Basic biochemical data on blood from antarctic Weddell seals (Leptonychotes weddelli): ions, lipids, enzymes, serum proteins and thyroid hormones (original) (raw)
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2009
The demography of Weddell seals in eastern McMurdo Sound, Antarctica, has been well studied during the past three decades (e.g. Stirling 1971; Siniff et al. 1977; Testa and Siniff 1987; Hastings and Testa 1998; Gelatt et al. 2001). Detailed life-history data are available on thousands of seals tagged as pups in McMurdo Sound, making this population a rich resource for wildlife health studies because health parameters can be evaluated in the light of reproductive histories and genetic relationships of several generations of tagged seals. Recently, evidence of exposure to diseases generally associated with domestic animals and feral wildlife has been detected in Antarctic wildlife (Austin and Webster 1993; Olsen et al. 1996; Gardner et al. 1997; Retamal et al. 2000; Foster et al. 2002) and this has generated concern and debate regarding the risks of disease introduction to Antarctic wildlife. Antibodies to viruses that have caused large die-offs in phocids in other areas of the world ...
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2005
Blood protein analysis including total serum protein and albumin by chemical methods, fibrinogen estimation and serum protein electrophoresis (SPE) was performed on the leopard seal, Hydrurga leptonyx. The most commonly observed SPE pattern was eight fractions designated albumin, a 1a , a 1b , a 2a , a 2b , h 1 , h 2 and g-globulin. Significantly higher total serum protein and albumin concentrations, as determined by chemical methods, and significantly higher a 2 -globulin concentrations, determined by SPE, were seen in free-ranging male seals compared to females, whilst significantly higher h-globulin concentrations were seen in female seals. Season of sampling influenced fibrinogen and h 2 -globulin concentrations, whereas there were no significant differences in any protein concentrations with moult status. Qualitative comparison of SPE traces of leopard seals in Antarctica with ''sick'' individuals in NSW, Australia revealed obvious differences, as did quantitative comparison of protein concentrations where differences in a 1 , a 2 , h 1 , h 2 , and g-globulin concentrations were seen. These findings suggest that SPE is a useful tool for investigating serum proteins in the leopard seal, with applications for the investigation of ''sick'' individuals and the assessment of variation in homeostasis. This technique could also be used to identify the presence of environmental stressors, subclinical disease and physiological variation within specific seal populations. D
Journal of Experimental Biology, 2010
Our objective was to elucidate age-related changes in lipids associated with skeletal muscle of Weddell seals and to suggest possible physiological implications. Muscle biopsies were collected from pups, juveniles and adults in McMurdo Sound, Antarctica and analyzed for intramuscular lipid (IML) and triacylglyceride (IMTG) amounts, fatty acid groups, as well as individual fatty acid profiles. The results from this study suggest a switch from primarily saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) in the skeletal muscle of young pups to increases in polyunsaturated fatty acids (PUFAs) as the percentage of blubber increases, resulting in possible thermoregulatory benefits. As Weddell pups continue to develop into juveniles, fatty acids associated with the skeletal muscle changes such that MUFA levels are relatively higher, which may be in response to energy depletion associated with their restricted diving ability and rapid growth. As juveniles transform into adults, a reduction in n-3 PUFA levels in the muscle as the percentage of blubber increases may be indicative of a trigger to prepare for deep diving or could be a mechanism for oxygen conservation during long-duration dives. We speculate that the observed change in lipids associated with the skeletal muscle of Weddell seals is related to ontogenetic differences in thermoregulation and locomotion.
Journal of Wildlife Diseases, 2012
Information on health parameters, such as antibody prevalences and serum chemistry that can reveal exposure to pathogens, disease, and abnormal physiologic conditions, is scarce for Antarctic seal species. Serum samples from Antarctic fur seals (Arctocephalus gazella, n588) from Bouvetøya (2000-2001 and 2001-2002), and from Weddell seals (Leptonychotes weddellii, n520), Ross seals (Ommatophoca rossii, n520), and crabeater seals (Lobodon carcinophagus, n59) from the pack-ice off Queen Maud Land, Antarctica (2001) were analyzed for enzyme activity, and concentrations of protein, metabolites, minerals, and cortisol. Adult Antarctic fur seal males had elevated levels of total protein (range 64-99g/l) compared to adult females and pups (range 52-79 g/l). Antarctic fur seals had higher enzyme activities of creatine kinase, lactate dehydrogenase, and amylase, compared to Weddell, Ross, and crabeater seals. Antibodies against Brucella spp. were detected in Weddell seals (37%), Ross seals (5%), and crabeater seals (11%), but not in Antarctic fur seals. Antibodies against phocine herpesvirus 1 were detected in all species examined (Antarctic fur seals, 58%; Weddell seals, 100%; Ross seals, 15%; and crabeater seals, 44%). No antibodies against Trichinella spp., Toxoplasma, or phocine distemper virus (PDV) were detected (Antarctic fur seals were not tested for PDV antibodies). Antarctic seals are challenged by reduced sea ice and increasing temperatures due to climate change, and increased anthropogenic activity can introduce new pathogens to these vulnerable ecosystems and represent a threat for these animals. Our data provide a baseline for future monitoring of health parameters of these Antarctic seal species, for tracking the impact of environmental, climatic, and anthropogenic changes in Antarctica over time.
