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At least 19 recordsLinked to original sources
PubMed2003

Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus.

We investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (ADL) of platypuses (Ornithorhynchus anatinus) living at a sub-alpine Tasmanian lake. Individual platypuses were equipped with combined data logger-transmitter packages measuring dive depth. Mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. Mean surface duration was 10.1 s. Mean dive depth was 1.28 m with a maximum of 8.77 m. Platypuses performed up to 1600 dives per foraging trip with a mean of 75 dives per hour. ADL was estimated by consideration of post-dive surface intervals vs. dive durations. Only 15% of all dives were found to exceed the estimated ADL of 40 s, indicating mainly aerobic diving in the species. Foraging platypuses followed a model of optimised recovery time, the optimal breathing theory. Total bottom duration or total foraging duration per day is proposed as a useful indicator of foraging efficiency and hence habitat quality in the species.

Animals↗
PubMed2001

The diving behaviour of green turtles undertaking oceanic migration to and from Ascension Island: dive durations, dive profiles and depth distribution.

Satellite telemetry was used to record the submergence duration of green turtles (Chelonia mydas) as they migrated from Ascension Island to Brazil (N=12 individuals) while time/depth recorders (TDRs) were used to examine the depth distribution and dive profiles of individuals returning to Ascension Island to nest after experimental displacement (N=5 individuals). Satellite telemetry revealed that most submergences were short (<5 min) but that some submergences were longer (>20 min), particularly at night. TDRs revealed that much of the time was spent conducting short (2-4 min), shallow (approximately 0.9-1.5 m) dives, consistent with predictions for optimisation of near-surface travelling, while long (typically 20-30 min), deep (typically 10-20 m) dives had a distinctive profile found in other marine reptiles. These results suggest that green turtles crossing the Atlantic do not behave invariantly, but instead alternate between periods of travelling just beneath the surface and diving deeper. These deep dives may have evolved to reduce silhouetting against the surface, which would make turtles more susceptible to visual predators such as large sharks.

Animal Migration↗
PubMed2001

[Diving medicine aspects in otorhinolaryngology. II. Diving-specific illnesses and dysfunctions as well as assessment for diving fitness].

Scuba diving with compressed air has become a recreational sport that can be performed at all stages of adulthood. The human body including all gas-filled cavities are exposed to an increased ambient pressure during a dive. In the present review article, specific aspects of diving related disorders are that are of importance in the otolaryngology field are presented and discussed: the multitude of causes for divers' vertigo and the so called divers ear. Furthermore, useful recommendations in the assessment of physical fitness for diving are presented. This review will provide a background and foundation for both, an adequate treatment of these diseases and a critical and responsible health education of the diver.

Caloric Tests↗
PubMed2003

Bleomycin and scuba diving: to dive or not to dive?

Bleomycin is to treat patients with testicular cancer and lymphoma. Bleomycin can bind to DNA and chelate iron. The resulting complex can form an intermediate capable of interacting with oxygen to produce reactive oxygen species, particularly superoxide. Administrating high-inspired oxygen concentrations (e.g. during anaesthesia or acute illness) has been reported to exacerbate pulmonary injury. The duration of risk after bleomycin chemotherapy is unknown. Here we discuss our advice to a young male patient, who was successfully treated with bleomycin for testicular cancer, concerning the safety to return to scuba diving. Since scuba divers are exposed to high partial oxygen pressures (depending on the depth of the dive) we discouraged this patient from resuming scuba diving.

Adult↗
PubMed2002

Pharmacological blockade of the dive response: effects on heart rate and diving behaviour in the harbour seal (Phoca vitulina).

