The development of diving behavior in juvenile Weddell seals: pushing physiological limits in order to survive

1999 ◽  
Vol 77 (5) ◽  
pp. 737-747 ◽  
Author(s):  
Jennifer M Burns
Keyword(s):  
Blood Chemistry ◽  
Weddell Seal ◽  
Dive Duration ◽  
Foraging Strategies ◽  
Foraging Efficiency ◽  
Diving Behavior ◽  
Weddell Seals ◽  
Physiological Limits ◽  
Behavioral Constraints ◽  
Absolute Energy

In juvenile phocids, the successful transition from nursing to independent foraging is contingent upon the development of adequate diving skills within the limited time between weaning and the depletion of body reserves. Yet, because juvenile seals are unable to remain submerged for as long as adults, owing to their smaller size, higher metabolic rates, and lowered oxygen stores, their behavioral options are likely constrained. To determine how such limitations might influence foraging strategies, we studied the development of diving behavior and physiology in Weddell seal (Leptonychotes weddellii) juveniles, using a combination of time-depth recorders, satellite-linked dive recorders, and morphological and physiological measurements (mass and blood chemistry). Time-depth recorder data indicated that the average depth, duration, and frequency of dives made by pups increased rapidly in the period from birth through weaning, but slowed soon thereafter. While preweaning increases in these parameters were correlated with seal age, postweaning increases in dive capacity were gradual and were probably the result of slower changes in mass and body composition. In weaned pups and yearlings, dive frequency and time underwater increased with age and (or) mass. Despite their smaller size and lower absolute energy requirements, the amount of time juveniles spent in the water was similar to that spent by adults. However, because juveniles were unable to remain submerged as long as adults and because most foraging dives were deep, juveniles were unable to spend an equivalent amount of time at the foraging depths. This difference was evident even though juveniles dove much closer to their anaerobic threshold than did adults. These findings support the hypothesis that the foraging efficiency of younger seals is reduced relative to that of adults, owing to physiological and morphological constraints on aerobic dive duration, and suggests that low juvenile survival might result from behavioral constraints.

Physiological effects on dive patterns and foraging strategies in yearling Weddell seals (Leptonychotes weddellii)

1997 ◽  
Vol 75 (11) ◽  
pp. 1796-1810 ◽  
Author(s):  
Jennifer M. Burns ◽  
Michael A. Castellini ◽  
Jason F. Schreer
Keyword(s):  
Stepwise Regression ◽  
Dive Depth ◽  
Foraging Strategies ◽  
Diving Behavior ◽  
Physiological Effects ◽  
Morphometric Measurements ◽  
Leptonychotes Weddellii ◽  
Weddell Seals ◽  
The Mean ◽  
The Relationship

Fifteen yearling Weddell seals (Leptonychotes weddellii) were captured, measured, weighed, bled, equipped with time–depth recorders, and released to determine if diving behavior was related to physical condition. Upon recovery of the time–depth recorders, dives were classified into four types based on shape, using cluster analysis. Based on maximum depth, two groups were further subdivided, for a total of seven types. The mean and maximal dive depth, duration, and frequency were determined for each yearling for all dive types combined and for each type separately. Stepwise regression and ANOVA techniques were used to test the relationship between diving behavior and physiological and morphometric measurements. In general, half of the variation in the pooled diving behavior could be explained by body-size differences. Larger yearlings made longer and shallower dives than smaller yearlings. Dive patterns suggested that large yearlings foraged primarily on small shallow-water prey items, while small yearlings concentrated on energy-dense deep-water prey. However, the interpretation of diving behavior, foraging locations, and diet that resulted from separating individuals and dive types was very different from that based on average diving behavior. This argues against ignoring variation among individuals and using only average diving behavior when describing marine mammal dive patterns.

scholarly journals Marine mammals and Emperor penguins: a few applications of the Krogh principle

2015 ◽  
Vol 308 (2) ◽  
pp. R96-R104 ◽  
Author(s):  
Gerald Kooyman
Keyword(s):  
Marine Mammals ◽  
Blood Gases ◽  
Weddell Seal ◽  
Dive Duration ◽  
Positive Contribution ◽  
Lung Collapse ◽  
Flow Rates ◽  
Weddell Seals ◽  
Arterial Blood ◽  
Emperor Penguins

