Heart rates of northern elephant seals diving at sea and resting on the beach.

1997 ◽  
Vol 200 (15) ◽  
pp. 2083-2095 ◽  
Author(s):  
R D Andrews ◽  
D R Jones ◽  
J D Williams ◽  
P H Thorson ◽  
G W Oliver ◽  
...  
Keyword(s):  
Heart Rate ◽  
Dive Depth ◽  
Dive Duration ◽  
Cardiac Response ◽  
Elephant Seals ◽  
Heart Rates ◽  
Data Loggers ◽  
Long Duration ◽  
Northern Elephant Seals ◽  
Instantaneous Heart Rate

Heart rates of northern elephant seals diving at sea and during apnoea on land were monitored to test whether a cardiac response to submergence is an important factor in their ability to make repetitive, long-duration dives. Seven juvenile northern elephant seals were captured at Año Nuevo, CA, instrumented and translocated to release sites around Monterey Bay. Heart rate and dive depth were recorded using custom-designed data loggers and analogue tape monitors during the seals' return to Año Nuevo. Heart rates during apnoea and eupnoea were recorded from four of the seals after they hauled out on the beach. Diving patterns were very similar to those of naturally migrating juveniles. The heart rate response to apnoea at sea and on land was a prompt bradycardia, but only at sea was there an anticipatory tachycardia before breathing commenced. Heart rate at sea declined by 64% from the surface rate of 107 +/- 3 beats min-1 (mean +/- S.D.), while heart rate on land declined by 31% from the eupnoeic rate of 65 +/- 8 beats min-1. Diving heart rate was inversely related to dive duration in a non-linear fashion best described by a continuous, curvilinear model, while heart rate during apnoea on land was independent of the duration of apnoea. Occasionally, instantaneous heart rate fell as low as 3 beats min-1 during diving. Although bradycardia occurs in response to apnoea both at sea and on land, only at sea is heart rate apparently regulated to minimise eupnoeic time and to ration oxygen stores to ensure adequate supplies for the heart and brain not only as the dive progresses normally but also when a dive is abnormally extended.

scholarly journals Heart rates and abdominal temperatures of free-ranging South Georgian shags, Phalacrocorax georgianus

1997 ◽  
Vol 200 (4) ◽  
pp. 661-675 ◽  
Author(s):  
R M Bevan ◽  
I L Boyd ◽  
P J Butler ◽  
K Reid ◽  
A J Woakes ◽  
...  
Keyword(s):  
Heart Rate ◽  
Dive Depth ◽  
Dive Duration ◽  
Diving Behaviour ◽  
The South ◽  
Data Logger ◽  
Heart Rates ◽  
The Mean ◽  
Free Ranging ◽  
Mean Heart Rate

The South Georgian shag (Phalacrocorax georgianus) shows a remarkable diving ability comparable to that of penguins, yet nothing is known of the physiology of these birds. In this study, heart rates and abdominal temperatures were recorded continuously in four free-ranging South Georgian shags using an implanted data-logger. A time­depth recorder was also attached to the back of the implanted birds to record their diving behaviour. The diving behaviour of the birds was essentially similar to that reported in other studies, with maximum dive durations for individual birds ranging between 140 and 287 s, and maximum depths between 35 and 101 m. The birds, while at the nest, had a heart rate of 104.0±13.1 beats min-1 (mean ± s.e.m.) and an abdominal temperature of 39.1±0.2 °C. During flights of 221±29 s, heart rate and abdominal temperature rose to 309.5±18.0 beats min-1 and 40.1±0.3 °C, respectively. The mean heart rate during diving, at 103.7±13.7 beats min-1, was not significantly different from the resting values, but the minimum heart rate during a dive was significantly lower at 64.8±5.8 beats min-1. The minimum heart rate during a dive was negatively correlated with both dive duration and dive depth. Abdominal temperature fell progressively during a diving bout, with a mean temperature at the end of a bout of 35.1±1.7 °C. The minimum heart rate during diving is at a sub-resting level, which suggests that the South Georgian shag responds to submersion with the 'classic' dive response of bradycardia and the associated peripheral vasoconstriction and utilisation of anaerobic metabolism. However, the reduction in abdominal temperature may reflect a reduction in the overall metabolic rate of the animal such that the bird can remain aerobic while submerged.

