scholarly journals The extra burden of motherhood: reduced dive duration associated with pregnancy status in a deep-diving mammal, the northern elephant seal

2018 ◽  
Vol 14 (2) ◽  
pp. 20170722 ◽  
Author(s):  
Luis A. Hückstädt ◽  
Rachel R. Holser ◽  
Michael S. Tift ◽  
Daniel P. Costa
Keyword(s):  
Marine Mammals ◽  
Elephant Seal ◽  
Dive Duration ◽  
Northern Elephant Seal ◽  
Continuous Increase ◽  
Elephant Seals ◽  
Deep Diving ◽  
Pregnancy Status ◽  
The Cost ◽  
Free Ranging

The cost of pregnancy is hard to study in marine mammals, particularly in species that undergo pregnancy while diving continuously at sea such as elephant seals (genus Mirounga ). We analysed the diving behaviour of confirmed pregnant and non-pregnant northern elephant seals ( M. angustirostris , n = 172) and showed that after an initial continuous increase in dive duration, dives of pregnant females become shorter after week 17. The reasons for this reduction in dive duration remain unknown, but we hypothesize that increased fetal demand for oxygen could be the cause. Our findings reveal an opportunity to explore the use of biologging data to investigate pregnancy status of free-ranging marine mammals and factors that could affect pregnancy success.

Blood viscosity and optimal hematocrit in a deep-diving mammal, the northern elephant seal (Mirounga angustirostris)

1986 ◽  
Vol 64 (10) ◽  
pp. 2081-2085 ◽  
Author(s):  
Michael S. Hedrick ◽  
Deborah A. Duffield ◽  
Lanny H. Cornell
Keyword(s):  
Oxygen Transport ◽  
Blood Viscosity ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Elephant Seal ◽  
Oxygen Storage ◽  
Diving Behavior ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Deep Diving

Elephant seals offer a unique opportunity to examine rheological characteristics of blood because of the normally high hematocrits in this species. A comparison of blood viscosity of the elephant seal with that of a terrestrial mammal (rabbit; HCT = 35%) reveals a threefold increase in viscosity of elephant seal blood over that of rabbit blood due to the high hematocrit (HCT = 65%). While the increased hematocrit of elephant seal blood reflects increased oxygen storage capacity, blood oxygen transport may actually be reduced by the effects of increased blood viscosity on blood flow. Elephant seal plasma viscosity was also higher than that of rabbit plasma; this was associated with a higher concentration of plasma proteins. There were no apparent differences in the viscous properties of the red blood cells of the two species. The theoretically optimal hematocrit was determined in vitro for reconstituted blood from each species and compared with the observed in vivo hematocrit. It was found that the observed hematocrit of the elephant seal lies far to the right of the predicted hematocrit for optimal oxygen transport, while the rabbit hematocrit was identical with the predicted value. These results suggest that elephant seals have increased oxygen storage capacity at the expense of optimizing oxygen transport. The observed increase in hematocrit and viscosity may be of importance in considering the diving behavior and energetics of elephant seals.

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.

scholarly journals In-air hearing in Hawaiian monk seals: implications for understanding the auditory biology of Monachinae seals

2021 ◽  
Author(s):  
Brandi Ruscher ◽  
Jillian M. Sills ◽  
Beau P. Richter ◽  
Colleen Reichmuth
Keyword(s):  
Marine Mammals ◽  
Elephant Seal ◽  
Critical Ratio ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Hearing Ability ◽  
Highly Sensitive ◽  
Monk Seals ◽  
Management And Conservation ◽  
Hearing Abilities