While diving, harbour seals (Phoca vitulina) manage their oxygen stores through cardiovascular adjustments, including bradycardia, a concurrent reduction in cardiac output, and peripheral vasoconstriction. At the surface, post-dive tachycardia facilitates rapid reloading of oxygen stores. Although harbour seals can tolerate >20 min of submergence, the majority of their natural dives are only 2-6 min and are usually followed by surface intervals that are <1 min, so they spend approximately 80% of their time submerged. Given that harbour seals meet their ecological needs through repetitive short aerobic dives, we were interested in the functional role, if any, of the dive response during these short dives. During voluntary diving in an 11 m deep tank, the cardiovascular responses to submergence of five harbour seals were manipulated using specific pharmacological antagonists, and the effects on diving behaviour were observed. Effects of pharmacological blockade on heart rate were also examined to assess the autonomic control of heart rate during voluntary diving. Heart rate was recorded using subcutaneous electrodes and data loggers, while diving behaviour was monitored using a video camera. The muscarinic blocker methoctramine blocked diving bradycardia, the alpha-adrenergic blocker prazosin blocked diving vasoconstriction, and the beta-adrenergic blocker metoprolol blocked post-dive tachycardia. Heart-rate analysis indicated that diving bradycardia is primarily modulated by the vagus, while post-dive tachycardia results from parasympathetic withdrawal as well as increased sympathetic stimulation of the heart. None of the pharmacological blockers had any effect on average dive or surface interval duration. Seals maintained a high percentage of time spent diving in all treatments. Thus, harbour seals do not appear to need the dive response during short dives in order to maintain an efficient dive strategy.

Adrenergic alpha-Antagonists↗
PubMed2001

The diving behavior of blue and fin whales: is dive duration shorter than expected based on oxygen stores?

Many diving seabirds and marine mammals have been found to regularly exceed their theoretical aerobic dive limit (TADL). No animals have been found to dive for durations that are consistently shorter than their TADL. We attached time-depth recorders to 7 blue whales and 15 fin whales (family Balaenopteridae). The diving behavior of both species was similar, and we distinguished between foraging and traveling dives. Foraging dives in both species were deeper, longer in duration and distinguished by a series of vertical excursions where lunge feeding presumably occurred. Foraging blue whales lunged 2.4 (+/-1.13) times per dive, with a maximum of six times and average vertical excursion of 30.2 (+/-10.04) m. Foraging fin whales lunged 1.7 (+/-0.88) times per dive, with a maximum of eight times and average vertical excursion of 21.2 (+/-4.35) m. The maximum rate of ascent of lunges was higher than the maximum rate of descent in both species, indicating that feeding lunges occurred on ascent. Foraging dives were deeper and longer than non-feeding dives in both species. On average, blue whales dived to 140.0 (+/-46.01) m and 7.8 (+/-1.89) min when foraging, and 67.6 (+/-51.46) m and 4.9 (+/-2.53) min when not foraging. Fin whales dived to 97.9 (+/-32.59) m and 6.3 (+/-1.53) min when foraging and to 59.3 (+/-29.67) m and 4.2 (+/-1.67) min when not foraging. The longest dives recorded for both species, 14.7 min for blue whales and 16.9 min for fin whales, were considerably shorter than the TADL of 31.2 and 28.6 min, respectively. An allometric comparison of seven families diving to an average depth of 80-150 m showed a significant relationship between body mass and dive duration once Balaenopteridae whales, with a mean dive duration of 6.8 min, were excluded from the analysis. Thus, the short dive durations of blue whales and fin whales cannot be explained by the shallow distribution of their prey. We propose instead that short duration diving in large whales results from either: (1) dispersal behavior of prey; or (2) a high energetic cost of foraging.

Animals↗
PubMed1999

[Prospective lung function determination using an electronic miniature spirometer for detection of acute obstructive respiratory changes in diving students during occupational diving training].

BACKGROUND: Changes in lung function have been shown in experienced divers. The purpose of this study was to measure the pulmonary function of diving trainees who were not exposed to a hyperbaric environment before. METHODS: We measured the lung function in a sample of fifteen randomized selected young healthy non-smoking diving trainees parallel to fourteen open water dives. Five subjects used common compressed air diving apparatuses (breathing gas: 21% O2/78% N2) and ten subjects used closed circuit diving apparatuses (breathing gas compositions depended to the diving depths; 24 m: 60% O2/40% N2, 42 m: 40% O2/60% N2, 54 m: 32.5% O2/67.5% N2). The values (FVC, FEV1, PEF, MEF 25, MEF 50, MEF 75) were obtained by an electronic miniature-spirometer directly before descent, upon surfacing, and after one hour and four hours. RESULTS: The lung function values of the subjects who used compressed air showed no relevant impairment of lung function after the diving exposures. Significant (p < 0.05) post dive lung function reductions (FVC, FEV1, PEF, MEF 25, MEF 50, MEF 75), were evident in subjects using closed circuit diving apparatuses, after deep dives and shallow water dives. CONCLUSIONS: The decreased lung function of the used diving apparatuses. The impaired lung functions in subjects using closed circuit diving apparatuses may be induced by a subclinical lung edema generated by pressure differences between breathing gas and thorax tissues as well as the influences of soda-lime dust. Compared to compressed air diving the significantly increased oxygen partial pressures (p < 0.001) in closed circuit diving apparatuses may be an additional reason for the reversible airway obstructions.