Prolonged, continuous, deep diving by northern elephant seals

1989 ◽  
Vol 67 (10) ◽  
pp. 2514-2519 ◽  
Author(s):  
Burney J. Le Boeuf ◽  
Yasuhiko Naito ◽  
Anthony C. Huntley ◽  
Tomohiro Asaga
Keyword(s):  
Dive Depth ◽  
Dive Duration ◽  
Mirounga Angustirostris ◽  
Steady State Condition ◽  
Elephant Seals ◽  
Deep Diving ◽  
Physiological Processes ◽  
Northern Elephant Seals ◽  
Extended Surface ◽  
The Mean

An earlier study showed that female northern elephant seals (Mirounga angustirostris) dive deeply and continuously during the first 1–3 weeks at sea following lactation. We report that this dive pattern is maintained for the entire 2½-month period at sea. Time–depth recorders were attached to six adult females at Año Nuevo, California; three instruments recorded continuously and three instruments recorded every 3rd day at sea. The mean dive rate was 2.5–3.3 dives per hour, with a mean of < 3.5 min on the surface between dives. This resulted in females spending 83–90% of the time at sea underwater. Interruption of continuous diving, characterized by extended surface intervals with a mean of 51.9 ± 65.5 min, was rare, following only 0.42% of the dives. Modal dive duration per female was in the range 17.1–22.5 min. The longest dive was 62 min and was followed by a surface interval of < 2.6 min. Modal dive depth per female was in the range 500–700 m; three females had dives that exceeded 1000 m, with the deepest dive estimated at 1250 m. Deep diving to 500 m or more was always preceded by a descending-staircase pattern of initially shallow to increasingly deeper dives. The continuous, deep diving pattern of this pelagic seal is evidently a steady-state condition. This has important implications for understanding diving adaptations and the physiological processes underlying them.

Heart rates and diving behavior of leatherback sea turtles in the eastern pacific ocean

1999 ◽  
Vol 202 (9) ◽  
pp. 1115-1125 ◽  
Author(s):  
A.L. Southwood ◽  
R.D. Andrews ◽  
M.E. Lutcavage ◽  
F.V. Paladino ◽  
N.H. West ◽  
...  
Keyword(s):  
Heart Rate ◽  
Sea Turtles ◽  
Dive Depth ◽  
Dive Duration ◽  
Diving Behavior ◽  
Leatherback Turtles ◽  
Heart Rates ◽  
The Mean ◽  
Leatherback Sea Turtles ◽  
Mean Heart Rate

Heart rates and diving behavior of leatherback sea turtles (Dermochelys coriacea) were monitored at sea during the internesting interval. Instruments that recorded the electrocardiogram and the depth and duration of dives were deployed on six female leatherback turtles as they laid eggs at Playa Grande, Costa Rica. Turtles dived continually for the majority of the internesting interval and spent 57–68 % of the time at sea submerged. Mean dive depth was 19+/−1 m (mean +/− s.d.) and the mean dive duration was 7.4+/−0.6 min. Heart rate declined immediately upon submergence and continued to fall during descent. All turtles showed an increase in heart rate before surfacing. The mean heart rate during dives of 17.4+/−0.9 beats min-1 (mean +/− s.d.) was significantly lower than the mean heart rate at the surface of 24.9+/−1.3 beats min-1 (P&lt;0.05). Instantaneous heart rates as low as 1.05 beats min-1 were recorded during a 34 min dive. The mean heart rate over the entire dive cycle (dive + succeeding surface interval; 19.4+/−1.3 beats min-1) was more similar to the heart rate during diving than to the heart rate at the surface. Although dive and surface heart rates were significantly different from each other, heart rates during diving were 70 % of heart rates at the surface, showing that leatherback turtles do not experience a dramatic bradycardia during routine diving.

Diurnal and seasonal variations in the duration and depth of the longest dives in southern elephant seals (Mirounga leonina): possible physiological and behavioural constraints

2001 ◽  
Vol 204 (4) ◽  
pp. 649-662 ◽  
Author(s):  
K.A. Bennett ◽  
B.J. McConnell ◽  
M.A. Fedak
Keyword(s):  
Dive Depth ◽  
Dive Duration ◽  
Time Of Day ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Dive Behaviour ◽  
Physiological Capacity ◽  
Data Loggers ◽  
Southern Elephant Seals ◽  
Seasonal Basis

