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Peter D Nichols - One of the best experts on this subject based on the ideXlab platform.
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vertical distribution of lipids fatty acids and organochlorine contaminants in the Blubber of southern hemisphere humpback whales megaptera novaeangliae
Marine Environmental Research, 2014Co-Authors: Courtney Waugh, Peter D Nichols, Martin Schlabach, Michael J Noad, Susan Bengtson NashAbstract:Persistent organic pollutants (POPs), such as toxic lipophilic organochlorine (OC) compounds, accumulate in the Blubber tissue of marine mammals. Toxicological sampling methods most frequently target only the superficial Blubber layer. Vertical distribution of these contaminants through the Blubber mantle may, however, not be homogenous and could reflect any dissemination of lipids and fatty acids (FAs). It is therefore critical to assess stratification patterns in a species of interest as a quality control measure for interpretation of toxicological data. Here, we analysed and compared the distribution of lipids, FAs, and OCs in the outermost and innermost Blubber layer of southern hemisphere humpback whales. FA stratification was evident for short-chain (≤18) monounsaturated fatty acids (SC-MUFA), which were concentrated in the outer layer, consistent with the thermoregulatory role of this Blubber layer. This stratification was, however, not reflected in OC distribution, which was similar in the inner and outer Blubber layers of male humpback whales. By comparison, a noticeable gradient in total Blubber lipid from the outer to the inner layer was observed in two lactating females, which coincided with higher lipid normalised contaminant levels in the inner layer. This study contains the most comprehensive assessment of humpback whale Blubber stratification to date, however, further investigation of biological and ecological influencing factors is required.
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differential mobilization of Blubber fatty acids in lactating weddell seals evidence for selective use
Physiological and Biochemical Zoology, 2008Co-Authors: Kathryn E Wheatley, Peter D Nichols, Mark A Hindell, Robert Harcourt, Corey J A BradshawAbstract:Abstract A major source of energy during lactation in mammals is provided through the mobilization of Blubber fatty acids (FAs). We investigated the extent to which FAs were mobilized to support both maternal metabolic requirements and milk production in the Weddell seal and how this was reflected in the FA composition of the pup’s Blubber at the end of lactation (EL). FA composition of postpartum female Blubber was similar in the 2 yr of study (2002 and 2003) but differed markedly by EL. Pup Blubber FAs (at EL) were also different between years and did not match that of the mother’s milk or Blubber. Milk FA composition changed during lactation, which may have been a reflection of an increase in pup energy demands at different stages of development. In addition, there was evidence of feeding by some females during lactation, with higher levels of some FAs in the milk than in the Blubber. Our results indicate that differential mobilization of FAs occurred in lactating Weddell seals and that this was relate...
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variation in the fatty acid composition of Blubber in cape fur seals arctocephalus pusillus pusillus and the implications for dietary interpretation
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2005Co-Authors: John P Y Arnould, Peter D Nichols, Matthew M Nelson, W H OosthuizenAbstract:Analysis of the fatty acid (FA) composition of Blubber is a valuable tool in interpreting the diet of marine mammals. This technique is based on the principle that particular FA present in prey can be incorporated largely untransformed into predator adipose tissue stores, thereby providing biochemical signatures with which to identify prey species. Several studies of phocid seals and cetaceans have documented vertical stratification in the FA composition of Blubber such that inferences about diet may vary greatly depending on the layer of the Blubber that is analysed. It is not known whether Blubber in otariid seals (fur seals and sea lions) also displays vertical stratification in FA composition. Furthermore, it is not known whether the FA composition of Blubber is uniform in these species. In the present study, the vertical and regional variation in FA composition of Blubber was investigated in seven adult female Cape fur seals (Arctocephalus pusillus pusillus). The proportion of monounsaturated fatty acids (MUFA) was greater in the outer (43.6±1.3%) than inner portion (40.9±1.2%; t20=5.59, P<0.001) whereas the proportions were greater in the inner than outer portions for saturated fatty acids (23.6±0.5% and 21.9±0.6%, respectively, t20 = 5.31, P<0.001) and polyunsaturated fatty acids (PUFA, 35.5±0.7% and 34.5±0.7%, respectively, t20 = 3.81, P < 0.001). There was an inverse relationship between MUFA and PUFA in the Blubber, independent of sampling location. In addition, with the exception of the inner portion from non-lactating females, Blubber from the mammary area had the highest proportions of 18:1ω9c and total MUFA, followed by Blubber from the rump and neck, suggesting that the deposition and mobilisation of Blubber lipids may not be uniform around the body in otariid seals. These results support the need for Blubber tissue to be sampled from the same site on animals, and to the full depth of the Blubber layer, to minimise variation in FA profiles that could occur if different sites and depths were sampled. Such standardisation of sampling will further aid in interpreting diet in otariid seals using the FA Signature Analysis approach.