The diving physiology of aquatic animals at sea began 50 years ago with studies of the Weddell seal. Even today with the advancements in marine recording and tracking technology, only a few species are suitable for investigation. The first experiments were in McMurdo Sound, Antarctica. In this paper are examples of what was learned in Antarctica and elsewhere. Some methods employed relied on willingness of Weddell seals and emperor penguins to dive under sea ice. Diving depth and duration were obtained with a time depth recorder. Some dives were longer than an hour and as deep as 600 m. From arterial blood samples, lactate and nitrogen concentrations were obtained. These results showed how Weddell seals manage their oxygen stores, that they become reliant on a positive contribution of anaerobic metabolism during a dive duration of more than 20 min, and that nitrogen blood gases remain so low that lung collapse must occur at about 25 to 50 m. This nitrogen level was similar to that determined in elephant seals during forcible submersion with compression to depths greater than 100 m. These results led to further questions about diving mammal's terminal airway structure in the lungs. Much of the strengthening of the airways is not for avoiding the “bends,” by enhancing lung collapse at depth, but for reducing the resistance to high flow rates during expiration. The most exceptional examples are the small whales that maintain high expiratory flow rates throughout the entire vital capacity, which represents about 90% of their total lung capacity.

Diving performance of male and female Japanese Cormorants

1996 ◽  
Vol 74 (6) ◽  
pp. 1098-1109 ◽  
Author(s):  
Yutaka Watanuki ◽  
Akiko Kato ◽  
Yasuhiko Naito
Keyword(s):  
Body Mass ◽  
Dive Duration ◽  
Sexual Differences ◽  
Foraging Efficiency ◽  
Diving Behavior ◽  
Bottom Phase ◽  
Similar Proportion ◽  
Sexually Dimorphic ◽  
Surface Time ◽  
Ascent Phase

Sexual differences in the diving behavior of the sexually dimorphic Japanese Cormorant, Phalacrocorax capillatus (males are 26% heavier than females), were studied at Teuri Island, Hokkaido, using time–depth recorders. A typical dive cycle involved a rapid descent phase, a bottom phase where they remained for a while, an ascent phase, and a postdive surface phase. Depth and duration across individual birds were greater for males (15.1 ± 3.7 (mean ± SD) m, 37 ± 5 s, respectively) than those for females (7.2 ± 2.4 m, 24 ± 4 s, respectively). While submerged, females spent a similar proportion of time during the bottom phase to males, hence foraging efficiency (proportion of time at the bottom to total dive cycle time) did not differ between the sexes. No sexual differences were found in descent and ascent rates, dive bout duration, or time spent underwater per day. No significant effects of dive duration on postdive surface time were observed for either sex, indicating that birds dived within an aerobic dive limit. However, mean dive durations and maximum dive durations for individual birds were a function of body mass to the power 1.49 and 1.87, respectively, suggesting that body mass partly constrains the diving behavior of this opportunistically feeding cormorant.

Weddell seal foraging dives: comparison of free-ranging and isolated-hole paradigms

2014 ◽  
Vol 27 (1) ◽  
pp. 57-68 ◽  
Author(s):  
K.M. Madden ◽  
L.A. Fuiman ◽  
T.M. Williams ◽  
R.W. Davis
Keyword(s):  
Foraging Behaviour ◽  
Three Dimensional ◽  
Foraging Strategy ◽  
Weddell Seal ◽  
Foraging Strategies ◽  
Weddell Seals ◽  
Complex Interactions ◽  
Behaviour Changes ◽  
Free Ranging ◽  
Multiple Holes

AbstractWeddell seals are polar predators that must partition their time between many behaviours, including hunting prey at depth and breathing at the surface. Although they have been well studied, little is known about how foraging behaviour changes when access to breathing holes is restricted, such as in the isolated-hole paradigm. The current study took advantage of previously gathered data for seals diving at an isolated hole to compare with foraging behaviour of free-ranging seals that had access to multiple holes. We examined dive structure, hunting tactics, and allocation of time, locomotor activity and energy based on three-dimensional dive profiles and video imagery of prey encounters for two free-ranging and six isolated-hole seals. Midsummer foraging dives of free-ranging seals were remarkably similar to those of seals diving at an isolated hole, but there were differences in two behavioural states and the frequency of several behavioural transitions. Results indicate that seals employ an energetically more conservative foraging strategy when access to breathing holes is limited and prey are less abundant. These results highlight the importance of understanding the complex interactions between breathing hole access, prey abundance and other factors that may result in different Weddell seal foraging strategies under changing future conditions.

