skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Calibration-free technique for the measurement of oxygen saturation changes in muscles of marine mammals and its proof of concept
Title: Calibration-free technique for the measurement of oxygen saturation changes in muscles of marine mammals and its proof of concept
Marine mammals possess impressive breath-holding capabilities made possible by physiological adjustments during dives. Studying marine mammals in their natural environment unravels vital information about these physiological adjustments particularly when we can monitor altered dive behavior in response to stressful situations such as human-induced oceanic disturbances, presence of predators and altered prey distributions. An important indicator of physiological status during submergence is the change in oxygen saturation in the muscles and blood of these mammals. In this work, we aim to investigate oxygen storage and consumption in the muscles of free-diving elephant seals when exposed to disturbances such as sonar or predator sounds while they are at sea. Optical oxygen sensors are a mature technology with multiple medical applications that provide a way to measure oxygenation changes in biological tissues in a minimally invasive manner. While these sensors are well calibrated and readily available for humans, they are still inadequate for marine mammals primarily due to a very small number of test candidates and therefore little data is available for validation and calibration. We propose a probe geometry and associated mathematical model for measuring muscle oxygenation in seals based on near infrared diffuse transport with no need for calibration. A prototype based on this concept has been designed and tested on humans and rats. We use the test results to discuss the advantages and limitations of the approach. We also detail the constraints on size, sensor location, electronics, light source properties and detector characteristics posed by the unique biology of seals.  more » « less
Award ID(s):
1656312 1921742
PAR ID:
10105047
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
Proceedings SPIE 10489, Optical Biopsy XVI: Toward Real-Time Spectroscopic Imaging and Diagnosis
Volume:
10489D
Page Range / eLocation ID:
12
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Temperature)
    null (Ed.)
    The ability to maintain a high core body temperature is a defining characteristic of all mammals, yet their diverse habitats present disparate thermal challenges that have led to specialized adaptations. Marine mammals inhabit a highly conductive environment. Their thermoregulatory capabilities far exceed our own despite having limited avenues of heat transfer. Additionally, marine mammals must balance their thermoregulatory demands with those associated with diving (i.e. oxygen conservation), both of which rely on cardiovascular adjustments. This review presents the progress and novel efforts in investigating marine mammal thermoregulation, with a particular focus on the role of peripheral perfusion. Early studies in marine mammal thermal physiology were primarily performed in the laboratory and provided foundational knowledge through in vivo experiments and ex vivo measurements. However, the ecological relevance of these findings remains unknown because comparable efforts on free-ranging animals have been limited. We demonstrate the utility of biologgers for studying their thermal adaptations in the context in which they evolved. Our preliminary results from freely diving northern elephant seals (Mirounga angustirostris) reveal blubber’s dynamic nature and the complex interaction between thermoregulation and the dive response due to the dual role of peripheral perfusion. Further exploring the potential use of biologgers for measuring physiological variables relevant to thermal physiology in other marine mammal species will enhance our understanding of the relative importance of morphology, physiology, and behavior for thermoregulation and overall homeostasis. 
    more » « less
  2. ; ; ; ; (, Proceedings of the National Academy of Sciences)
    Significance The decline in extinction rates through geologic time is a well-established but enigmatic feature of the marine animal fossil record. We hypothesize that this trend is driven largely by secular changes in the oxygenation of the atmosphere and oceans, as physiological principles predict that marine animals would have been more vulnerable to ocean warming during intervals of geological time with limited atmospheric oxygenation. We test this at a global oceanographic scale by combining models of ocean biogeochemistry and animal physiology. We show that atmospheric oxygen exerts a first-order control on the simulated extinction vulnerability of marine animals, highlighting its likely importance in controlling extinction trends through geologic time. 
    more » « less
  3. (, Proceedings of the National Academy of Sciences of the United States of America)
    Fine audiovocal control is a hallmark of human speech production and depends on precisely coordinated muscle activity guided by sensory feedback. Little is known about shared audiovocal mechanisms between humans and other mammals. We hypothesized that real-time audiovocal control in bat echolocation uses the same computational principles as human speech. To test the prediction of this hypothesis, we applied state feedback control (SFC) theory to the analysis of call frequency adjustments in the echolocating bat, Hipposideros armiger. This model organism exhibits well-developed audiovocal control to sense its surroundings via echolocation. Our experimental paradigm was analogous to one implemented in human subjects. We measured the bats’ vocal responses to spectrally altered echolocation calls. Individual bats exhibited highly distinct patterns of vocal compensation to these altered calls. Our findings mirror typical observations of speech control in humans listening to spectrally altered speech. Using mathematical modeling, we determined that the same computational principles of SFC apply to bat echolocation and human speech, confirming the prediction of our hypothesis. 
    more » « less
  4. ; ; ; ; ; ; ; (, Frontiers in Marine Science)
    Animals that display plasticity in behavioral, ecological, and morphological traits are better poised to cope with environmental disturbances. Here, we examined individual plasticity and intraspecific variation in the morphometrics, movement patterns, and dive behavior of an enigmatic apex predator, the leopard seal ( Hydrurga leptonyx ). Satellite/GPS tags and time-depth recorders were deployed on 22 leopard seals off the Western Antarctic Peninsula. Adult female leopard seals were significantly larger (454±59 kg) and longer (302±11 cm) than adult males (302±22 kg, 276±11 cm). As females were 50% larger than their male counterparts, leopard seals are therefore one of the most extreme examples of female-biased sexual size dimorphism in marine mammals. Female leopard seals also spent more time hauled-out on land and ice than males. In the austral spring/summer, three adult female leopard seals hauled-out on ice for 10+ days, which likely represent the first satellite tracks of parturition and lactation for the species. While we found sex-based differences in morphometrics and haul-out durations, other variables, including maximum distance traveled and dive parameters, did not vary by sex. Regardless of sex, some leopard seals remained in near-shore habitats, traveling less than 50 kilometers, while other leopard seals traveled up to 1,700 kilometers away from the tagging location. Overall, leopard seals were short (3.0±0.7 min) and shallow (29±8 m) divers. However, within this general pattern, some individual leopard seals primarily used short, shallow dives, while others switched between short, shallow dives and long, deep dives. We also recorded the single deepest and longest dive made by any leopard seal—1, 256 meters for 25 minutes. Together, our results showcased high plasticity among leopard seals tagged in a single location. These flexible behaviors and traits may offer leopard seals, an ice-associated apex predator, resilience to the rapidly changing Southern Ocean. 
    more » « less
  5. ; ; ; ; ; ; ; (, Royal Society Open Science)
    Understanding the ontogeny of diving behaviour in marine megafauna is crucial owing to its influence on foraging success, energy budgets, and mortality. We compared the ontogeny of diving behaviour in two closely related species—northern elephant seals (Mirounga angustirostris, n= 4) and southern elephant seals (Mirounga leonina, n= 9)—to shed light on the ecological processes underlying migration. Although both species have similar sizes and behaviours as adults, we discovered that juvenile northern elephant seals have superior diving development, reaching 260 m diving depth in just 30 days, while southern elephant seals require 160 days. Similarly, northern elephant seals achieve dive durations of approximately 11 min on their first day of migration, while southern elephant seals take 125 days. The faster physiological maturation of northern elephant seals could be related to longer offspring dependency and post-weaning fast durations, allowing them to develop their endogenous oxygen stores. Comparison across both species suggests that weaned seal pups face a trade-off between leaving early with higher energy stores but poorer physiological abilities or leaving later with improved physiology but reduced fat stores. This trade-off might be influenced by their evolutionary history, which shapes their migration behaviours in changing environments over time. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email