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vertical stratification of fatty acids in the Blubber of southern elephant seals mirounga leonina implications for diet analysis
Comparative Biochemistry and Physiology B, 2003Co-Authors: Narelle J Best, Corey J A Bradshaw, Mark A Hindell, Peter D NicholsAbstract:Fatty acid signature analysis (FASA) is a powerful ecological tool that uses essential fatty acids (FA) from the tissues of animals to indicate aspects of diet. However, the presence of vertical stratification in FA distribution throughout Blubber complicates the application of FASA to marine mammals. Blubber biopsy samples were collected from adult female southern elephant seals (Mirounga leonina) from Macquarie Island (n=11), and Blubber cores were divided into inner and outer sections to determine the degree to which the Blubber layer was stratified in FA composition, we found 19 FA from both Blubber layers in greater than trace amounts (>0.5%). The inner and outer Blubber layers could be separated using principal components analysis based on the relative proportion of FA in each layer. Dietary polyunsaturated fatty acids (PUFA) were also observed in significantly higher proportions in the inner Blubber layer. Due to the degree of FA stratification in southern elephant seals, we concur with other marine mammal studies that sampling only the outer Blubber layer will result in a loss of recently accumulated information regarding diet structure (as indicated by ‘surplus’ PUFA from the diet). This finding suggests that differential mobilization/deposition of certain FA may result in a modified signature from prey to predator. Thus, sampling animals to recover the inner Blubber layer is important for studies attempting to describe aspects of marine mammal diet. This can be achieved in animals such as pinnipeds where the whole Blubber layer can be readily sampled.
Cathy Debier - One of the best experts on this subject based on the ideXlab platform.
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persistent organic pollutant burden experimental pop exposure and tissue properties affect metabolic profiles of Blubber from gray seal pups
Environmental Science & Technology, 2018Co-Authors: Kelly J Robinson, Cathy Debier, Jean-pierre Thomé, Ailsa J Hall, Gauthier Eppe, Kimberley A BennettAbstract:Persistent organic pollutants (POPs) are toxic, ubiquitous, resist breakdown, bioaccumulate in living tissue, and biomagnify in food webs. POPs can also alter energy balance in humans and wildlife. Marine mammals experience high POP concentrations, but consequences for their tissue metabolic characteristics are unknown. We used Blubber explants from wild, gray seal (Halichoerus grypus) pups to examine impacts of intrinsic tissue POP burden and acute experimental POP exposure on adipose metabolic characteristics. Glucose use, lactate production, and lipolytic rate differed between matched inner and outer Blubber explants from the same individuals and between feeding and natural fasting. Glucose use decreased with Blubber dioxin-like PCBs (DL-PCB) and increased with acute experimental POP exposure. Lactate production increased with DL-PCBs during feeding, but decreased with DL-PCBs during fasting. Lipolytic rate increased with Blubber dichlorodiphenyltrichloroethane and its metabolites (DDX) in fasting anim...
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Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants
Science of The Total Environment, 2015Co-Authors: Sarah H Peterson, Daniel E Crocker, Cathy Debier, Alin C Dirtu, Govindan Malarvannan, Adrian Covaci, Lisa K Schwarz, Michael G. Peterson, Daniel P CostaAbstract:As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in Blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately sevenmonthlong foraging trip.Formales,we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females,we calculated Blubber burdens for all compounds. The highest POP concentrations in males and females were found for ΣDDTs andΣPCBs. In Blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females,ΣDDT andΣPBDEs were highly correlated in Blubber and serum.While ΣPCBs were highly correlatedwithΣDDTs andΣPBDEs in Blubber and serum formales,ΣPCBs showed weaker correlationswith both compounds in females. As females gainedmasswhile foraging, concentrations of nearly all POPs in inner and outer Blubber significantly decreased; however, the absolute burden in Blubber significantly increased, indicating ingestion of contaminantswhile foraging. Additionally,we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences inΣDDTs,ΣPBDEs, MeO-BDE 47, as well as the ratio ofΣDDTs toΣPCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations ofΣDDTs and ΣPBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in 13C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.