Temporal variation in isotopic composition and diet of Weddell seals in the western Ross Sea
Deep-sea Research Part Ii-topical Studies in Oceanography, 2017
Weddell seals (Leptonychotes weddellii) are important predators in the Antarctic marine ecosystem, yet little is known about their diet. Previous studies have used scat and stomach content analyses to examine Weddell seal diet, however, these methods are biased towards prey with indigestible hard parts. To provide a more complete picture of their diet, we analyzed the stable isotope composition (δ 13 C and δ 15 N values) of red blood cells (RBC, n ¼96, representing a time scale of weeks to months) and vibrissae (n ¼45, representing months to a year) collected over a three year period (2010-2012). Our objectives were to (1) examine isotopic variation in relation to Weddell seal mass, sex, season, location, percent lipid, and age, and (2) quantify the contribution of prey items to overall diet. Body mass was a significant predictor of δ 13 C and δ 15 N values for both tissues, though the strength and direction of the relationship varied by year. The prey group consisting of Pleurogramma antarcticum and Trematomus newnesi was found to be an important dietary component, but its proportional contribution to Weddell seal diet varied with the timeframe represented by each tissue type [median RBC (range): 59.2% (40.2-8 1.1%); median mean vibrissae (range): 69.3% (43.9-89.6%)]. Results from mixing models ran for each seal indicate individual variation in diet. Overall, this study presents novel information on the isotopic variation and diet of Weddell seals over two time scales and provides insight into the feeding ecology of an important Antarctic predator.
Canadian Journal of Zoology, 2002
Stable nitrogen and carbon isotope ratios (13C/12C and 15N/14N, respectively) of plasma, serum, clotted red blood cells, and unclotted red blood cells from six captive northern fur seals (Callorhinus ursinus) and two fish species in their diet, Atlantic herring (Clupea harengus) and Icelandic capelin (Mallotus villosus), were measured. The δ15N values from the fur seal blood components ranged from 15.5 ± 0.1 (mean ± SE; all RBCs) to 16.7 ± 0.1 (plasma), and δ13C values ranged from 18.3 ± 0.1 (serum) to 17.5 ± 0.1 (clotted RBCs). Fur seal blood components had higher δ15N and δ13C values than their diet. Mean enrichments of 15N between fur seal RBCs and plasma/serum and their prey were +4.1 and +5.2, respectively, while mean 13C enrichments were +0.6 (serum), +1.0 (plasma), and +1.3 to +1.4 (all RBCs). Fur seal blood components did not differ in δ15N or δ13C between the sexes. One female (Baabs) was pregnant at the time of sampling and was resampled 4 months later, when she ...
General and Comparative Endocrinology, 2004
This study aimed to verify the serum leptin concentration during the terrestrial phase of the Southern elephant seal (Mirounga leonina) on Elephant Island (South Shetlands, Antarctica). Sera from 25 adult Southern elephant seals were analyzed. Leptin concentration was determined using the 125 I radioimmunoassay method. Total protein, triglycerides, and cholesterol concentration were measured by spectrophotometric methods. Seals were grouped by sex and their physiological status (reproducing or molting seals). In reproducing seals, serum concentrations of leptin, total protein, triglycerides, and cholesterol were, respectively, 9.
Polar Biology, 1998
The diet of adult and juvenile Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica, was determined from both scat and stable isotope analyses, to ascertain if foraging behavior varied with age, season, or diving pattern. Scats were collected over 6 years and recovered hard parts identi®ed. Stable carbon and nitrogen isotope values were determined for seal blood samples and potential prey items and used to identify primary prey species and assess trophic interactions. Pleuragramma antarcticum remains were recovered from between 70 and 100% of the scats, and there was little evidence for inter-annual or age-speci®c variation in foraging behavior. However, stable isotope and dive data analyses indicated that while most seals foraged predominantly on pelagic ®sh and squid, some juveniles concentrated on shallow benthic Trematomus spp. Combining these three methods permitted ®rm conclusions about diet and foraging behavior to be drawn.