A possible mechanism for acoustic triggering of decompression sickness symptoms in deep-diving marine mammals

2005 ◽  
Author(s):  
J.R. Potter
Keyword(s):  
Marine Mammals ◽  
Decompression Sickness ◽  
Deep Diving

scholarly journals Lung collapse in the diving sea lion: hold the nitrogen and save the oxygen

2012 ◽  
Vol 8 (6) ◽  
pp. 1047-1049 ◽  
Author(s):  
Birgitte I. McDonald ◽  
Paul J. Ponganis
Keyword(s):  
Marine Mammals ◽  
Decompression Sickness ◽  
Dive Depth ◽  
Nitrogen Absorption ◽  
Lung Collapse ◽  
Sea Lion ◽  
California Sea Lion ◽  
Deep Diving ◽  
Air Volume ◽  
Abrupt Changes

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.

scholarly journals Application of Multifrequency Bioelectrical Impedance Analysis Method for the Detection of Dehydration Status in Professional Divers

Medicina ◽  
2012 ◽  
Vol 48 (4) ◽  
pp. 29 ◽  
Author(s):  
Sermin Sengun ◽  
Atilla Uslu ◽  
Salih Aydin
Keyword(s):  
Bioelectrical Impedance Analysis ◽  
Decompression Sickness ◽  
Bioelectrical Impedance ◽  
Impedance Analysis ◽  
Extracellular Water ◽  
Analysis Method ◽  
Fluid Shift ◽  
Predisposing Factor ◽  
Deep Diving ◽  
Total Body

Background and Objective. The level of dehydration has been known to be a predisposing factor for the development of decompression sickness in divers. The aim of this study was to determine the level of dehydration in divers who dove with heliox and to determine whether the source of this dehydration was intracellular and/or extracellular by means of multifrequency bioelectrical impedance analysis (MF-BIA). Material and Methods. Eleven male professional divers were enrolled in the study. In order to determine the level of dehydration, MF-BIA was carried out (at 5, 50, and 100 kHz) and capillary hematocrit (Hct) was measured two times: one before diving and the other after leaving the pressure room. Results. When prediving and postdiving parameters were compared, significant increases in the resistance at 5 kHz (P<0.001), 50 kHz, (P<0.001), and 100 kHz (P<0.01) and Hct (P<0.01) were observed after the diving. Similarly, a statistically significant fluid shift was found: total body water, –1.30 L (P<0.001), extracellular water, –0.85 L (P<0.001); and intracellular water, –0.45 L (P=0.011). Conclusions. Our results showed that mild dehydration occurred both in the intracellular and extracellular compartments in divers after deep diving. This study also indicates that MF-BIA could be a reliable new method for determining the dehydration status in divers.

A Review of the Effects of Seismic Surveys on Marine Mammals

2003 ◽  
Vol 37 (4) ◽  
pp. 16-34 ◽  
Author(s):  
Jonathan Gordon ◽  
Douglas Gillespie ◽  
John Potter ◽  
Alexandros Frantzis ◽  
Mark P. Simmonds ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Decompression Sickness ◽  
Prey Availability ◽  
Biological Effects ◽  
Biological Significance ◽  
Hearing Threshold ◽  
Seismic Signal ◽  
Limited Range ◽  
Physiological Effects ◽  
Air Gun

This review highlights significant gaps in our knowledge of the effects of seismic air gun noise on marine mammals. Although the characteristics of the seismic signal at different ranges and depths and at higher frequencies are poorly understood, and there are often insufficient data to identify the appropriate acoustic propagation models to apply in particular conditions, these uncertainties are modest compared with those associated with biological factors. Potential biological effects of air gun noise include physical/physiological effects, behavioral disruption, and indirect effects associated with altered prey availability. Physical/physiological effects could include hearing threshold shifts and auditory damage as well as non-auditory disruption, and can be directly caused by sound exposure or the result of behavioral changes in response to sounds, e.g. recent observations suggesting that exposure to loud noise may result in decompression sickness. Direct information on the extent to which seismic pulses could damage hearing are difficult to obtain and as a consequence the impacts on hearing remain poorly known. Behavioral data have been collected for a few species in a limited range of conditions. Responses, including startle and fright, avoidance, and changes in behavior and vocalization patterns, have been observed in baleen whales, odontocetes, and pinnipeds and in some case these have occurred at ranges of tens or hundreds of kilometers. However, behavioral observations are typically variable, some findings are contradictory, and the biological significance of these effects has not been measured. Where feeding, orientation, hazard avoidance, migration or social behavior are altered, it is possible that populations could be adversely affected. There may also be serious long-term consequences due to chronic exposure, and sound could affect marine mammals indirectly by changing the accessibility of their prey species. A precautionary approach to management and regulation must be recommended. While such large degrees of uncertainty remain, this may result in restrictions to operational practices but these could be relaxed if key uncertainties are clarified by appropriate research.