AbstractThe auditory biology of Monachinae seals is poorly understood. Limited audiometric data and certain anatomical features suggest that these seals may have reduced sensitivity to airborne sounds compared to related species. Here, we describe the in-air hearing abilities of a Hawaiian monk seal (Neomonachus schauinslandi) trained to participate in a psychophysical paradigm. We report absolute (unmasked) thresholds for narrowband signals measured in quiet conditions across the range of hearing and masked thresholds measured in the presence of octave-band noise at two frequencies. The behavioral audiogram indicates a functional hearing range from 0.1 to 33 kHz and poor sensitivity, with detection thresholds above 40 dB re 20 µPa. Critical ratio measurements are elevated compared to those of other seals. The apparently reduced terrestrial hearing ability of this individual—considered with available auditory data for a northern elephant seal (Mirounga angustirostris)—suggests that hearing in Monachinae seals differs from that of the highly sensitive Phocinae seals. Exploration of phylogenetic relationships and anatomical traits support this claim. This work advances understanding of the evolution of hearing in amphibious marine mammals and provides updated information that can be used for management and conservation of endangered Hawaiian monk seals.

Relationships between plasma ketones and fasting duration in neonatal elephant seals

1990 ◽  
Vol 259 (5) ◽  
pp. R1086-R1089 ◽  
Author(s):  
M. A. Castellini ◽  
D. P. Costa
Keyword(s):  
Ketone Bodies ◽  
Elephant Seal ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Long Duration ◽  
Fat Stores ◽  
Low Levels ◽  
Beta Hydroxybutyrate ◽  
Fasting Duration ◽  
Circulating Levels

Long-duration fasting in mammals can ultimately lead to stage three terminal starvation, which is characterized by depleted fat stores, a metabolic shift away from fat metabolism toward lean tissue catabolism, and a sharp decline in circulating levels of plasma fatty acids and ketone bodies. However, this biochemical shift has never been observed outside of the laboratory in a naturally fasting, nonhibernating mammal. In the current study, plasma levels of the ketone body D-beta-hydroxybutyrate (beta-HBA) were assayed in 10 Northern elephant seal pups during suckling and the postweaning fast and in 12 fasting adult seals. Plasma beta-HBA concentration in the pups was minimal during suckling (0.09 +/- 0.06 mM; n = 10) and began to increase immediately after weaning. The concentration rose until about 55 days into the fast (1.34 +/- 0.36 mM; n = 10) and then declined sharply. Within 10 days of this deflection point, the seal pups left for sea. By contrast, adult elephant seals showed consistently low levels of beta-HBA after several months of fasting (0.06 +/- 0.07 mM; n = 12). The data suggest that the duration of fasting in elephant seal pups may be determined, in part, by biochemical shifts that occur near the end of the fast and that the regulation of ketone concentration is different in fasting neonatal and adult elephant seals.

Aggression in the Female Northern Elephant Seal, Mirounga Angustirostris

Behaviour ◽  
1978 ◽  
Vol 64 (1-2) ◽  
pp. 158-171 ◽  
Author(s):  
T.E. Christenson ◽  
B.J. Le Boeuf
Keyword(s):  
Reproductive Success ◽  
Aggressive Behavior ◽  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Advantages And Disadvantages ◽  
Northern Elephant Seals ◽  
Pup Survival ◽  
Male Activity

AbstractMaternal aggressive behavior of northern elephant seals enhances reproductive success by increasing the likelihood of pup survival. Detailed observations of marked mother-pup pairs revealed that female aggressiveness increased dramatically after giving birth. Maternal aggressiveness also correlated negatively with the number of times the pup was bitten by alien females. Mothers of these pups were less aggressive than the 17 whose pups survived. Pup behavior was not directly related to mortality. Frequencies of interfemale aggressive encounters were compared for different beach areas. Aggression was most frequent on the smallest area, where interfemale distance was the shortest, and tidal action extreme. Aggression was least frequent on the sparcely populated beach, affected little by tide or male activity. Interfemale distance was greatest here. Reproductive advantages and disadvantages of pupping on each area are noted.

