Seal Blubber Research Articles

Factors affecting the degree of vertical stratification of fatty acids in grey seal blubber

The biochemistry of marine mammal blubber differs vertically from skin to muscle, which forms a challenge for using fatty acids (FAs) from differently sampled blubber as a proxy for dietary studies required for ecosystem-based management of coastal resources. In the blubber of some phocid seal individuals, the vertical stratification of several FAs is pronounced whereas in others the FAs distribute almost evenly through the blubber column. Using gas chromatography, we analysed the blubber vertical FA profiles of 30 adult male grey seals from the Baltic Sea, and examined which factors induced the largest vertical change of FA composition detected at the depth of 15–18 mm (outer and middle blubber boundaries). It was revealed that the degree of this compositional shift did not depend on the blubber thickness. Seal age only affected the vertical distribution of the FAs 16:0 and 16:1n-7. However, the outer blubber ratio of ∆9-desaturated monounsaturated FAs (MUFAs) to their saturated FA (SFA) precursors was not increased by grey seal age, contrasting earlier findings for ringed seals. A major determinant of the degree of FA stratification between the outer and middle blubber was the mismatch between the individually varying FA composition of the innermost blubber, regarded to reflect the dietary FA supply the most, and the uniform FA composition of endogenously regulated MUFA-rich outer blubber. Thus, discarding a fixed-depth layer of the grey seal outermost blubber, which we here show to span 0–18 mm from skin and which to a lesser extent reflects the diet of the individual, may in the case of small pinnipeds improve the sensitivity of the FA analysis in assessing spatial, temporal and individual dietary differences. When studying the outer blubber samples using only the diet-derived PUFA variables (SFAs and MUFAs omitted), the sensitivity of the analysis was better than when using this sample type with all main FA variables included.

Bioaccumulation and biomagnification of perfluoroalkyl acids and precursors in East Greenland polar bears and their ringed seal prey

The bioaccumulation and biomagnification of 22 major perfluoroalkyl substances (PFAS) were investigated in tissues of polar bears (Ursus maritimus) and their major prey species, the ringed seal (Pusa hispida), from the Scoresby Sound region of East Greenland. In polar bear liver the mean Σ4PFSA (perfluoroalkyl sulfonic acid) concentration (C4, C6, C8 and C10) was 2611 ± 202 ng/g wet weight (ww; 99% perfluorooctane sulfonate (PFOS)) and two orders of magnitude higher than the 20 ± 3 ng/g ww (89% PFOS) concentration in fat. The mean Σ4PFSAs in seal liver was 111 ± 5 ng/g ww (98% PFOS) and three orders of magnitude higher relative to the 0.05 ± 0.01 ng/g ww concentration in blubber (100% perfluorohexane sulfonate). Perfluoro-1-octane sulfonamide (FOSA) was quantifiable in bear (mean 10 ± 1.4 ng/g ww) and seal (mean 0.6 ± 0.1 ng/g ww) liver but not in fat or blubber. The mean Σ13PFCAs (C4–C18; perfluoroalkyl carboxylic acids) in bear liver (924 ± 71 ng/g ww) was much greater than in seal liver (74 ± 6 ng/g ww). In bear fat and seal blubber, the mean Σ13PFCAs were 15 ± 1.9 and 0.9 ± 0.1 ng/g ww, respectively. Longer chain C11 to C14 PFCAs dominated in bear fat and seal blubber (60–80% of Σ13PFCA), whereas shorter-chain C9 to C11 PFCAs dominated in the liver (85–90% of Σ13PFCA). Biomagnification factors (BMFs) were orders of magnitude greater for PFHxS and C9 to C13 PFCAs when based on bear liver to seal blubber rather than bear liver to seal liver, and PFCA (C9 to C13) BMFs decreased with increasing chain length. Seal blubber to bear liver BMFs better reflects the dietary exposure relationship of PFAS between bears and seals.