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mobilisation of Blubber fatty acids of northern elephant seal pups mirounga angustirostris during the post weaning fast
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015Co-Authors: Caroline Louis, Daniel E Crocker, Laurent Perdaens, Stephanie Suciu, Stephen K Tavoni, Cathy DebierAbstract:Northern elephant seal pups were longitudinally sampled at Ano Nuevo State Reserve during the post-weaning fast, in order to evaluate the changes of fatty acid (FA) profiles in serum as well as in the inner and outer layers of Blubber. The major FAs of inner and outer Blubber layers were broadly similar to those found in NES maternal milk previously measured, suggesting a direct deposit of dietary FAs in the Blubber during the suckling period. The outer Blubber layer contained more medium-chain monounsaturated FAs that contribute in keeping the fluidity of this tissue at cold temperatures. It was compensated by higher proportions of saturated FAs in the inner Blubber layer. The FA signature of inner Blubber, the layer that is mainly mobilised during energy deprivation, slightly differed from the signature of serum. There were greater proportions of medium-chain saturated FAs and ω-6 polyunsaturated FAs, and lower proportions of long-chain saturated FAs, medium-chain monounsaturated FAs and long-chain monounsaturated FAs in serum as compared to inner Blubber. We also demonstrated that lipophilicity is the main factor governing the mobilisation of FAs from Blubber. The least lipophilic FAs were preferentially hydrolysed from Blubber, leading to an enrichment of the more lipophilic FAs in this tissue with the progression of the fast. The expression levels of HSL and ATGL, which are two enzymes involved in the lipolytic process, remained stable during the post-weaning fast. This suggests that the pups have developed the enzymatic mechanisms for an efficient lipolysis as soon as the first week of fast.
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mobilisation of lipophilic pollutants from Blubber in northern elephant seal pups mirounga angustirostris during the post weaning fast
Environmental Research, 2014Co-Authors: Caroline Louis, Daniel E Crocker, Alin C Dirtu, Marie Stas, Yves Guiot, Govindan Malarvannan, Daniel P Costa, Adrian Covaci, Cathy DebierAbstract:Northern elephant seals (NES) (Mirounga angustirostris) from the Ano Nuevo State Reserve (CA, USA) were longitudinally sampled during the post-weaning fast in order to study the mobilisation and redistribution of various classes of persistent organic pollutants (POPs), such as polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB) between Blubber and blood. Inner and outer Blubber layers were analysed separately. Organohalogenated compounds were detected in all Blubber samples in the decreasing order of their concentrations: p,p′-DDE>PCBs⪢HCB>PBDEs. The concentrations of all studied compounds were homogeneously distributed in the Blubber layer at early fast, since the concentrations of POPs were statistically not different in the inner and outer layers. With the progression of the fast, the concentrations of PBDEs, PCBs and p,p′-DDE increased more sharply in inner Blubber than in outer Blubber. As a result, their levels became significantly higher in inner Blubber as compared to outer Blubber at late fast. The rise of pollutant concentrations in Blubber might result from a less efficient mobilisation than triglycerides and/or a reuptake by adipocytes of some of the pollutants released into the circulation. The mobilisation of pollutants from Blubber was higher at late fast. An increase of pollutant concentrations was observed in serum between early and late fast. Lower halogenated congeners (i.e. tetra-CBs) were present in higher proportions in serum, whereas the higher halogenated congeners (i.e. hepta-CBs) were mainly found in the inner and outer Blubber layers. The transfer ratios of both PBDEs and PCBs from inner Blubber to serum decreased with the number of chlorine and bromine atoms. In addition, the distribution of both types of compounds between serum and Blubber was strongly influenced by their lipophilic character (log Kow values), with more lipophilic compounds being less efficiently released from Blubber to serum.
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differential changes of fat soluble vitamins and pollutants during lactation in northern elephant seal mother pup pairs
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2012Co-Authors: Cathy Debier, Daniel E Crocker, Dorian S Houser, Marie Vanden Berghe, Melinda A Fowler, Eric Mignolet, Tanguy De Tillesse, Jeanfrancois Rees, Jean-pierre Thomé, Yvan LarondelleAbstract:We investigated the changes of vitamins A and E as well as PCBs and DDTs during lactation in northern elephant seal (Mirounga angustirostris) mother-pup pairs. On average, milk vitamin A concentrations were 6 times higher during late lactation than during early lactation, a pattern that differs dramatically from terrestrial mammals. Vitamin A concentrations also significantly increased in the inner Blubber throughout lactation, whereas they remained constant in the outer Blubber. Similar dynamics were observed for PCBs and DDTs in maternal Blubber and milk. Blubber appears to be an important storage site for vitamin A and organochlorines in seals and a direct transfer of those molecules to the mammary gland may occur. The dynamics of vitamin A, PCBs and DDTs differed from those of vitamin E. There was a significant drop in milk vitamin E concentrations between early and late lactation, which is the usual pattern observed in terrestrial mammals. The dynamics of vitamin E in the Blubber layers also differed from those of vitamin A, suggesting different mechanisms of mobilization and transfer into the milk.