scholarly journals Dive Performance and Aquatic Thermoregulation of the World’s Smallest Mammalian Diver, the American Water Shrew (Sorex palustris)

2021 ◽  
Author(s):  
Roman W. Gusztak ◽  
Robert A. MacArthur ◽  
Kevin L. Campbell
Keyword(s):  
Body Temperature ◽  
Core Body Temperature ◽  
Thermal Inertia ◽  
Oxygen Storage Capacity ◽  
Dive Duration ◽  
Oxygen Storage ◽  
Foraging Efficiency ◽  
Diving Behavior ◽  
In The Wild ◽  
Total Body Oxygen

AbstractAllometry predicts that the 12–17 g American water shrew (Sorex palustris)—the world’s smallest mammalian diver—will have the highest diving metabolic rate (DMR) coupled with the lowest total body oxygen storage capacity, skeletal muscle buffering capacity, and glycolytic potential of any endothermic diver. Despite these constraints, the maximum dive time (23.7 sec) and calculated aerobic dive limit (cADL; 10.8–14.4 sec) of wild-caught water shrews match or exceed values predicted by allometry based on studies of larger-bodied divers. The mean voluntary dive time of water shrews in 3, 10, 20, and 30°C water was 5.1±0.1 sec (N=25, n=1584), with a mean maximum dive time of 10.3±0.4 sec. Only 2.3–3.9% of dives in 30 and 10°C water, respectively, exceeded the cADL. Mean dive duration, duration of the longest dive, and total time in water all decreased significantly as temperature declined, suggesting that shrews employed behavioural thermoregulation to defend against immersion hypothermia. As expected from their low thermal inertia, diving shrews had a significantly higher DMR in 10°C (8.77 mL O2 g-1 hr-1) compared to 30°C water (6.57 mL O2 g-1 hr-1). Diving behavior of radio-telemetered shrews exclusively foraging in a simulated riparian environment (3°C water) for 12- to 28-hours suggest that mean (but not maximum) dive times of water shrews in the wild may be longer than predicted from our voluntary dive trials, as the average dive duration (6.9±0.2 sec, n=257) was ∼1.75× longer than during 20-min trials with no access to food at the same water temperature. Notably, free-diving shrews in the 24-hr trials consistently elevated core body temperature by ∼1.0–1.5°C immediately prior to initiating aquatic foraging bouts, and ended these bouts when body temperature was still at or above normal resting levels (∼37.8°C). We suggest this observed pre-dive hyperthermia aids to heighten the impressive somatosensory physiology, and hence foraging efficiency, of this diminutive predator while submerged.

scholarly journals Regional Variation in Winter Foraging Strategies by Weddell Seals in Eastern Antarctica and the Ross Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Rob Harcourt ◽  
Mark A. Hindell ◽  
Clive R. McMahon ◽  
Kimberly T. Goetz ◽  
Jean-Benoit Charrassin ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Ross Sea ◽  
Weddell Seal ◽  
Foraging Strategies ◽  
Prydz Bay ◽  
Weddell Seals ◽  
Ice Concentration ◽  
Winter Foraging ◽  
Terre Adélie ◽  
The Antarctic

The relative importance of intrinsic and extrinsic determinants of animal foraging is often difficult to quantify. The most southerly breeding mammal, the Weddell seal, remains in the Antarctic pack-ice year-round. We compared Weddell seals tagged at three geographically and hydrographically distinct locations in East Antarctica (Prydz Bay, Terre Adélie, and the Ross Sea) to quantify the role of individual variability and habitat structure in winter foraging behaviour. Most Weddell seals remained in relatively small areas close to the coast throughout the winter, but some dispersed widely. Individual utilisation distributions (UDi, a measure of the total area used by an individual seal) ranged from 125 to 20,825 km2. This variability was not due to size or sex but may be due to other intrinsic states for example reproductive condition or personality. The type of foraging (benthic vs. pelagic) varied from 56.6 ± 14.9% benthic dives in Prydz Bay through 42.1 ± 9.4% Terre Adélie to only 25.1 ± 8.7% in the Ross Sea reflecting regional hydrographic structure. The probability of benthic diving was less likely the deeper the ocean. Ocean topography was also influential at the population level; seals from Terre Adélie, with its relatively narrow continental shelf, had a core (50%) UD of only 200 km2, considerably smaller than the Ross Sea (1650 km2) and Prydz Bay (1700 km2). Sea ice concentration had little influence on the time the seals spent in shallow coastal waters, but in deeper offshore water they used areas of higher ice concentration. Marine Protected Areas (MPAs) in the Ross Sea encompass all the observed Weddell seal habitat, and future MPAs that include the Antarctic continental shelf are likely to effectively protect key Weddell seal habitat.