This study seeks to understand how the physiological constraints of diving may change on a daily and seasonal basis. Dive data were obtained from southern elephant seals (Mirounga leonina) from South Georgia using satellite relay data loggers. We analysed the longest (95th percentile) dive durations as proxies for physiological dive limits. A strong, significant relationship existed between the duration of these dives and the time of day and week of year in which they were performed. The depth of the deepest dives also showed a significant, but far less consistent, relationship with local time of day and season. Changes in the duration of the longest dives occurred irrespective of their depth. Dives were longest in the morning (04:00-12:00 h) and shortest in the evening (16:00-00:00 h). The size of the fluctuation varied among animals from 4.0 to 20.0 min. The daily pattern in dive depth was phase-shifted in relation to the diurnal rhythm in dive duration. Dives were deeper at midday and shallower around midnight. Greater daily changes in duration occurred in seals feeding in the open ocean than in those foraging on the continental shelf. The seasonal peak in the duration of the longest dives coincided with austral midwinter. The size of the increase in dive duration from autumn/spring to winter ranged from 11.5 to 30.0 min. Changes in depth of the longest dives were not consistently associated with particular times of year. The substantial diurnal and seasonal fluctuations in maximum dive duration may be a result of changes in the physiological capacity to remain submerged, in addition to temporal changes in the ecological constraints on dive behaviour. We speculate about the role of melatonin as a hormonal mediator of diving capability.

Continuous, deep diving in female northern elephant seals, Mirounga angustirostris

1988 ◽  
Vol 66 (2) ◽  
pp. 446-458 ◽  
Author(s):  
Burney J. Le Boeuf ◽  
Daniel P. Costa ◽  
Anthony C. Huntley ◽  
Steven D. Feldkamp
Keyword(s):  
Mass Gain ◽  
Dive Depth ◽  
Dive Duration ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Deep Diving ◽  
Northern Elephant Seals ◽  
The Mean ◽  
Free Ranging ◽  
Nearly Continuous

The free-ranging dive pattern of seven adult female northern elephant seals (Mirounga angustirostris) was obtained with time–depth recorders during the first 14 – 27 days at sea following lactation. The instruments were recovered and mass gain at sea determined when the animals returned to the rookery at Año Nuevo, California, to molt. The seals gained a mean of 76.5 ± 13.9 kg during a mean of 72.6 ± 5.0 days at sea. The mean dive rate was 2.7 ± 0.2 dives/h and diving was virtually continuous during the entire period at sea. Mean dive duration was 19.2 ± 4.3 min with the longest submersion lasting 48 min. Mean surface interval between dives was 2.8 ± 0.5 min, so that only 14.4% of the recorded time at sea was spent on the surface. Surface intervals did not vary with the duration of preceding or succeeding dives. Modal dive depth for each female was between 350 and 650 m. The maximum dive depth was estimated at 894 m, a depth record for pinnipeds. The deep, nearly continuous dive pattern of female northern elephant seals differs from the dive pattern of other pinnipeds and appears to serve in foraging, energy conservation, and predator avoidance.

Heart Rate and Oxygen Consumption of Northern Elephant Seals during Diving in the Laboratory

1998 ◽  
Vol 71 (1) ◽  
pp. 116-125 ◽  
Author(s):  
Paul M. Webb ◽  
Russel D. Andrews ◽  
Daniel P. Costa ◽  
Burney J. Le Boeuf
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Elephant Seals ◽  
Northern Elephant Seals

scholarly journals Locomotion in diving elephant seals: physical and physiological constraints

2007 ◽  
Vol 362 (1487) ◽  
pp. 2141-2150 ◽  
Author(s):  
Randall W Davis ◽  
Daniel Weihs
Keyword(s):  
Energy Savings ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Dive Depth ◽  
Elephant Seal ◽  
Dive Duration ◽  
Energetic Cost ◽  
Horizontal Distance ◽  
Flat Bottom ◽  
Elephant Seals

To better understand how elephant seals ( Mirounga angustirostris ) use negative buoyancy to reduce energy metabolism and prolong dive duration, we modelled the energetic cost of transit and deep foraging dives in an elephant seal. A numerical integration technique was used to model the effects of swim speed, descent and ascent angles, and modes of locomotion (i.e. stroking and gliding) on diving metabolic rate, aerobic dive limit, vertical displacement (maximum dive depth) and horizontal displacement (maximum horizontal distance along a straight line between the beginning and end locations of the dive) for aerobic transit and foraging dives. Realistic values of the various parameters were taken from previous experimental data. Our results indicate that there is little energetic advantage to transit dives with gliding descent compared with horizontal swimming beneath the surface. Other factors such as feeding and predator avoidance may favour diving to depth during migration. Gliding descent showed variable energy savings for foraging dives. Deep mid-water foraging dives showed the greatest energy savings (approx. 18%) as a result of gliding during descent. In contrast, flat-bottom foraging dives with horizontal swimming at a depth of 400 m showed less of an energetic advantage with gliding descent, primarily because more of the dive involved stroking. Additional data are needed before the advantages of gliding descent can be fully understood for male and female elephant seals of different age and body composition. This type of data will require animal-borne instruments that can record the behaviour, three-dimensional movements and locomotory performance of free-ranging animals at depth.