Daniel E Crocker - One of the best experts on this subject based on the ideXlab platform.
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Blubber transcriptome response to acute stress axis activation involves transient changes in adipogenesis and lipolysis in a fasting adapted marine mammal
Scientific Reports, 2017Co-Authors: Jane Khudyakov, Cory D Champagne, L M Meneghetti, Daniel E CrockerAbstract:Stress can compromise an animal’s ability to conserve metabolic stores and participate in energy-demanding activities that are critical for fitness. Understanding how wild animals, especially those already experiencing physiological extremes (e.g. fasting), regulate stress responses is critical for evaluating the impacts of anthropogenic disturbance on physiology and fitness, key challenges for conservation. However, studies of stress in wildlife are often limited to baseline endocrine measurements and few have investigated stress effects in fasting-adapted species. We examined downstream molecular consequences of hypothalamic-pituitary-adrenal (HPA) axis activation by exogenous adrenocorticotropic hormone (ACTH) in Blubber of northern elephant seals due to the ease of Blubber sampling and its key role in metabolic regulation in marine mammals. We report the first phocid Blubber transcriptome produced by RNAseq, containing over 140,000 annotated transcripts, including metabolic and adipocytokine genes of interest. The acute response of Blubber to stress axis activation, measured 2 hours after ACTH administration, involved highly specific, transient (lasting <24 hours) induction of gene networks that promote lipolysis and adipogenesis in mammalian adipocytes. Differentially expressed genes included key adipogenesis factors which can be used as Blubber-specific markers of acute stress in marine mammals of concern for which sampling of other tissues is not possible.
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Blubber cortisol qualitatively reflects circulating cortisol concentrations in bottlenose dolphins
Marine Mammal Science, 2017Co-Authors: Cory D Champagne, Daniel E Crocker, Nicholas M Kellar, Samuel K Wasser, Rebecca K Booth, Marisa L Trego, Dorian S HouserAbstract:Stress hormones, released into circulation as a consequence of disturbance, are classically assayed from blood samples but may also be detected in a variety of matrices. Blubber and fecal samples can be remotely collected from free-ranging cetaceans without the confounding hormone elevations associated with chase, capture, and handling required to collect blood samples. The relationship between cortisol concentrations in circulation with that of Blubber and feces, however, is unknown. To assess these associations, we elevated cortisol by orally administering hydrocortisone for five days in five bottlenose dolphins. Voluntary blood and fecal samples were collected daily; Blubber biopsies were collected on day one, just prior to hydrocortisone administration, and days three and five of hydrocortisone administration. We evaluated subsequent changes in several circulating stress hormones as well as cortisol and glucocorticoid metabolites in Blubber and feces, respectively. There was a significant association between cortisol levels in serum and in Blubber (F1,12.7 = 14.3, P < 0.01, mR2 = 0.57) despite substantial variability in Blubber cortisol levels. Counterintuitively, fecal cortisol metabolite levels were inversely related to serum cortisol. The relationship between serum and Blubber cortisol levels suggests Blubber samples from remote sampling may be useful to detect stress loads in this species.
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Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants
Science of The Total Environment, 2015Co-Authors: Sarah H Peterson, Daniel E Crocker, Cathy Debier, Alin C Dirtu, Govindan Malarvannan, Adrian Covaci, Lisa K Schwarz, Michael G. Peterson, Daniel P CostaAbstract:As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in Blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately sevenmonthlong foraging trip.Formales,we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females,we calculated Blubber burdens for all compounds. The highest POP concentrations in males and females were found for ΣDDTs andΣPCBs. In Blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females,ΣDDT andΣPBDEs were highly correlated in Blubber and serum.While ΣPCBs were highly correlatedwithΣDDTs andΣPBDEs in Blubber and serum formales,ΣPCBs showed weaker correlationswith both compounds in females. As females gainedmasswhile foraging, concentrations of nearly all POPs in inner and outer Blubber significantly decreased; however, the absolute burden in Blubber significantly increased, indicating ingestion of contaminantswhile foraging. Additionally,we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences inΣDDTs,ΣPBDEs, MeO-BDE 47, as well as the ratio ofΣDDTs toΣPCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations ofΣDDTs and ΣPBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in 13C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.