A concept for studying the transformation reaction of hexachlorocyclohexanes in food webs using multi-element compound-specific isotope analysis

An analytical concept using stable isotope fractionation for analyzing persistent organic pollutants (POPs) in food webs was developed and tested. We have evaluated methods for the extraction and clean-up of hexachlorocyclohexane isomers (HCHs) as the model compounds of POPs from water, soil, plant, milk, fish oil and pork liver in order to study the reactive transport processes of HCHs in food webs using multi-element compound-specific isotope analysis (CSIA). The extraction and clean-up methods were evaluated for recovery efficiency and isotope effects. The precision and accuracy for carbon, hydrogen and chlorine isotope analysis were within the analytical precision of ±0.5‰, ±5‰ and ±0.3‰, respectively. The method was applied for stable isotope analysis of HCHs in possible food webs from soil to plants, and to animals. Isotope compositions of HCHs in cow/buffalo milk and dung, wild animal livers and seal blubber were obtained and compared to the sources of HCHs. The magnitude of isotope enrichment demonstrated the potential of CSIA for analyzing reactive transport processes of HCHs in the food web. The concept using multi-element stable isotope analysis can be applied for source identification, characterization of degradation mechanisms, and particularly contaminant accumulation in the food web, which demonstrates the potential in new scientific areas for CSIA.

Traditional Diet and Environmental Contaminants in Coastal Chukotka II: Legacy POPs.

The article is the second in the series of four that present the results of a study on environmental contaminants in coastal Chukotka, conducted in the context of a multi-disciplinary investigation of indigenous foodways in the region. The article presents the results of the analysis of legacy Persistent Organic Pollutants (POPs) found in the samples of locally harvested food and indoor matters, collected in 2016 in coastal Chukotka. Temporal trends and circumpolar comparisons of POPs in food have been carried out. Estimated daily intakes (EDIs) of POPs by local food consumption were calculated based on the food intake frequencies (questionnaire data). Concentrations of the studied legacy POPs in marine mammal blubber were relatively high (up to 100–200 µg/kg ww) but not exceeding the allowable limits. Gray whale blubber and whale mantak were the most contaminated foods, followed by the ringed, spotted and bearded seal blubber, then by walrus blubber and fermented walrus (deboned walrus parts aged in subterranean pits, typically over a period of 6 months). At the backdrop of general decrease or invariability (compared to the previous coastal Chukotka study 15 years ago) of the majority of POPs, an increasing tendency of HCB, mainly in marine mammals, were noted. Legacy POPs in marine mammals sampled in Chukotka were generally much lower than in those sampled in Alaska and northern Canada. We suggest that the Alaska Coastal Current from the Bering Sea plays a major role in this phenomenon. Analyses of the additional sources of in-home food contamination (home-brewed alcohol, domestic insecticides) have revealed relatively high levels of HCHs, DDTs and PCBs, which still represent a share of dietary exposure of local people to POPs.

Trends of persistent organic pollutants in ringed seals (Phoca hispida) from the Canadian Arctic

Ringed seals (Phoca hispida) have been used as bioindicator species of environmental contamination in Canada since the 1970s. In the present study, seals were harvested during subsistence hunts in four regions of the Canadian Arctic: Beaufort Sea, Arctic Archipelago, Hudson Bay, and coastal Labrador. An extensive suite of persistent organic pollutants (POPs) was determined in seal blubber collected for multiple years between 1972 and 2016. Results from this long-term study indicate geographical differences in the contaminant concentrations in seals and the significant general decrease of most POPs, including polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and related compounds, chlordanes (CHL), and hexachlorocyclohexanes (HCH) over time in ringed seals. The highest decrease rates (up to −9.1%/year for α-HCH) were found in seals from the Hudson Bay region where all chemicals investigated have significantly decreased since 1986. Significant increases in concentrations of hexachlorobenzene (HCB) in seals from Labrador and β-HCH in Sachs Harbour, NT and Arctic Archipelago were observed. Site-specific and contaminant-specific associations between climate pattern (i.e., Arctic Oscillation, North Atlantic Oscillation, and Pacific/North American pattern) and mean ice-coverage (total, first-year ice, and old-ice) were found at sites with the longest time trend data (i.e., Arviat, Sachs Harbour/Ulukhaktok and Resolute Bay). Overall, results suggest that North American and international regulations have led to the long-term reduction of most POPs in Canadian Arctic ringed seals by reducing emissions from primary sources. However, other sources of legacy compounds (e.g., environmental reservoirs) as well changes in food web composition and structure in relation to climate changes could also be influencing the very slow rates of decline, or stable levels, of contaminants found in seals at some sites. Further work is warranted to discern between co-variation of climate changes and contaminant concentrations and cause-and-effect relationships.