VISUAL PIGMENT SENSITIVITY IN THREE DEEP DIVING MARINE MAMMALS

2002 ◽  
Vol 18 (1) ◽  
pp. 275-281 ◽  
Author(s):  
K. D. Southall ◽  
G. W. Oliver ◽  
J. W. Lewis ◽  
B. J. Boeuf ◽  
D. H. Levenson
Keyword(s):  
Visual Pigment ◽  
Marine Mammals ◽  
Deep Diving

scholarly journals Deadly diving? Physiological and behavioural management of decompression stress in diving mammals

2011 ◽  
Vol 279 (1731) ◽  
pp. 1041-1050 ◽  
Author(s):  
S. K. Hooker ◽  
A. Fahlman ◽  
M. J. Moore ◽  
N. Aguilar de Soto ◽  
Y. Bernaldo de Quirós ◽  
...  
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
Multiple Stressors ◽  
Decompression Sickness ◽  
Tissue Injury ◽  
Bubble Formation ◽  
Gas Bubbles ◽  
Breath Hold ◽  
Technological Advances ◽  
Measured Time

Decompression sickness (DCS; ‘the bends’) is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N 2 ) loading during dives. However, recent observations have shown that gas bubbles may form and tissue injury may occur in marine mammals under certain circumstances. Gas kinetic models based on measured time-depth profiles further suggest the potential occurrence of high blood and tissue N 2 tensions. We review evidence for gas-bubble incidence in marine mammal tissues and discuss the theory behind gas loading and bubble formation. We suggest that diving mammals vary their physiological responses according to multiple stressors, and that the perspective on marine mammal diving physiology should change from simply minimizing N 2 loading to management of the N 2 load . This suggests several avenues for further study, ranging from the effects of gas bubbles at molecular, cellular and organ function levels, to comparative studies relating the presence/absence of gas bubbles to diving behaviour. Technological advances in imaging and remote instrumentation are likely to advance this field in coming years.

Spectral-tuning mechanisms of marine mammal rhodopsins and correlations with foraging depth

2000 ◽  
Vol 17 (5) ◽  
pp. 781-788 ◽  
Author(s):  
JEFFRY I. FASICK ◽  
PHYLLIS R. ROBINSON
Keyword(s):  
Amino Acid ◽  
Marine Mammal ◽  
Molecular Basis ◽  
Marine Mammals ◽  
Visual Pigments ◽  
Amino Acid Substitutions ◽  
Spectral Tuning ◽  
Long Wavelength ◽  
Terrestrial Mammals ◽  
Deep Diving

It has been observed that deep-foraging marine mammals have visual pigments that are blue shifted in terms of their wavelength of maximal absorbance (λmax) when compared to analogous pigments from terrestrial mammals. The mechanisms underlying the spectral tuning of two of these blue-shifted pigments have recently been elucidated and depend on three amino acid substitutions (83Asn, 292Ser, and 299Ser) in dolphin rhodopsin, but only one amino acid substitution (308Ser) in the dolphin long-wavelength-sensitive pigment. The objective of this study was to investigate the molecular basis for changes in the spectral sensitivity of rod visual pigments from seven distantly related marine mammals. The results show a relationship between blue-shifted rhodopsins (λmax ≤ 490 nm), deep-diving foraging behavior, and the substitutions 83Asn and 292Ser. Species that forage primarily near the surface in coastal habitats have a rhodopsin with a λmax similar to that of terrestrial mammals (500 nm) and possess the substitutions 83Asp and 292Ala, identical to rhodopsins from terrestrial mammals.