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mobilisation of Blubber fatty acids of northern elephant seal pups mirounga angustirostris during the post weaning fast
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015Co-Authors: Caroline Louis, Daniel E Crocker, Laurent Perdaens, Stephanie Suciu, Stephen K Tavoni, Cathy DebierAbstract:Northern elephant seal pups were longitudinally sampled at Ano Nuevo State Reserve during the post-weaning fast, in order to evaluate the changes of fatty acid (FA) profiles in serum as well as in the inner and outer layers of Blubber. The major FAs of inner and outer Blubber layers were broadly similar to those found in NES maternal milk previously measured, suggesting a direct deposit of dietary FAs in the Blubber during the suckling period. The outer Blubber layer contained more medium-chain monounsaturated FAs that contribute in keeping the fluidity of this tissue at cold temperatures. It was compensated by higher proportions of saturated FAs in the inner Blubber layer. The FA signature of inner Blubber, the layer that is mainly mobilised during energy deprivation, slightly differed from the signature of serum. There were greater proportions of medium-chain saturated FAs and ω-6 polyunsaturated FAs, and lower proportions of long-chain saturated FAs, medium-chain monounsaturated FAs and long-chain monounsaturated FAs in serum as compared to inner Blubber. We also demonstrated that lipophilicity is the main factor governing the mobilisation of FAs from Blubber. The least lipophilic FAs were preferentially hydrolysed from Blubber, leading to an enrichment of the more lipophilic FAs in this tissue with the progression of the fast. The expression levels of HSL and ATGL, which are two enzymes involved in the lipolytic process, remained stable during the post-weaning fast. This suggests that the pups have developed the enzymatic mechanisms for an efficient lipolysis as soon as the first week of fast.
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mobilisation of lipophilic pollutants from Blubber in northern elephant seal pups mirounga angustirostris during the post weaning fast
Environmental Research, 2014Co-Authors: Caroline Louis, Daniel E Crocker, Alin C Dirtu, Marie Stas, Yves Guiot, Govindan Malarvannan, Daniel P Costa, Adrian Covaci, Cathy DebierAbstract:Northern elephant seals (NES) (Mirounga angustirostris) from the Ano Nuevo State Reserve (CA, USA) were longitudinally sampled during the post-weaning fast in order to study the mobilisation and redistribution of various classes of persistent organic pollutants (POPs), such as polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB) between Blubber and blood. Inner and outer Blubber layers were analysed separately. Organohalogenated compounds were detected in all Blubber samples in the decreasing order of their concentrations: p,p′-DDE>PCBs⪢HCB>PBDEs. The concentrations of all studied compounds were homogeneously distributed in the Blubber layer at early fast, since the concentrations of POPs were statistically not different in the inner and outer layers. With the progression of the fast, the concentrations of PBDEs, PCBs and p,p′-DDE increased more sharply in inner Blubber than in outer Blubber. As a result, their levels became significantly higher in inner Blubber as compared to outer Blubber at late fast. The rise of pollutant concentrations in Blubber might result from a less efficient mobilisation than triglycerides and/or a reuptake by adipocytes of some of the pollutants released into the circulation. The mobilisation of pollutants from Blubber was higher at late fast. An increase of pollutant concentrations was observed in serum between early and late fast. Lower halogenated congeners (i.e. tetra-CBs) were present in higher proportions in serum, whereas the higher halogenated congeners (i.e. hepta-CBs) were mainly found in the inner and outer Blubber layers. The transfer ratios of both PBDEs and PCBs from inner Blubber to serum decreased with the number of chlorine and bromine atoms. In addition, the distribution of both types of compounds between serum and Blubber was strongly influenced by their lipophilic character (log Kow values), with more lipophilic compounds being less efficiently released from Blubber to serum.
Sara J Iverson - One of the best experts on this subject based on the ideXlab platform.
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Blubber fatty acid composition of bowhead whales balaena mysticetus implications for diet assessment and ecosystem monitoring
Journal of Experimental Marine Biology and Ecology, 2008Co-Authors: Suzanne M Budge, Sara J Iverson, Alan M Springer, G Sheffield, C RosaAbstract:Abstract Fatty acids (FA) have a diversity of structures that are transferred with little modification through food webs, making them valuable in assessing diets of animals that cannot be directly observed feeding. Before using FA to estimate diets, it is necessary to evaluate variation in FA signatures within and among individuals of a given species. To begin assessing diets and foraging of western Arctic bowhead whales ( Balaena mysticetus) , we examined the FA in Blubber of 64 bowheads taken in the spring and fall subsistence hunts in 1997–2002 at Barrow and Kaktovik, Alaska. We found no significant differences in FA characteristics of inner Blubber layers taken from either duplicate samples on the dorsal surface, or between dorsal and ventral sites. Significant differences were found in the FA composition between inner and outer layers of Blubber at the same body site. We also found age, season and year to have significant effects on FA composition; however, gender was not found to be significant. While the importance of the Beaufort Sea as a feeding ground of bowhead whales remains uncertain, our results indicate that adults and sub-adults foraged to some extent on different prey and that both age classes consumed copepods there in summer at sufficient levels to significantly alter their Blubber FA profiles. Both of these findings correspond with dietary conclusions reached from the analysis of stomach contents. Furthermore, we found compelling evidence that yearly variation in bowhead FA reflect changes in FA compositions of phytoplankton at the base of the food web, probably in response to climate variation. Variability in phytoplankton-derived FA in Blubber was correlated significantly with yearly mean values of the Pacific Decadal Oscillation. FA in bowhead whale Blubber, therefore, might be used to monitor effects of climate change on lower trophic levels and production processes in the western Arctic.