Two step-production of acylglycerols containing a high proportion of docosapentaenoic acid from marine omega-3 oil and their oxidative stability

The objective of this study was to concentrate polyunsaturated fatty acid (PUFA) from seal blubber oil in an innovative manner to produce a high content of docosapentaenoic acid (DPA) in the resultant product. It also aimed at investigating the use of lipases as catalysts for synthesizing acylglycerols from glycerol and polyunsaturated fatty acid concentrates. Additionally, study of the oxidative stability of acylglycerols synthesized by lipases was intended. A two-stage urea complexation process was used to concentrate PUFA from seal blubber oil, giving rise to a DPA content of up to 24.0% in the product. Enzymatic synthesis of acyglycerols directly from glycerol and fatty acid concentrate was studied. Three lipases were used as biocatalysts for esterification. Lipase SP435 from Candida antarctica showed the highest activity for esterification. Effects of reaction parameters, namely temperature, time course and mole ratio of glycerol to fatty acid were followed with all three lipases. The optimal reaction time was 24 hr at 30 °C at a mole ratio of glycerol to fatty acid of 14:1. The maximum degree of acylglycerol synthesis was > 90%. The effect of time course and mole ratio of glycerol to fatty acid on acylglycerols distribution was also determined. The oxidative stability of different samples under Schaal-oven conditions at 60 °C showed that the oxidative stability of acylglycerols was better than that of the corresponding fatty acid esters.

Characterization of brominated, chlorinated, and phosphate flame retardants in San Francisco Bay, an urban estuary

Flame retardant chemical additives are incorporated into consumer goods to meet flammability standards, and many have been detected in environmental matrices. A uniquely wide-ranging characterization of flame retardants was conducted, including polybrominated diphenyl ethers (PBDEs) and 52 additional brominated, chlorinated, or phosphate analytes, in water, sediment, bivalves, and harbor seal blubber of San Francisco Bay, a highly urbanized estuary once considered a hot spot for PBDE contamination. Among brominated flame retardants, PBDEs remained the dominant contaminants in all matrices, though declines have been observed over the last decade following their phase-out. Hexabromocyclododecane (HBCD) and other hydrophobic, brominated flame retardants were commonly detected at lower levels than PBDEs in sediment and tissue matrices. Dechlorane Plus (DP) and related chlorinated compounds were also detected at lower levels or not at all across all matrices. In contrast, phosphate flame retardants were widely detected in Bay water samples, with highest median concentrations in the order TCPP > TPhP > TBEP > TDCPP > TCEP. Concentrations in Bay water were often higher than in other estuarine and marine environments. Phosphate flame retardants were also widely detected in sediment, in the order TEHP > TCrP > TPhP > TDCPP > TBEP. Several were present in bivalves, with levels of TDCPP comparable to PBDEs. Only four phosphate flame retardants were detected in harbor seal blubber: TCPP, TDCPP, TCEP, and TPhP. Periodic, multi-matrix screening is recommended to track contaminant trends impacted by changes to flammability standards and manufacturing practices, with a particular focus on contaminants like TDCPP and TPhP that were found at levels comparable to thresholds for aquatic toxicity.

