determines the apparent weight (buoyancy) of divers, which may affect round-trip cost-of-transport (COT) between the surface and depth. We evaluated alternative predictions from external-work and actuator-disc theory of how non-neutral buoyancy affects round-trip COT to depth, and the minimum COT speed for steady-state vertical transit. Not surprisingly, the models predict that one-way COT decreases (increases) when buoyancy aids (hinders) one-way transit. At extreme deviations from neutral buoyancy, gliding at terminal velocity is the minimum COT strategy in the direction aided by buoyancy. In the transit direction hindered by buoyancy, the external-work model predicted that minimum COT speeds would not change at greater deviations from neutral buoyancy, but minimum COT speeds were predicted to increase under the actuator disc model. As previously documented for grey seals, we found that vertical transit rates of 36 elephant seals increased in both directions as body density deviated from neutral buoyancy, indicating that actuator disc theory may more closely predict the power requirements of divers affected by gravity than an external work model. For both models, minor deviations from neutral buoyancy did not affect minimum COT speed or round-trip COT itself. However, at body-density extremes, both models predict that savings in the aided direction do not fully offset the increased COT imposed by the greater thrusting required in the hindered direction.
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Affiliation(s)
- Patrick J. O. Miller
- Sea Mammal Research Unit, School of Biology, University of St Andrews, Fife KY16 9QQ, UK
| | - Martin Biuw
- Sea Mammal Research Unit, School of Biology, University of St Andrews, Fife KY16 9QQ, UK
| | - Yuuki Y. Watanabe
- National Institute of Polar Research, 10-3, Midori-cho, Tachikawa, Tokyo 190-8518, Japan
| | - Dave Thompson
- Sea Mammal Research Unit, School of Biology, University of St Andrews, Fife KY16 9QQ, UK
| | - Mike A. Fedak
- Sea Mammal Research Unit, School of Biology, University of St Andrews, Fife KY16 9QQ, UK
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McDonald BI, Ponganis PJ. Lung collapse in the diving sea lion: hold the nitrogen and save the oxygen. Biol Lett 2012; 8:1047-9. [PMID: 22993241 DOI: 10.1098/rsbl.2012.0743] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Lung collapse is considered the primary mechanism that limits nitrogen absorption and decreases the risk of decompression sickness in deep-diving marine mammals. Continuous arterial partial pressure of oxygen profiles in a free-diving female California sea lion (Zalophus californianus) revealed that (i) depth of lung collapse was near 225 m as evidenced by abrupt changes in during descent and ascent, (ii) depth of lung collapse was positively related to maximum dive depth, suggesting that the sea lion increased inhaled air volume in deeper dives and (iii) lung collapse at depth preserved a pulmonary oxygen reservoir that supplemented blood oxygen during ascent so that mean end-of-dive arterial was 74 ± 17 mmHg (greater than 85% haemoglobin saturation). Such information is critical to the understanding and the modelling of both nitrogen and oxygen transport in diving marine mammals.
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Affiliation(s)
- Birgitte I McDonald
- Center for Marine Biotechnology and Biomedicine, Scholander Hall, Scripps Institution of Oceanography, 9500 Gilman Drive no. 0204, La Jolla, CA 92093-0204, USA.
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Shiomi K, Sato K, Ponganis PJ. Point of no return in diving emperor penguins: is the timing of the decision to return limited by the number of strokes? ACTA ACUST UNITED AC 2012; 215:135-40. [PMID: 22162861 DOI: 10.1242/jeb.064568] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
At some point in a dive, breath-hold divers must decide to return to the surface to breathe. The issue of when to end a dive has been discussed intensively in terms of foraging ecology and behavioral physiology, using dive duration as a temporal parameter. Inevitably, however, a time lag exists between the decision of animals to start returning to the surface and the end of the dive, especially in deep dives. In the present study, we examined the decision time in emperor penguins under two different conditions: during foraging trips at sea and during dives at an artificial isolated dive hole. It was found that there was an upper limit for the decision-to-return time irrespective of dive depth in birds diving at sea. However, in a large proportion of dives at the isolated dive hole, the decision-to-return time exceeded the upper limit at sea. This difference between the decision times in dives at sea versus the isolated dive hole was accounted for by a difference in stroke rate. The stroke rates were much lower in dives at the isolated hole and were inversely correlated with the upper limit of decision times in individual birds. Unlike the decision time to start returning, the cumulative number of strokes at the decision time fell within a similar range in the two experiments. This finding suggests that the number of strokes, but not elapsed time, constrained the decision of emperor penguins to return to the surface. While the decision to return and to end a dive may be determined by a variety of ecological, behavioral and physiological factors, the upper limit to that decision time may be related to cumulative muscle workload.
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Affiliation(s)
- Kozue Shiomi
- International Coastal Research Center, Atmosphere and Ocean Research Institute, The University of Tokyo, 2-106-1 Akahama, Otsuchi, Iwate 028-1102, Japan.
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Williams CL, Sato K, Shiomi K, Ponganis PJ. Muscle energy stores and stroke rates of emperor penguins: implications for muscle metabolism and dive performance. Physiol Biochem Zool 2012; 85:120-33. [PMID: 22418705 DOI: 10.1086/664698] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In diving birds and mammals, bradycardia and peripheral vasoconstriction potentially isolate muscle from the circulation. During complete ischemia, ATP production is dependent on the size of the myoglobin oxygen (O(2)) store and the concentrations of phosphocreatine (PCr) and glycogen (Gly). Therefore, we measured PCr and Gly concentrations in the primary underwater locomotory muscle of emperor penguin and modeled the depletion of muscle O(2) and those energy stores under conditions of complete ischemia and a previously determined muscle metabolic rate. We also analyzed stroke rate to assess muscle workload variation during dives and evaluate potential limitations on the model. Measured PCr and Gly concentrations, 20.8 and 54.6 mmol kg(-1), respectively, were similar to published values for nondiving animals. The model demonstrated that PCr and Gly provide a large anaerobic energy store, even for dives longer than 20 min. Stroke rate varied throughout the dive profile, indicating muscle workload was not constant during dives as was assumed in the model. The stroke rate during the first 30 s of dives increased with increased dive depth. In extremely long dives, lower overall stroke rates were observed. Although O(2) consumption and energy store depletion may vary during dives, the model demonstrated that PCr and Gly, even at concentrations typical of terrestrial birds and mammals, are a significant anaerobic energy store and can play an important role in the emperor penguin's ability to perform long dives.
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Affiliation(s)
- Cassondra L Williams
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, California 92093-0204, USA.
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Ponganis PJ, Meir JU, Williams CL. In pursuit of Irving and Scholander: a review of oxygen store management in seals and penguins. J Exp Biol 2011; 214:3325-39. [DOI: 10.1242/jeb.031252] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
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 O2 stores that underlie the ADL. Therefore, in order to assess strategies of O2 store management, we review (a) the magnitude of O2 stores, (b) past studies of O2 store depletion and (c) our recent investigations of O2 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 O2 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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Affiliation(s)
- Paul J. Ponganis
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
| | - Jessica U. Meir
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Cassondra L. Williams
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, 92697, USA
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Knight K. PENGUINS PLAN DIVES. J Exp Biol 2011. [DOI: 10.1242/jeb.063255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Penguins dive without delay. Nature 2011. [DOI: 10.1038/476374d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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