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determining Blubber fatty acid composition a comparison of in situ direct and traditional methods
Marine Mammal Science, 2004Co-Authors: Gregory W Thiemann, Suzanne M Budge, Sara J IversonAbstract:Fatty acids (FAs) are used to make inferences about the foraging behavior and diets of free-ranging marine mammals. However, several methods are currently available for determining the FA composition of Blubber and these methods may produce different results. We compared in situ direct transesterification methods, where a small amount of tissue is sampled, with more traditional methods involving prior lipid extraction of the entire sample of interest. Using gray seal (Halichoerus grypus) and beluga whale (Delphinapterus leucas) Blubber, we found that when the direct in situ method was used on a 2-mg sample of Blubber, the resulting FA profile differed significantly from that produced when traditional full-extraction methods were employed. Regardless of where the small spot sample was taken within the Blubber depth, it was not representative of the entire Blubber FA composition, as Blubber is non-homogeneous throughout its depth. We also modified the in situ direct method to allow analysis of the entire Blubber layer. Results of this full-layer direct method compared quite favorably with traditional extraction methods and may provide a reasonable alternative for analyses. Although application of our full-layer direct method will require further verification in certain marine mammal Blubber samples, we conclude that the large differences obtained when using the direct method are not a consequence of the chemical method itself. Rather, they arise from non-representative sampling of the Blubber FA composition.
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high concentrations of isovaleric acid in the fats of odontocetes variation and patterns of accumulation in Blubber vs stability in the melon
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2003Co-Authors: Sara J Iverson, Heather N Koopman, Andrew J ReadAbstract:Isovaleric acid (iso5:0) is an unusual fatty acid that is important for echolocation and hearing in acoustic tissues of some odontocetes, but its functional significance in Blubber is unknown. We examined patterns of accumulation of this compound in Blubber in 30 species of odontocetes (n=299). Iso5:0 concentrations in Blubber varied with phylogeny, ontogeny and body topography. Iso5:0 accumulated in greater quantities in superficial/outer Blubber than in deep/inner Blubber. In the outer Blubber of northern right whale and Hector's dolphins, iso5:0 accounted for one-third to one-half of all fatty acids. Total Blubber burden of iso5:0 in harbour porpoises represented up to 15 times the amount deposited in the melon. The composition of the melon does not change during starvation in harbour porpoises, supporting the hypothesis that lipids in melon are conserved for a specific function. Some odontocetes continually deposit iso5:0 in Blubber after levels in melon have reached asymptotic levels, suggesting independent control of iso5:0 synthesis and storage in these compartments. Dolphins and porpoises inhabiting cold waters possess higher concentrations of iso5:0 in their outer Blubber layers than species from warmer regions. We propose that this relationship represents an adaptive secondary role for iso5:0 in maintaining Blubber flexibility in cold environments.
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Fat transfer and energetics during lactation in the hooded seal: The roles of tissue lipoprotein lipase in milk fat secretion and pup Blubber deposition
Journal of Comparative Physiology - B Biochemical Systemic and Environmental Physiology, 1999Co-Authors: J. E. Mellish, W. D. Bowen, Sara J Iverson, Mike O. HammillAbstract:Hooded seals (Cystophora cristata) lactate for 3.6 days during which females simultaneously fast and transfer large amounts of energy to their pups through fat-rich milk. Pups grow rapidly, principally due to Blubber deposition. Lipoprotein lipase (LPL), the primary enzyme responsible for tissue uptake of triglyceride fatty acids, may strongly influence both maternal milk fat secretion and pup Blubber deposition. We measured the energetic costs of lactation (using hydrogen isotope dilution, (H2O)-H-3), milk composition, prolactin, and LPL activity (post-heparin plasma LPL [PH LPL], Blubber, mammary gland and milk; U) in six females. PH LPL and Blubber LPL were measured in their pups. Females depleted 216.3 MJ . day(-1) of body energy and fat accounted for 59% of maternal mass loss and 90% of postpartum body energy loss, but maternal body composition changed little. Maternal Blubber LPL was negligible (0.0-0.2 U), while mammary LPL was elevated (1.8-2.5 U) and was paralleled by changes in prolactin. Estimated total mammary LPL activity was high (up to 20,000 U . animal(-1)) effectively favoring the mammary gland for lipid uptake. Levels of total Blubber LPL in pups increased seven-fold over lactation. Pups with higher PH LPL at birth had greater relative growth rates (P = 0.025). Pups with greater Blubber stores and total Blubber LPL activity had elevated rates of fat deposition (P = 0.035).
