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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. 

Abstract Most of the Ross Sea has been designated a marine protected area (MPA), proposed ‘to protect ecosystem structure and function’. To assess effectiveness, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) selected Adélie (Pygoscelis adeliae) and emperor (Aptenodytes forsteri) penguins, Weddell seals (Leptonychotes weddellii) and Antarctic toothfish (Dissostichus mawsoni) as ecosystem change ‘indicator species’. Stable for decades, penguin and seal populations increased during 1998–2018 to surpass historical levels, indicating that change in ecosystem structure and function is underway. We review historical impacts to population trends, decadal datasets of ocean climate and fishing pressure on toothfish. Statistical modelling for Adélie penguins and Weddell seals indicates that variability in climate factors and cumulative extraction of adult toothfish may explain these trends. These mesopredators, and adult toothfish, all prey heavily on Antarctic silverfish (Pleuragramma antarcticum). Toothfish removal may be altering intraguild predation dynamics, leading to competitive release of silverfish and contributing to penguin and seal population changes. Despite decades of ocean/weather change, increases in indicator species numbers around Ross Island only began once the toothfish fishery commenced. The rational-use, ecosystem-based viewpoint promoted by CCAMLR regarding toothfish management needs re-evaluation, including in the context of the Ross Sea Region MPA. 

This is the first study to determine the red blood cell lifespan in a marine mammal species. High concentrations of carbon monoxide (CO) were found in the blood of bottlenose dolphins and in the blood and breath of belugas compared with healthy humans. Red blood cell turnover accounted for these high levels in bottlenose dolphins, but there may be alternative mechanisms of endogenous CO production that are contributing to the CO concentrations observed in belugas. 

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. 

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 O 2 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)’. 

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 PO2s 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 PO2s 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 PO2s 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. 

Anatomical and physiological adaptations of animals to extreme environments provide insight into basic physiological principles and potential therapies for human disease. In that regard, the diving physiology of marine mammals and seabirds is especially relevant to pulmonary and cardiovascular function, and to the pathology and potential treatment of patients with hypoxaemia and/or ischaemia. This review highlights past and recent progress in the field of comparative diving physiology with emphasis on its potential relevance to human medicine. 

In this paper, we introduce a creative pipeline to incorporate physiological and behavioral data from contemporary marine mammal research into data-driven animations, leveraging functionality from industry tools and custom scripts to promote scientific insights, public awareness, and conservation outcomes. Our framework can flexibly transform data describing animals’ orientation, position, heart rate, and swimming stroke rate to control the position, rotation, and behavior of 3D models, to render animations, and to drive data sonification. Additionally, we explore the challenges of unifying disparate datasets gathered by an interdisciplinary team of researchers, and outline our design process for creating meaningful data visualization tools and animations. As part of our pipeline, we clean and process raw acceleration and electrophysiological signals to expedite complex multi-stream data analysis and the identification of critical foraging and escape behaviors. We provide details about four animation projects illustrating marine mammal datasets. These animations, commissioned by scientists to achieve outreach and conservation outcomes, have successfully increased the reach and engagement of the scientific projects they describe. These impactful visualizations help scientists identify behavioral responses to disturbance, increase public awareness of human-caused disturbance, and help build momentum for targeted conservation efforts backed by scientific evidence.