Adult↗
PubMed1997

Decompression sickness from saturation diving: a case control study of some diving exposure characteristics.

A comprehensive computerized database of diving activity for a Norwegian offshore diving contractor [Stolt-Nielsen Seaway (SNS)] covering the years 1983-1990 has been established. The database contains detailed dive information about 12,087 surface-oriented and 2,622 saturation dives. During this period a majority of the divers were permanently employed. Preliminary analysis had suggested that decompression sickness (DCS) might be the result of exposure to factors causing pathophysiologic effects which accumulate over the course of a single dive or a series of dives. This concept evolved into the HADES (Highest Accumulated Decompression Score) theory which assumes that DCS is predictable once the underlying exposure factors are understood. The incidence of DCS among the SNS divers from saturation diving in the North Sea was studied by use of a "nested" case-control design. Twenty-one case dives (i.e., dives where DCS occurred) were compared with 41 randomly selected control dives. For these dives, several saturation dive characteristics were established. The relative pressure change between maximum and minimum storage depths was significantly greater among the cases. For each 1% increase in the relative pressure change there was a 5% increase in the probability of a saturation dive resulting in DCS. Significantly more cases than controls performed a saturation dive with more than one storage depth, and the data suggested that there were more and greater ascending and descending changes in storage depth conditions among the affected divers.

Case-Control Studies↗
PubMed1985

Free and forced diving in ducks: habituation of the initial dive response.

Response habituation in pekin ducks was observed during a study of the early phase of the dive response. This is interpreted as the orienting response and strongly suggests higher CNS influence in the initial phase of the forced immersion heart rate response. Repeated forced dives (20-30 s) of restrained ducks were performed with 40 s recovery period between dives. During the first dives, the ducks' heart rates fell 69% (272 +/- 8 to 83 +/- 32 beats X min-1, means +/- SE) of pre-dive values. The extent of this bradycardia decreased progressively as the dives were repeated. After 60 dives, the heart rates dropped by only 29% (248 +/- 3 to 177 +/- 25 beats X min-1 for pre-dive value). Voluntary diving of the ducks, lasting 5-20 s, caused no diving bradycardia. They showed breathing tachycardia which caused a 25% increase in heart rates above diving level (160 +/- 5 to 200 +/- 12 beats X min-1).

Animals↗
PubMed2002

Oxygen uptake during post dive recovery in a diving bird Aythya fuligula: implications for optimal foraging models.

The rate of oxygen uptake at the surface between dives was measured for four tufted ducks, Aythya fuligula, during bouts of foraging dives to a depth of 1.8 m. The ducks surfaced into a respirometer box after each dive so that the rate of oxygen uptake ((O(2))) could be measured. (O(2)) decreased over time at the surface and there was a particularly rapid phase of oxygen uptake for approximately the first 3s. The specific shape of the oxygen uptake curve is dependent upon the duration of the preceding dive. The uptake curve after longer dives was significantly steeper during the first 3s at the surface than after shorter dives, although (O(2)) after the first 3s was not significantly different between these two dive duration bins. Thus, the mean total oxygen uptake (V(O(2))) was higher after surface periods following longer dives. Due to the high (O(2)) during the initial part of the surface period, the curve associated with longer dives was statistically biphasic, with the point of inflection at 3.3s. The curve for shorter dives was not statistically biphasic. The birds may increase their respiratory frequency during the first 3s after longer dives, producing the increased (O(2)), which would enable the birds to resaturate their oxygen stores more rapidly in response to the increased oxygen depletion of the longer submergence time.

Animals↗
PubMed1989

[Diving profiles and work loads of fishermen's "Oikomi Gyoho" diving].

Diving profiles of fishermen divers in the Izu Islands were investigated and recorded by DDR (Diving Data Recorder). Consumed air volume during diving work was also checked in each dive and the work load was measured by VO2 during diving. It was recognized that divers repeatedly experienced extreme descents and ascents, that were accompanied by increases of oxygen consumption. This suggested that the load of their work was far beyond that of sports divers. The particular diving method used, called the "Oikomi Gyoho method" is to repeatedly dive several times to catch fish. Each bottom (diving) time is rather short and the dept changes from deeper to shallower areas gradually. This profile is considered to be a safe diving method for the prevention of DCS (Decompression Sickness). However, stopping for decompression during ascent is sometimes required to prevent DCS according to analysis of the diving profiles. It is pointed out that the risk of DCS still remains with this diving method.