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stratification and age related differences in Blubber fatty acids of the male harbour porpoise phocoena phocoena
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 1996Co-Authors: H N Koopman, Sara J Iverson, D E GaskinAbstract:Fatty acid composition of Blubber was determined at four body sites of 19 male harbour porpoises. A total of 65 fatty acids were quantified in each sample. The array of fatty acids contained in harbour porpoise Blubber was similar to those found in other marine mammals. While chemical composition of total Blubber was uniform over the body, with the exception of the caudal peduncle, vertical stratification was evident between the deep (inner) and superficial (outer) Blubber layers. Fatty acids with chain lengths shorter than 18 carbons were present in significantly greater amounts in the outer Blubber layer, while the longer-chain unsaturated fatty acids were more prevalent in the inner layer. This distribution suggests that the inner Blubber layer is more active metabolically than the outer layer in terms of lipid deposition and mobilization. The degree of stratification between the two layers appears to increase with age, indicating a predictable turnover in the Blubber layer of male porpoises. Harbour porpoise Blubber contained high levels (2–27%) of isovaleric acid in the outer Blubber layer, and these levels were positively correlated with age.
Daniel P Costa - One of the best experts on this subject based on the ideXlab platform.
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Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants
Science of The Total Environment, 2015Co-Authors: Sarah H Peterson, Daniel E Crocker, Cathy Debier, Alin C Dirtu, Govindan Malarvannan, Adrian Covaci, Lisa K Schwarz, Michael G. Peterson, Daniel P CostaAbstract:As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in Blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately sevenmonthlong foraging trip.Formales,we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females,we calculated Blubber burdens for all compounds. The highest POP concentrations in males and females were found for ΣDDTs andΣPCBs. In Blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females,ΣDDT andΣPBDEs were highly correlated in Blubber and serum.While ΣPCBs were highly correlatedwithΣDDTs andΣPBDEs in Blubber and serum formales,ΣPCBs showed weaker correlationswith both compounds in females. As females gainedmasswhile foraging, concentrations of nearly all POPs in inner and outer Blubber significantly decreased; however, the absolute burden in Blubber significantly increased, indicating ingestion of contaminantswhile foraging. Additionally,we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences inΣDDTs,ΣPBDEs, MeO-BDE 47, as well as the ratio ofΣDDTs toΣPCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations ofΣDDTs and ΣPBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in 13C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.
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comparisons and uncertainty in fat and adipose tissue estimation techniques the northern elephant seal as a case study
PLOS ONE, 2015Co-Authors: Lisa K Schwarz, Daniel P Costa, Stella Villegasamtmann, Roxanne S Beltran, Chandra Goetsch, Luis A Huckstadt, Jennifer L Maresh, Sarah H PetersonAbstract:Fat mass and body condition are important metrics in bioenergetics and physiological studies. They can also link foraging success with demographic rates, making them key components of models that predict population-level outcomes of environmental change. Therefore, it is important to incorporate uncertainty in physiological indicators if results will lead to species management decisions. Maternal fat mass in elephant seals (Mirounga spp) can predict reproductive rate and pup survival, but no one has quantified or identified the sources of uncertainty for the two fat mass estimation techniques (labeled-water and truncated cones). The current cones method can provide estimates of proportion adipose tissue in adult females and proportion fat of juveniles in northern elephant seals (M. angustirostris) comparable to labeled-water methods, but it does not work for all cases or species. We reviewed components and assumptions of the technique via measurements of seven early-molt and seven late-molt adult females. We show that seals are elliptical on land, rather than the assumed circular shape, and skin may account for a high proportion of what is often defined as Blubber. Also, Blubber extends past the neck-to-pelvis region, and comparisons of new and old ultrasound instrumentation indicate previous measurements of sculp thickness may be biased low. Accounting for such differences, and incorporating new measurements of Blubber density and proportion of fat in Blubber, we propose a modified cones method that can isolate Blubber from non-Blubber adipose tissue and separate fat into skin, Blubber, and core compartments. Lastly, we found that adipose tissue and fat estimates using tritiated water may be biased high during the early molt. Both the tritiated water and modified cones methods had high, but reducible, uncertainty. The improved cones method for estimating body condition allows for more accurate quantification of the various tissue masses and may also be transferrable to other species.
