Health and condition in the adult Weddell seal of McMurdo Sound, Antarctica

Mellish, Jo‐Ann E.; Hindle, Allyson G.; Horning, Markus

doi:10.1016/j.zool.2010.11.007

Cited by 16 publications

(15 citation statements)

References 42 publications

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“…In both fall and spring, Weddell seal hematological parameters were similar to values seen in previous studies Mellish et al 2011). Only blood Hct and RBCs were lower in reproductive Weddell seals, and Hb and BV did not change seasonally.…”

Section: Discussionsupporting

confidence: 85%

Scaling matters: incorporating body composition into Weddell seal seasonal oxygen store comparisons reveals maintenance of aerobic capacities

2015

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β-hydroxyacyl CoA dehydrogenase) were likewise maintained across the year. The preservation of aerobic capacity is likely critical to foraging capabilities, so that following the molt Weddell seals can rapidly regain body mass at the start of winter foraging. In contrast, muscle lactate dehydrogenase activity, a marker of anaerobic metabolism, exhibited seasonal plasticity in this diving top predator and was lowest after the summer period of reduced activity. Total body oxygen stores Abstract Adult Weddell seals (Leptonychotes weddellii) haul-out on the ice in October/November (austral spring) for the breeding season and reduce foraging activities for ~4 months until their molt in the austral fall (January/February). After these periods, animals are at their leanest and resume actively foraging for the austral winter. In mammals, decreased exercise and hypoxia exposure typically lead to decreased production of O 2 -carrying proteins and muscle wasting, while endurance training increases aerobic potential. To test whether similar effects were present in marine mammals, this study compared the physiology of 53 post-molt female Weddell seals in the austral fall to 47 pre-breeding females during the spring in McMurdo Sound, Antarctica. Once body mass and condition (lipid) were controlled for, there were no seasonal changes in total body oxygen (TBO 2 ) stores. Within each season, hematocrit and hemoglobin values were negatively correlated with animal size, and larger animals had lower mass-specific TBO 2 stores. But because larger seals had lower mass-specific metabolic rates, their calculated aerobic dive limit was similar to smaller seals. Indicators of muscular efficiency, myosin heavy chain composition, myoglobin concentrations, and aerobic enzyme activities (citrate synthase and Keywords

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Section: Discussionsupporting

confidence: 85%

Scaling matters: incorporating body composition into Weddell seal seasonal oxygen store comparisons reveals maintenance of aerobic capacities

2015

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“…Lateral axilla also displayed the highest skin temperatures and heat loss in water of all sites excepting head (Fig. 3), despite its association with the greatest regional blubber depth measured in this species [34]. Together, this indicates that axilla may be an important site for obligate heat loss, perhaps reflecting its proximity to the body core.…”

Section: Regional Heat Fluxmentioning

confidence: 90%

“…Sedated seals were weighed with a tripod and suspended scale (±0.5 kg, San Diego Scale). Blubber depth was measured at 10 body locations by imaging ultrasound [13,33,34]. Body surface area and volume were collected for each individual by photogrammetry.…”

Section: Additional Data Collectedmentioning

confidence: 99%

Estimating total body heat dissipation in air and water from skin surface heat flux telemetry in Weddell seals

2015

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Background: Accurate estimates of thermoregulatory costs in air and water are necessary to predict the impacts of changing habitats to individuals and populations of ice-obligate seals. Investigations that would provide such estimates of thermoregulatory physiology over natural activities in free-ranging marine mammals have been limited. This study describes a biotelemetry method for measuring skin surface heat flux in free-ranging Weddell seals. These data are then applied to estimations of thermoregulatory heat dissipation from multiple point measurements.Results: Data loggers collecting skin surface heat flux telemetry at four body locations (head, neck, axilla and flank) from 40 free-ranging Weddell seals were deployed and recovered over periods of 1-13 days in Erebus Bay, Antarctica. We derive equations for estimating total body heat dissipation from these point measurements and demonstrate the subsequent calculation of heat dissipated from obligate thermoregulatory costs. Heat lost to air or water was described by heat flux sensor data extrapolated across the whole-body surface, as informed by skin surface infrared thermal patterns. Heat lost directly to the ice surface during haul-out was best described by physical features of the seal, rather than environmental variables. Heat flux inputs from the four sensors could be reduced to two principal components, and corresponding regressions indicated that the axilla and flank sensors were most correlated with total body heat dissipation in air and water. Variability in head sensor heat flux was least described by the two principal components. Conclusions:This method can be used to estimate total body heat dissipation during daily activities in marine mammals, and under steady-state conditions, it can be used to identify obligate thermoregulatory heat costs. Ultimately this type of data will provide relevant empirical information for parameterizing models of thermoregulatory energetics in ice-obligate seals, which may improve our ability to predict outcomes of altered ice conditions at high latitudes.