Decompression Sickness↗
PubMedDate not supplied

Body oxygen stores, aerobic dive limits, and the diving abilities of juvenile and adult muskrats (Ondatra zibethicus).

Intraspecific variability in body oxygen reserves, muscle buffering capacity, diving metabolic rate, and diving behavior were examined in recently captured juvenile and adult muskrats. Allometric scaling exponents for lung (b=1.04), blood (b=0.91), and total body oxygen storage capacity (b=1.09) did not differ from unity. The concentration of skeletal muscle myoglobin scaled positively with mass in 254-600-g juveniles (b=1.63) but was mass-independent in larger individuals. Scaling exponents for diving metabolic rate and calculated aerobic dive limit (ADL) were 0.74 and 0.37, respectively. Contrary to allometric predictions, we found no evidence that the diving abilities of muskrats increased with age or body size. Juveniles aged 1-2 mo exhibited similar dive times but dove more frequently than summer-caught adults. Average and cumulative dive times and dive&rcolon;surface ratios were highest for fall- and winter-caught muskrats. Total body oxygen reserves were greatest in winter, mainly due to an increase in blood oxygen storage capacity. The buffering capacity of the hind limb swimming muscles also was highest in winter-caught animals. Several behavioral indicators of dive performance, including average and maximum duration of voluntary dives, varied positively with blood hemoglobin and muscle myoglobin concentration of muskrats. However, none of the behavioral measures were strongly correlated with the total body oxygen reserves or ADLs derived for these same individuals.

Adaptation, Physiological↗
PubMed1992

Metabolic rates of freely diving Weddell seals: correlations with oxygen stores, swim velocity and diving duration.

The metabolic rates of freely diving Weddell seals were measured using modern methods of on-line computer analysis coupled to oxygen consumption instrumentation. Oxygen consumption values were collected during sleep, resting periods while awake and during diving periods with the seals breathing at the surface of the water in an experimental sea-ice hole in Antarctica. Oxygen consumption during diving was not elevated over resting values but was statistically about 1.5 times greater than sleeping values. The metabolic rate of diving declined with increasing dive duration, but there was no significant difference between resting rates and rates in dives lasting up to 82 min. Swimming speed, measured with a microprocessor velocity recorder, was constant in each animal. Calculations of the aerobic dive limit of these seals were made from the oxygen consumption values and demonstrated that most dives were within this theoretical limit. The results indicate that the cost of diving is remarkably low in Weddell seals relative to other diving mammals and birds.

Animals↗
PubMed1997

Aetiology and occurrence of diving injuries. A review of diving safety.

This paper examines multifaceted aspects of diving entries into water which are the cause of many critical injuries (costed at $A150 million) and therefore have important safety ramifications. Wedge and compression fractures are most commonly found in the cervical area of the spine with off-centre impacts with the pool or sea bottom. Diving-related injuries range from 2.3 in a South African study to 21% of spinal cord injuries in Poland. Alcohol and diving do not mix because of diminished awareness and information processing. Children aged under 13 years suffer fewer cervical injuries (1 to 4%), but complication rates are relatively high for this group. Sports trauma (diving-related in particular) is one of the more prevalent causes of spinal cord injury in children aged 6 to 15 years. The highest incidence occurs among those aged 10 to 14, followed by the group aged 5 to 9 years. This contradicts the common perception that 15-to 19-year-olds comprise the highest risk group. Boys are more frequently injured, and swimming pools are more common as an injury location then is the case with adults. The role played by water depth has been conclusively ascertained; technique, and therefore education, appear to be more important considerations in injury prevention. Although 89% of injuries occur in water < 1.52m, injuries are rare in water of 0.46 to 0.61m. Care with pool design to avoid sudden depth changes and the resultant "spinal wall' is necessary. Minimum depth values for diving vary from 1 to 1.52 m. Velocities and angles of entry are considered to ascertain the body's decelerative capacity upon entry. The scoop, racing start dive has been shown to require at least 1.22 m of water even when practised by trained divers; the risks involved must therefore be weighed against the fact that it may be no faster than more conventional dives. While it may be safe to perform kneeling and crouching dives into shallowers water, standing dives by untrained divers require a greater margin of error. Lack of education is an issue which needs to be addressed and this paper makes recommendations for safety practices such as steering up to the surface, head protection with the arms and only diving when absolutely necessary.