Animal-Borne Instrumentation Systems and the Animals that Bear Them: Then (1939) and Now (2007)

2007 ◽  
Vol 41 (4) ◽  
pp. 6-8 ◽  
Author(s):  
Gerald Kooyman
Keyword(s):  
Loggerhead Turtle ◽  
Video Camera ◽  
Weddell Seal ◽  
Gps Tracking ◽  
Major Step ◽  
Mcmurdo Sound ◽  
Weddell Seals ◽  
History Of ◽  
Archival Systems ◽  
Microprocessor Technology

The history of animal-borne instrumentation is reviewed from the first basic depth gauge invented in the late 1800s, to the complex animal-borne imagery and archival systems of the present day. A major breakthrough occurred in 1964 when the first time-depth recorder was deployed on a Weddell Seal in McMurdo Sound, Antarctica. The next phase in the study of animals at sea was the use of microprocessors as archival recorders in the mid-1980s. These also were first attached to Weddell seals in McMurdo Sound. Microprocessor technology made possible the next major step of attaching a video camera housed in a submersible case (Crittercam) to a loggerhead turtle. Since the 1990s the field of “Biologging” has flourished, with new additions of satellite and GPS tracking, and resulted in three major international symposiums in the past four years (2003-2007).

scholarly journals Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Monique Ladds ◽  
David Rosen ◽  
Carling Gerlinsky ◽  
David Slip ◽  
Robert Harcourt
Keyword(s):  
Foraging Strategy ◽  
Central Place ◽  
Dive Duration ◽  
Foraging Strategies ◽  
Body Morphology ◽  
Sea Lions ◽  
Fur Seals ◽  
Adequate Food ◽  
Physiological Capacity ◽  
Total Body Oxygen

Abstract Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

Calling depth and time and frequency attributes of harp (Pagophilus groenlandicus) and Weddell (Leptonychotes weddellii) seal underwater vocalizations

2005 ◽  
Vol 83 (11) ◽  
pp. 1438-1452 ◽  
Author(s):  
Hilary B Moors ◽  
John M Terhune
Keyword(s):  
Light Condition ◽  
Weddell Seal ◽  
Harp Seal ◽  
Vertical Array ◽  
Vocal Cords ◽  
Leptonychotes Weddellii ◽  
Call Duration ◽  
Weddell Seals ◽  
Pagophilus Groenlandicus ◽  
Breeding Seasons

Harp seal (Pagophilus groenlandicus (Erxleben, 1777)) daytime calling depth during the breeding season and Weddell seal (Leptonychotes weddellii (Lesson, 1826)) daytime and nighttime calling depth during the winter and breeding seasons were investigated using a small vertical array with hydrophones placed at depths of 10 and 60 m. Rough calling depth estimates (<35 m, ~35 m, >35 m) and more accurate point depth estimates (±5–10 m in most cases) were obtained. Significantly more calls were produced at depths ≤35 m for both species. The point depth estimates indicated that the calls occurred most frequently at depths >10 m; 60% of harp seal calls and 71% of Weddell seal calls occurred at depths between 10 and 35 m. The seals called predominately within areas of the water column where light would likely penetrate, but still avoided sea-ice interference to some extent. The vocalizations did not change over depth with respect to call type, the number of elements within a call, or total call duration, or with respect to season and light condition for Weddell seals. Frequency (kHz) of calls also did not change with depth, suggesting that harp and Weddell seals control the pitch of their vocalizations with the vocal cords of the larynx.

scholarly journals Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density

2015 ◽  
Vol 1 (9) ◽  
pp. e1500469 ◽  
Author(s):  
Elliott Lee Hazen ◽  
Ari Seth Friedlaender ◽  
Jeremy Arthur Goldbogen
Keyword(s):  
Energy Intake ◽  
Prey Density ◽  
Prey Capture ◽  
Energy Gain ◽  
Foraging Strategies ◽  
Foraging Efficiency ◽  
Energetic Efficiency ◽  
Breath Hold ◽  
Balaenoptera Musculus ◽  
Blue Whales

Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency.

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