scholarly journals Comparative genomics provides insights into the aquatic adaptations of mammals

2021 ◽  
Vol 118 (37) ◽  
pp. e2106080118
Author(s):  
Yuan Yuan ◽  
Yaolei Zhang ◽  
Peijun Zhang ◽  
Chang Liu ◽  
Jiahao Wang ◽  
...  
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
Published Data ◽  
Aquatic Life ◽  
Genomic Variations ◽  
Deep Diving ◽  
Brown Adipose ◽  
Timing Pattern ◽  
Genome Assemblies ◽  
High Quality Genome

The ancestors of marine mammals once roamed the land and independently committed to an aquatic lifestyle. These macroevolutionary transitions have intrigued scientists for centuries. Here, we generated high-quality genome assemblies of 17 marine mammals (11 cetaceans and six pinnipeds), including eight assemblies at the chromosome level. Incorporating previously published data, we reconstructed the marine mammal phylogeny and population histories and identified numerous idiosyncratic and convergent genomic variations that possibly contributed to the transition from land to water in marine mammal lineages. Genes associated with the formation of blubber (NFIA), vascular development (SEMA3E), and heat production by brown adipose tissue (UCP1) had unique changes that may contribute to marine mammal thermoregulation. We also observed many lineage-specific changes in the marine mammals, including genes associated with deep diving and navigation. Our study advances understanding of the timing, pattern, and molecular changes associated with the evolution of mammalian lineages adapting to aquatic life.

Decompression sickness in the rat following a dive on trimix: recompression therapy with oxygen vs. heliox and oxygen

2007 ◽  
Vol 102 (4) ◽  
pp. 1324-1328 ◽  
Author(s):  
R. Arieli ◽  
P. Svidovsky ◽  
A. Abramovich
Keyword(s):  
High Pressure ◽  
Body Mass ◽  
Rat Model ◽  
Death Rate ◽  
Decompression Sickness ◽  
Hyperbaric Chamber ◽  
Permanent Disability ◽  
Hyperbaric Treatment ◽  
Deep Diving ◽  
Time Required

Trimix (a mixture of helium, nitrogen, and oxygen) has been used in deep diving to reduce the risk of high-pressure nervous syndrome during compression and the time required for decompression at the end of the dive. There is no specific recompression treatment for decompression sickness (DCS) resulting from trimix diving. Our purpose was to validate a rat model of DCS on decompression from a trimix dive and to compare recompression treatment with oxygen and heliox (helium-oxygen). Rats were exposed to trimix in a hyperbaric chamber and tested for DCS while walking in a rotating wheel. We first established the experimental model, and then studied the effect of hyperbaric treatment on DCS: either hyperbaric oxygen (HBO) (1 h, 280 kPa oxygen) or heliox-HBO (0.5 h, 405 kPa heliox 50%-50% followed by 0.5 h, 280 kPa oxygen). Exposure to trimix was conducted at 1,110 kPa for 30 min, with a decompression rate of 100 kPa/min. Death and most DCS symptoms occurred during the 30-min period of walking. In contrast to humans, no permanent disability was found in the rats. Rats with a body mass of 100–150 g suffered no DCS. The risk of DCS in rats weighing 200–350 g increased linearly with body mass. Twenty-four hours after decompression, death rate was 40% in the control animals and zero in those treated immediately with HBO. When treatment was delayed by 5 min, death rate was 25 and 20% with HBO and heliox, respectively.

scholarly journals How Do Marine Mammals Manage and Usually Avoid Gas Emboli Formation and Gas Embolic Pathology? Critical Clues From Studies of Wild Dolphins

2021 ◽  
Vol 8 ◽  
Author(s):  
Andreas Fahlman ◽  
Michael J. Moore ◽  
Randall S. Wells
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Gas Bubbles ◽  
Theoretical Models ◽  
Anatomy And Physiology ◽  
Terrestrial Mammals ◽  
Deep Diving ◽  
Cardiorespiratory Function ◽  
Sarasota Bay ◽  
Excised Tissues

