scholarly journals Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal

2018 ◽  
Vol 285 (1872) ◽  
pp. 20172782 ◽  
Author(s):  
Sarah H. Peterson ◽  
Joshua T. Ackerman ◽  
Daniel E. Crocker ◽  
Daniel P. Costa
Keyword(s):  
Life History ◽  
Mercury Contamination ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Northern Elephant Seals ◽  
Large Fluctuations ◽  
Before And After ◽  
Blood Mercury ◽  
Annual Life History ◽  
Free Ranging

Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals ( Mirounga angustirostris ) before and after lengthy at sea foraging trips ( n = 89) or fasting periods on land ( n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas the highest muscle mercury concentrations were observed when seals returned to land to moult. Mean female blood mercury concentrations decreased by 30% across each of the two annual foraging trips, demonstrating a foraging-associated dilution of mercury concentrations as seals gained mass. Blood mercury concentrations increased by 103% and 24% across the breeding and moulting fasts, respectively, demonstrating a fasting-associated concentration of mercury as seals lost mass. In contrast to blood, mercury concentrations in female's muscle increased by 19% during the post-breeding foraging trip and did not change during the post-moulting foraging trip. While fasting, female muscle mercury concentrations increased 26% during breeding, but decreased 14% during moulting. Consequently, regardless of exposure, an animal's contaminant concentration can be markedly influenced by their annual life-history events.

Drift diving in female northern elephant seals: implications for food processing

1997 ◽  
Vol 75 (1) ◽  
pp. 27-39 ◽  
Author(s):  
Daniel E. Crocker ◽  
Burney J. Le Boeuf ◽  
Daniel P. Costa
Keyword(s):  
Body Fat ◽  
Average Rate ◽  
Metabolic Cost ◽  
Late Gestation ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Northern Elephant Seals ◽  
Before And After ◽  
Free Ranging ◽  
Active Swimming

We tested predictions from the hypothesis that northern elephant seals, Mirounga angustirostris, drift during the bottom segment of some dives (called C dives) using oxygen saved from reduced locomotion to process food. Sixteen free-ranging dive records were obtained with microcomputer dive recorders attached to 13 adult females from Año Nuevo, California, during biannual foraging trips when they were in early or late stages of gestation; swim speed was recorded throughout one dive record. Body composition was measured before and after trips to sea. C dives with a bout length of 2 – 10 dives and a mean duration similar to those of other dive types made up 6.3 ± 1.9% of the dives recorded. Swim speed was near or below the recorder stall speed (0.22 m/s) during the second, drift segment of these dives. The rate of vertical depth change while drifting varied little within bouts, was initially significantly correlated with the ratio of fat to lean body mass at departure, and changed systematically as the seals fed while at sea. Females in early gestation, with initial mean body fat of 24%, drifted down at a mean rate of 0.31 ± 0.04 m/s; females in late gestation, with mean body fat approaching 36%, drifted up at an average rate of 0.17 ± 0.05 m/s. The frequency, duration, and temporal pattern of drift dives were correlated with foraging behavior, supporting the hypothesis that drifting while diving is associated with the metabolic cost of processing food. This study provides indirect support for the hypothesis that elephant seals suspend active swimming on certain dives, during which a greater proportion of oxygen stores is allocated to the processing of food, without interrupting the seals' normal pattern of continuous diving and allowing them to remain within their aerobic dive limit.

Lifetime reproductive success of northern elephant seals (Mirounga angustirostris)

2019 ◽  
Vol 97 (12) ◽  
pp. 1203-1217 ◽  
Author(s):  
Burney Le Boeuf ◽  
Richard Condit ◽  
Joanne Reiter
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Natural Population ◽  
Lifetime Reproductive Success ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Young Females ◽  
Darwinian Fitness ◽  
Northern Elephant Seals ◽  
Selection For

Lifetime reproductive success of individuals in a natural population provides an estimate of Darwinian fitness. We calculated lifetime reproductive success in a colony of female northern elephant seals (Mirounga angustirostris (Gill, 1866)) by monitoring annual breeding throughout life of 7735 female weanlings marked individually at Año Nuevo, California, USA, from 1963 to 2005. Great variation in lifetime reproductive success was evident in three aspects of life history: (1) 75% of the females died before reaching breeding age and produced no pups; (2) nearly half of the survivors bred for only a few years before dying, and young females had low weaning success; (3) less than 1% of the females in the sample were exceptionally successful producing up to 20 pups in life. Many females that bred early, while still growing, had decreased lifespan, low weaning success, and lower lifetime reproductive success than females that postponed first breeding. Exceptional reproductive success was associated with giving birth annually, living long (up to age 23), and weaning large pups that were more likely to survive and breed. We conclude that there is strong selection for increased lifespan and multiparous supermoms that contribute significantly to pup production in the next generation.

scholarly journals Respiration and heart rate at the surface between dives in northern elephant seals