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“…In recent years, ultrasound imaging has become a common method to accurately and noninvasively measure blubber depth in pinnipeds, as multiple measures can be obtained in mere minutes (e.g., Mellish et al 2004Mellish et al , 2011Noren and Mangel 2004 to determine individual mass, but not discrete body composition. In this instance, they utilized a length to girth index with great success for estimating mass, but was not tested for estimating elements of body composition, as was the case with others (Shero et al 2014).…”

Section: Discussionmentioning

confidence: 99%

“…This procedure, however, can be both costly and time consuming for larger animal species and therefore unrealistic in some circumstances. Alternative nonlethal methods, such as bioelectrical impedance analysis, have found varied levels of success (Arnould 1995;Tierney et al 2001); however, the most prevalent indirect methods for pinnipeds rely on various morphometricderived condition indices that vary by species (Castellini and Calkins 1993;Trites and Jonker 2000;Noren and Mangel 2004;Castellini et al 2009;Mellish et al 2011). There has been increasing recognition of the need for continued development of measures of condition (e.g., Beck et al 1993;Pitcher et al 2000;Castellini et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Weighing our measures: approach-appropriate modeling of body composition in juvenile Steller sea lions (Eumetopias jubatus)

2015

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While many approaches to modeling body condition exist, ranging from arbitrary morphometric indices to sophisticated cone modeling, few approaches have attempted to develop a standardized, simplified method for determining total body fat and protein in otariids. Our goal was to develop a method for predicting the body condition of juvenile Steller sea lions (Eumetopias jubatus (Schreber, 1776)) using simple morphometrics such as measurements of girth, length, mass, and blubber depth. We compared a candidate set of models to determine which metrics best predicted total body water (TBW) measures obtained by deuterium isotope dilution. Furthermore, we used AIC c (Akaike's information criterion corrected for small sample size) model selection methods and cross-validation to choose and validate the best suite of predictors. TBW was best predicted by a model that included mass, standard length, axial girth with the addition of blubber depths on the lateral side of the neck and dorsal surface of the hip. The results presented here show that blubber depth is an important addition to modeling body composition and may improve upon nonlethal, population-level estimates of nonisotopically derived values of TBW in juvenile Steller sea lions. Additionally, our models present a model development framework for other research efforts for use in determining body condition in otariids.Résumé : S'il existe de nombreuses approches de modélisation de l'état d'embonpoint, allant d'indices morphométriques arbitraires à la modélisation conique de pointe, peu d'auteurs ont tenté d'élaborer une méthode simplifiée normalisée pour déterminer les lipides et protéines corporels totaux d'otariidés. Notre objectif consistait à mettre au point une méthode pour prédire l'état d'embonpoint chez des otaries de Steller (Eumetopias jubatus (Schreber, 1776)) juvéniles à l'aide de paramètres morphométriques simples tels que des mesures de la circonférence de la poitrine, de la longueur, de la masse et de la profondeur de la couche de graisse sous-cutanée. Nous avons comparé un ensemble de modèles possibles afin de déterminer quels paramètres prédisent le mieux les mesures de l'eau corporelle totale (ECT) obtenues par dilution du deutérium. Nous avons en outre utilisé des méthodes de sélection de modèles basées sur le critère d'AIC c (l'information d'Akaike corrigé pour la petite taille de l'échantillon), ainsi que la validation croisée pour sélectionner et valider le meilleur ensemble de prédicteurs. Le meilleur prédicteur de l'ECT est un modèle qui intègre la masse, la longueur standard, la circonférence axiale avec l'ajout des profondeurs de la couche de graisse du côté latéral du cou et sur la surface dorsale de la hanche. Les résultats présentés montrent que la profondeur de la couche de graisse est un ajout important à la modélisation de la composition corporelle et pourrait améliorer les estimations basées sur des approches non létales à l'échelle de la population des valeurs d'ECT ne reposant pas sur des méthodes isotopiques, chez les otaries de ...

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Health and condition in the adult Weddell seal of McMurdo Sound, Antarctica

Cited by 16 publications

References 42 publications

Scaling matters: incorporating body composition into Weddell seal seasonal oxygen store comparisons reveals maintenance of aerobic capacities

Scaling matters: incorporating body composition into Weddell seal seasonal oxygen store comparisons reveals maintenance of aerobic capacities

Estimating total body heat dissipation in air and water from skin surface heat flux telemetry in Weddell seals

Weighing our measures: approach-appropriate modeling of body composition in juvenile Steller sea lions (Eumetopias jubatus)

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