Decompression theory has been mainly based on studies on terrestrial mammals, and may not translate well to marine mammals. However, evidence that marine mammals experience gas bubbles during diving is growing, causing concern that these bubbles may cause gas emboli pathology (GEP) under unusual circumstances. Marine mammal management, and usual avoidance, of gas emboli and GEP, or the bends, became a topic of intense scientific interest after sonar-exposed, mass-stranded deep-diving whales were observed with gas bubbles. Theoretical models, based on our current understanding of diving physiology in cetaceans, predict that the tissue and blood N2 levels in the bottlenose dolphin (Tursiops truncatus) are at levels that would result in severe DCS symptoms in similar sized terrestrial mammals. However, the dolphins appear to have physiological or behavioral mechanisms to avoid excessive blood N2 levels, or may be more resistant to circulating bubbles through immunological/biochemical adaptations. Studies on behavior, anatomy and physiology of marine mammals have enhanced our understanding of the mechanisms that are thought to prevent excessive uptake of N2. This has led to the selective gas exchange hypothesis, which provides a mechanism how stress-induced behavioral change may cause failure of the normal physiology, which results in excessive uptake of N2, and in extreme cases may cause formation of symptomatic gas emboli. Studies on cardiorespiratory function have been integral to the development of this hypothesis, with work initially being conducted on excised tissues and cadavers, followed by studies on anesthetized animals or trained animals under human care. These studies enabled research on free-ranging common bottlenose dolphins in Sarasota Bay, FL, and off Bermuda, and have included work on the metabolic and cardiorespiratory physiology of both shallow- and deep-diving dolphins and have been integral to better understand how cetaceans can dive to extreme depths, for long durations.

Myoglobin in pelagic small cetaceans

1999 ◽  
Vol 202 (3) ◽  
pp. 227-236 ◽  
Author(s):  
M.L. Dolar ◽  
P. Suarez ◽  
P.J. Ponganis ◽  
G.L. Kooyman
Keyword(s):  
Muscle Mass ◽  
Marine Mammals ◽  
Killer Whale ◽  
Stomach Contents ◽  
Abdominal Muscle ◽  
Mass Composition ◽  
Sulu Sea ◽  
Deep Diving ◽  
Spinner Dolphins ◽  
Few Data

Although myoglobin (Mb) is considered to contribute significantly to the oxygen and diving capacity of marine mammals, few data are available for cetaceans. Cetacean by-catch in the tuna driftnet fisheries in the Sulu Sea, Philippines, afforded the opportunity to examine Mb content and distribution, and to determine muscle mass composition, in Fraser's (Lagenodelphis hosei) and spinner (Stenella longirostris) dolphins and a pygmy killer whale (Feresa attenuata). Age was estimated by body length determination. Stomach contents were analyzed for the presence or absence of milk and solid foods. It was hypothesized (a) that Mb concentration ([Mb]) would be higher in Fraser's and spinner dolphins than in other small cetaceans because of the known mesopelagic distribution of their prey, (b) that [Mb] would vary among different muscles according to function during diving, and (c) that [Mb] would increase with age during development. The results were as follows. (1) Myoglobin concentrations of the longissimus muscle in adult Fraser's (6.8-7.2 g 100 g-1 muscle) and spinner (5–6 g 100 g-1 muscle) dolphins and in an immature pygmy killer whale (5.7 g 100 g-1 muscle) were higher than those reported previously for small cetaceans. (2) [Mb] varied significantly among the different muscle types in adult dolphins but not in calves; in adults, swimming muscles had significantly higher [Mb] than did non-swimming muscles, contained 82–86 % of total Mb, and constituted 75–80 % of total muscle mass. (3) Myoglobin concentrations in Fraser's and spinner dolphins increased with size and age and were 3–4 times greater in adults than in calves. The high Mb concentrations measured in the primary locomotory muscles of these pelagic dolphins are consistent with the known mesopelagic foraging behaviour of Fraser's and spinner dolphins and suggest that the pygmy killer whale is also a deep-diving species. The high Mb concentrations in epaxial, hypaxial and abdominal muscle groups also support the primary locomotory functions suggested for these muscles in other anatomical studies. As in other species, the increase in [Mb] during development probably parallels the development of diving capacity.

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