2000 ◽  
Vol 203 (21) ◽  
pp. 3265-3274 ◽  
Author(s):  
B.J. Le Boeuf ◽  
D.E. Crocker ◽  
J. Grayson ◽  
J. Gedamke ◽  
P.M. Webb ◽  
...  
Keyword(s):  
Heart Rate ◽  
Mirounga Angustirostris ◽  
Digital Audio ◽  
Adult Males ◽  
Elephant Seals ◽  
Diving Depth ◽  
Surface Time ◽  
Northern Elephant Seals ◽  
Audio Tape Recorder ◽  
Free Ranging

All underwater activities of diving mammals are constrained by the need for surface gas exchange. Our aim was to measure respiratory rate (fb) and heart rate (fh) at the surface between dives in free-ranging northern elephant seals Mirounga angustirostris. We recorded fb and fh acoustically in six translocated juveniles, 1.8-2. 4 years old, and three migrating adult males from the rookery at Ano Nuevo, California, USA. To each seal, we attached a diving instrument to record the diving pattern, a satellite tag to track movements and location, a digital audio tape recorder or acoustic datalogger with an external hydrophone to record the sounds of respiration and fh at the surface, and a VHF transmitter to facilitate recovery. During surface intervals averaging 2.2+/−0.4 min, adult males breathed a mean of 32.7+/−5.4 times at a rate of 15. 3+/−1.8 breaths min(−)(1) (means +/− s.d., N=57). Mean fh at the surface was 84+/−3 beats min(−)(1). The fb of juveniles was 26 % faster than that of adult males, averaging 19.2+/−2.2 breaths min(−)(1) for a mean total of 41.2+/−5.0 breaths during surface intervals lasting 2.6+/−0.31 min. Mean fh at the surface was 106+/−3 beats min(−)(1). fb and fh did not change significantly over the course of surface intervals. Surface fb and fh were not clearly associated with levels of exertion, such as rapid horizontal transit or apparent foraging, or with measures of immediately previous or subsequent diving performance, such as diving duration, diving depth or swimming speed. Together, surface respiration rate and the duration of the preceding dive were significant predictors of surface interval duration. This implies that elephant seals minimize surface time spent loading oxygen depending on rates of oxygen uptake and previous depletion of stores.

Use of 15N-enriched glycine to estimate vibrissa growth in free-ranging northern elephant seals Mirounga angustirostris

2019 ◽  
Vol 614 ◽  
pp. 199-207 ◽  
Author(s):  
D Aurioles-Gamboa ◽  
SD Newsome ◽  
JL Hassrick ◽  
T Acosta-Pachón ◽  
F Aurioles-Rodríguez ◽  
...  
Keyword(s):  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Northern Elephant Seals ◽  
Free Ranging

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 The rise and fall of dialects in northern elephant seals

2018 ◽  
Vol 285 (1892) ◽  
pp. 20182176 ◽  
Author(s):  
Caroline Casey ◽  
Colleen Reichmuth ◽  
Daniel P. Costa ◽  
Burney Le Boeuf
Keyword(s):  
Mammalian Species ◽  
Structural Complexity ◽  
Mirounga Angustirostris ◽  
Geographical Differences ◽  
Migration Patterns ◽  
Elephant Seals ◽  
The North ◽  
Vocal Behaviour ◽  
Northern Elephant Seals ◽  
The North Pacific

Vocal dialects are fundamental to our understanding of the transmission of social behaviours between individuals and populations, however few accounts trace this phenomenon among mammals over time. Northern elephant seals ( Mirounga angustirostris ) provide a rare opportunity to examine the trajectory of dialects in a long-lived mammalian species. Dialects were first documented in the temporal patterns of the stereotyped vocal displays produced by breeding males at four sites in the North Pacific in 1968 and 1969, as the population recovered from extreme exploitation. We evaluated the longevity of these geographical differences by comparing these early recordings to calls recently recorded at these same locations. While the presence of vocal dialects in the original recordings was re-confirmed, geographical differences in vocal behaviour were not found at these breeding rookeries nearly 50 years later. Moreover, the calls of contemporary males displayed more structural complexity after approximately four generations, with substantial between-individual variation and call features not present in the historical data. In the absence of measurable genetic variation in this species—owing to an extreme population bottleneck—a combination of migration patterns and cultural mutation are proposed as factors influencing the fall of dialects and the dramatic increase in call diversity.

The effect of rehabilitation of northern elephant seals (Mirounga angustirostris) on antimicrobial resistance of commensal Escherichia coli

2009 ◽  
Vol 133 (3) ◽  
pp. 264-271 ◽  
Author(s):  
Robyn A. Stoddard ◽  
E. Rob Atwill ◽  
Patricia A. Conrad ◽  
Barbara A. Byrne ◽  
Spencer Jang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Mirounga Angustirostris ◽  
Elephant Seals ◽  
Northern Elephant Seals
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