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mobilisation of lipophilic pollutants from Blubber in northern elephant seal pups mirounga angustirostris during the post weaning fast
Environmental Research, 2014Co-Authors: Caroline Louis, Daniel E Crocker, Alin C Dirtu, Marie Stas, Yves Guiot, Govindan Malarvannan, Daniel P Costa, Adrian Covaci, Cathy DebierAbstract:Northern elephant seals (NES) (Mirounga angustirostris) from the Ano Nuevo State Reserve (CA, USA) were longitudinally sampled during the post-weaning fast in order to study the mobilisation and redistribution of various classes of persistent organic pollutants (POPs), such as polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB) between Blubber and blood. Inner and outer Blubber layers were analysed separately. Organohalogenated compounds were detected in all Blubber samples in the decreasing order of their concentrations: p,p′-DDE>PCBs⪢HCB>PBDEs. The concentrations of all studied compounds were homogeneously distributed in the Blubber layer at early fast, since the concentrations of POPs were statistically not different in the inner and outer layers. With the progression of the fast, the concentrations of PBDEs, PCBs and p,p′-DDE increased more sharply in inner Blubber than in outer Blubber. As a result, their levels became significantly higher in inner Blubber as compared to outer Blubber at late fast. The rise of pollutant concentrations in Blubber might result from a less efficient mobilisation than triglycerides and/or a reuptake by adipocytes of some of the pollutants released into the circulation. The mobilisation of pollutants from Blubber was higher at late fast. An increase of pollutant concentrations was observed in serum between early and late fast. Lower halogenated congeners (i.e. tetra-CBs) were present in higher proportions in serum, whereas the higher halogenated congeners (i.e. hepta-CBs) were mainly found in the inner and outer Blubber layers. The transfer ratios of both PBDEs and PCBs from inner Blubber to serum decreased with the number of chlorine and bromine atoms. In addition, the distribution of both types of compounds between serum and Blubber was strongly influenced by their lipophilic character (log Kow values), with more lipophilic compounds being less efficiently released from Blubber to serum.
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morphological and thermal properties of mammalian insulation the evolutionary transition to Blubber in pinnipeds
Biological Journal of The Linnean Society, 2012Co-Authors: Heather E M Liwanag, Daniel P Costa, Annalisa Berta, Suzanne M Budge, Terrie M WilliamsAbstract:Carnivora includes three independent evolutionary transitions to the marine environment: pinnipeds (seals, sea lions, and walruses), sea otters, and polar bears. Among these, only the pinnipeds have retained two forms of insulation, an external fur layer and an internal Blubber layer for keeping warm in water. In this study we investigated key factors associated with the transition to the use of Blubber, by comparing Blubber characteristics among the pinnipeds. Characteristics included gross morphology (Blubber thickness), fat composition (fatty acid profiles, percentage lipid, and water), and thermal conductivity. Sea lions, phocids, and walrus, which have lower fur densities than fur seals, have thicker Blubber layers than fur seals (P < 0.001). Comparisons of lipid content, water content, and fatty acid composition indicated significant differences in the composition of the inner and outer regions of the Blubber between groups (P < 0.001), consistent with the hypothesis that phocids and sea lions utilize the outer layer of their Blubber primarily for thermal insulation, and the inner layer for energy storage. Fur seals, by contrast, rely more on their fur for thermal insulation, and utilize their Blubber layer primarily for energy storage. Comparing across carnivore species, differences in total insulation (fur and/or Blubber) are influenced substantially by body size and habitat, and to a lesser extent by latitudinal climate. Overall, these results indicate consistent evolutionary trends in the transition to Blubber and evidence for convergent evolution of thermal traits across lineages. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.
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Morphological and thermal properties of mammalian insulation: the evolutionary transition to Blubber in pinnipeds
Biological Journal of The Linnean Society, 2012Co-Authors: Heather E M Liwanag, Daniel P Costa, Annalisa Berta, Suzanne M Budge, Terrie M WilliamsAbstract:Carnivora includes three independent evolutionary transitions to the marine environment: pinnipeds (seals, sea lions, and walruses), sea otters, and polar bears. Among these, only the pinnipeds have retained two forms of insulation, an external fur layer and an internal Blubber layer for keeping warm in water. In this study we investigated key factors associated with the transition to the use of Blubber, by comparing Blubber characteristics among the pinnipeds. Characteristics included gross morphology (Blubber thickness), fat composition (fatty acid profiles, percentage lipid, and water), and thermal conductivity. Sea lions, phocids, and walrus, which have lower fur densities than fur seals, have thicker Blubber layers than fur seals (P