Adult↗
PubMed2003

Diving experience and the aerobic dive capacity of muskrats: does training produce a better diver?

We tested the hypothesis that the body oxygen stores, aerobic dive limit (ADL) and dive performance of muskrats can be enhanced by dive-conditioning in a laboratory setting. We compared several key variables in 12 muskrats trained to swim a 16 m underwater course to a feeding station ('divers') with those of 12 animals precluded from diving but required to travel identical distances in water to feed ('surface swimmers'). Acclimated muskrats assigned to each group were trained concurrently over a 9-11 week period. We observed significant gains in the haematocrit (P=0.0005) and blood haemoglobin concentration (P=0.015) of 'divers', but not 'surface swimmers'. The post-training blood O(2) store calculated for 'divers' (22.9 ml O(2) kg(-1)) was nearly 26% higher than that (18.2 ml O(2) kg(-1)) derived for 'surface swimmers' (P=0.03). Dive-conditioning had no apparent effect on lung volume, whole blood and plasma volumes, nor on the glycogen level and buffering capacity of skeletal muscles. Cardiac and skeletal muscle myoglobin levels were also similar in both test groups following training. The mean total body oxygen store of 'divers' (37.8ml O(2) STPD kg(-1)) was 13.5% higher (P=0.037) than for 'surface swimmers' (33.3 ml O(2) STPD kg(-1)), an increase attributed entirely to the gain in blood O(2) storage capacity of the former group. However, owing to a slightly higher estimate of diving metabolic rate in dive-conditioned animals, the calculated ADL for this group (61.3 s) was indistinguishable from that of 'surface swimmers' (61.8 s). Few differences were observed in the post-training dive behaviour of 'surface swimmers' and 'divers', a finding consistent with the strong similarity in their calculated aerobic dive capacities.

Animals↗
PubMed2002

Body oxygen stores, aerobic dive limits and diving behaviour of the star-nosed mole (Condylura cristata) and comparisons with non-aquatic talpids.

The dive performance, oxygen storage capacity and partitioning of body oxygen reserves of one of the world's smallest mammalian divers, the star-nosed mole Condylura cristata, were investigated. On the basis of 722 voluntary dives recorded from 18 captive star-nosed moles, the mean dive duration (9.2+/-0.2 s; mean +/- S.E.M.) and maximum recorded dive time (47 s) of this insectivore were comparable with those of several substantially larger semi-aquatic endotherms. Total body O(2) stores of adult star-nosed moles (34.0 ml kg(-1)) were 16.4 % higher than for similarly sized, strictly fossorial coast moles Scapanus orarius (29.2 ml kg(-1)), with the greatest differences observed in lung and muscle O(2) storage capacity. The mean lung volume of C. cristata (8.09 ml 100 g(-1)) was 1.81 times the predicted allometric value and exceeded that of coast moles by 65.4 % (P=0.0001). The overall mean myoglobin (Mb) concentration of skeletal muscles of adult star-nosed moles (13.57+/-0.40 mg g(-1) wet tissue, N=7) was 19.5 % higher than for coast moles (11.36+/-0.34 mg g(-1) wet tissue, N=10; P=0.0008) and 54.2 % higher than for American shrew-moles Neurotrichus gibbsii (8.8 mg g(-1) wet tissue; N=2). The mean skeletal muscle Mb content of adult star-nosed moles was 91.1 % higher than for juveniles of this species (P<0.0001). On the basis of an average diving metabolic rate of 5.38+/-0.35 ml O(2) g(-1) h(-1) (N=11), the calculated aerobic dive limit (ADL) of star-nosed moles was 22.8 s for adults and 20.7 s for juveniles. Only 2.9 % of voluntary dives by adult and juvenile star-nosed moles exceeded their respective calculated ADLs, suggesting that star-nosed moles rarely exploit anaerobic metabolism while diving, a conclusion supported by the low buffering capacity of their skeletal muscles. We suggest that a high mass-specific O(2) storage capacity and relatively low metabolic cost of submergence are key contributors to the impressive dive performance of these diminutive insectivores.

Aerobiosis↗