Correlation of depth and heart rate in harbour seal pups

2004 ◽  
Vol 82 (7) ◽  
pp. 1147-1156 ◽  
Author(s):  
J L Hicks ◽  
R J O'Hara Hines ◽  
J F Schreer ◽  
M O Hammill
Keyword(s):  
Heart Rate ◽  
River Estuary ◽  
Dive Depth ◽  
Dive Duration ◽  
Harbour Seal ◽  
Cardiac Responses ◽  
Cardiac Control ◽  
Apparent Relationship ◽  
St Lawrence River ◽  
Mean Heart Rate

Harbour seal (Phoca vitulina L., 1758) pups are aquatically active from birth and have been shown to develop increased cardiac control throughout the nursing period. In an attempt to quantify and compare these developmental changes, data previously collected on pups in the St. Lawrence River estuary, Quebec, Canada, were analyzed. Time–depth recorders and heart-rate recorders were employed on eight pups to obtain depth and heart-rate measurements simultaneously. Analyses involved partitioning the data into intervals of surface–dive–surface. These intervals were then allocated into nine consecutive segments: presurface, predive surface, descent, prebottom, bottom, postbottom, ascent, postdive surface, and postsurface. Mean heart rate for each segment was then correlated with the mean depth per segment and overall dive duration. With increasing dive depth, a decrease in heart-rate variability with age was observed. There was no apparent relationship between mean heart rate during the dive and overall dive duration. The proportion of time spent in the lower heart-rate mode was observed to increase with age during most phases of a dive. Relative changes in mean heart rate between consecutive dive segments indicated an initial decrease in mean heart rate prior to submersion and an increasing trend before surfacing. These findings indicate that harbour seal pups develop increased cardiac control prior to weaning and that anticipatory cardiac responses to diving and surfacing (bradycardia and tachycardia, respectively) may be evident.

scholarly journals Condition and mass impact oxygen stores and dive duration in adult female northern elephant seals

2010 ◽  
Vol 213 (4) ◽  
pp. 585-592 ◽  
Author(s):  
J. L. Hassrick ◽  
D. E. Crocker ◽  
N. M. Teutschel ◽  
B. I. McDonald ◽  
P. W. Robinson ◽  
...  
Keyword(s):  
Adult Female ◽  
Dive Duration ◽  
Elephant Seals ◽  
Northern Elephant Seals ◽  
Oxygen Stores

Extreme hypoxemic tolerance and blood oxygen depletion in diving elephant seals

2009 ◽  
Vol 297 (4) ◽  
pp. R927-R939 ◽  
Author(s):  
Jessica U. Meir ◽  
Cory D. Champagne ◽  
Daniel P. Costa ◽  
Cassondra L. Williams ◽  
Paul J. Ponganis
Keyword(s):  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Oxygen Depletion ◽  
Dive Duration ◽  
Aerobic Metabolism ◽  
Mirounga Angustirostris ◽  
Dissociation Curve ◽  
Elephant Seals ◽  
Store Depletion ◽  
Northern Elephant Seals

Species that maintain aerobic metabolism when the oxygen (O2) supply is limited represent ideal models to examine the mechanisms underlying tolerance to hypoxia. The repetitive, long dives of northern elephant seals ( Mirounga angustirostris) have remained a physiological enigma as O2 stores appear inadequate to maintain aerobic metabolism. We evaluated hypoxemic tolerance and blood O2 depletion by 1) measuring arterial and venous O2 partial pressure (Po2) during dives with a Po2/temperature recorder on elephant seals, 2) characterizing the O2-hemoglobin (O2-Hb) dissociation curve of this species, 3) applying the dissociation curve to Po2 profiles to obtain %Hb saturation (So2), and 4) calculating blood O2 store depletion during diving. Optimization of O2 stores was achieved by high venous O2 loading and almost complete depletion of blood O2 stores during dives, with net O2 content depletion values up to 91% (arterial) and 100% (venous). In routine dives (>10 min) PvO2 and PaO2 values reached 2–10 and 12–23 mmHg, respectively. This corresponds to So2 of 1–26% and O2 contents of 0.3 (venous) and 2.7 ml O2/dl blood (arterial), demonstrating remarkable hypoxemic tolerance as PaO2 is nearly equivalent to the arterial hypoxemic threshold of seals. The contribution of the blood O2 store alone to metabolic rate was nearly equivalent to resting metabolic rate, and mean temperature remained near 37°C. These data suggest that elephant seals routinely tolerate extreme hypoxemia during dives to completely utilize the blood O2 store and maximize aerobic dive duration.

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