Diving behavior in relation to ambient water temperature in northern elephant seals

1994 ◽  
Vol 72 (4) ◽  
pp. 643-651 ◽  
Author(s):  
Hiroshi Hakoyama ◽  
Burney J. Le Boeuf ◽  
Yasuhiko Naito ◽  
Wataru Sakamoto
Keyword(s):  
Water Temperature ◽  
Elephant Seal ◽  
Diving Behavior ◽  
Mirounga Angustirostris ◽  
Ambient Water ◽  
Northern Elephant Seal ◽  
Elephant Seals ◽  
Northern Elephant Seals ◽  
Abrupt Changes ◽  
Ambient Water Temperature

Our aim was to describe changes in ambient water temperature during the course of migration by northern elephant seals (Mirounga angustirostris) and to examine evidence for the seal using abrupt temperature gradients for locating prey. During migration in the post breeding season, the diving patterns of 10 adult females and 7 breeding-age males from Año Nuevo, California, were recorded with time–depth recorders in 1989–1991. Recorded sea surface temperatures declined from 11–13 °C to a low of 3–9 °C as the seals moved north and increased as they returned. Depth of diving was not closely linked to sharp thermal gradients. A thermocline was evident only at the beginning and end of the migration in less than 100 m of water, where less than 2% of diving takes place. There were sex differences in the temperature range at the depths where 75% of diving and foraging occurred, owing in part to habitat separation. The temperatures were lower and the range narrower for females (4.2–5.2 °C at 388–622 m) than for males (5.3–6.0 °C at 179–439 m). We conclude that the northern elephant seal habitat does not provide abrupt changes in temperature that might serve as important cues for locating prey.

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.

scholarly journals Muscle transcriptome response to ACTH administration in a free-ranging marine mammal

2015 ◽  
Vol 47 (8) ◽  
pp. 318-330 ◽  
Author(s):  
Jane I. Khudyakov ◽  
Cory D. Champagne ◽  
Likit Preeyanon ◽  
Rudy M. Ortiz ◽  
Daniel E. Crocker
Keyword(s):  
Stress Responses ◽  
Marine Mammal ◽  
Target Genes ◽  
Elephant Seal ◽  
Laboratory Animals ◽  
Stress Axis ◽  
Northern Elephant Seal ◽  
Free Living ◽  
Corticosteroid Hormones ◽  
Free Ranging

While much of our understanding of stress physiology is derived from biomedical studies, little is known about the downstream molecular consequences of adaptive stress responses in free-living animals. We examined molecular effectors of the stress hormones cortisol and aldosterone in the northern elephant seal, a free-ranging study system in which extreme physiological challenges and cortisol fluctuations are a routine part of life history. We stimulated the neuroendocrine stress axis by administering exogenous adrenocorticotropic hormone (ACTH) and examined the resultant effects by measuring corticosteroid hormones, metabolites, and gene expression before, during, and following administration. ACTH induced an elevation in cortisol, aldosterone, glucose, and fatty acids within 2 h, with complete recovery observed within 24 h of administration. The global transcriptional response of elephant seal muscle tissue to ACTH was evaluated by transcriptomics and involved upregulation of a highly coordinated network of conserved glucocorticoid (GC) target genes predicted to promote metabolic substrate availability without causing deleterious effects seen in laboratory animals. Transcriptional recovery from ACTH was characterized by downregulation of GC target genes and restoration of cell proliferation, metabolism, and tissue maintenance pathways within 24 h. Differentially expressed genes included several adipokines not previously described in muscle, reflecting unique metabolic physiology in fasting-adapted animals. This study represents one of the first transcriptome analyses of cellular responses to hypothalamic-pituitary-adrenal axis stimulation in a free-living marine mammal and suggests that compensatory, tissue-sparing mechanisms may enable marine mammals to maintain cortisol and aldosterone sensitivity while avoiding deleterious long-term consequences of stress.

scholarly journals Blood Oxygen Depletion Is Independent of Dive Function in a Deep Diving Vertebrate, the Northern Elephant Seal

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e83248 ◽  
Author(s):  
Jessica U. Meir ◽  
Patrick W. Robinson ◽  
L. Ignacio Vilchis ◽  
Gerald L. Kooyman ◽  
Daniel P. Costa ◽  
...  
Keyword(s):  
Oxygen Depletion ◽  
Elephant Seal ◽  
Blood Oxygen ◽  
Northern Elephant Seal ◽  
Deep Diving

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.

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