Exposure to Perfluoroalkyl Substances and Polybrominated Diphenyl Ethers from Traditionally Harvested Food Animals on St. Lawrence Island, Alaska

The Arctic serves as a hemispheric sink for persistent organic pollutants(POPs). Indigenous arctic populations are exposed to POPs through traditional harvest of food animals, including marine mammals. This study quantified 13 perfluoroalkyl substances (PFAS) and 40 polybrominated diphenyl ethers in traditional food animals harvested by residents of St. Lawrence Island, Alaska. Of 13 measured PFAS, 9 were detectable in any sample. Overall PFAS concentrations were highest in seal tissue. In seal tissue samples, Perfluoropentanoic acid (PFPeA) was the most commonly detected PFAS, and was present at the highest mean concentration of any PFAS (15.4 ng/g ww). PFPeA was also the most commonly detected PFAS and was present the highest maximum concentration (24.8 ng/g in seal muscle). Analysis of heart, liver, kidney and intestine samples from a single juvenile seal suggest that PFAS may preferentially partition into organs. Both total concentrations of PFAS and the number of detectable compounds were higher in these organ meats. Polybrominated diphenyl ethers (PBDEs) were detected in 100% of traditional foods samples. BDE-47, 99, 100 and 209 tended to make up a large percentage of overall PBDE concentrations. Seals had the highest median concentrations compared to other species. BDE-47 made up the majority of overall PBDE concentrations in seal samples. The median total PBDE concentration in seal blubber from this study (2,511 pg/g ww) was lower than the concentration reported in harbor seals collected in Alaska in 2000-2002 (14,600 pg/g ww). This is consistent with the overall decreasing trends of PBDEs in the Arctic.

Accumulation of PBDEs in stranded harp (Pagophilus groenlandicus) and hooded seals (Cystophora cristata) from the Northeastern United States

Polybrominated diphenyl ethers (PBDEs) are highly lipophilic components of brominated flame retardants that are environmentally persistent and bioaccumulate. PBDEs are taken up from the gastrointestinal tract and accumulate mainly in fat depots and liver tissues. Seal species inhabiting Arctic and sub-Arctic regions can have upwards of 30% of their body mass composed of blubber. When those blubber stores are mobilized for energy, stored toxicants are also released into circulation. Most studies reporting accumulation of PBDEs in seals have focused on harbor and grey seals with few examining harp and hooded seals. In this study, PBDEs concentrations were analyzed in seal blubber from 21 stranded harp and 9 stranded hooded seals sampled along the northeast coast of the U.S. (1999–2010). A PBDE congener profile was determined for each individual. The results show that both species of seals are accumulating PBDEs with BDE-47 being the dominant congener. Mean ƩPBDE concentrations in harp seals were 70.55 ± 33.59 ng/g ww and for hooded seals 94.28 ± 42.65 ng/g ww. The results of this study are consistent with previous studies reporting a decrease in bioaccumulation with an increase in bromination. For both species, BDE-47 represented the highest percentage of the ƩPBDEs, composing over 50% of the ƩPBDEs in harp seals. When compared to stranding condition code, animals found alive had overall higher PBDE concentrations than those found in a state of moderate decomposition. This difference could be due to decreased blubber levels in the decomposed animals or potential degradation of the compounds in the blubber. Almost all seals used in this study were yearlings which is the most likely age class to strand. Yearling seals are at a crucial stage of development, especially of their immune system, which can be impacted by high levels of contaminants like PBDEs and increase the susceptibility to disease.

A sample preparation workflow for adipose tissue shotgun proteomics and proteogenomics.

ABSTRACTAnimals with large adipose stores, such as marine mammals, may provide insights into the evolution and function of this multifunctional tissue in health and disease. In the absence of sequenced genomes, molecular information can be rapidly obtained by proteomics and transcriptomics, but their application to adipose tissue is hindered by low nucleic acid and protein yields. We sequenced and compared proteomes isolated from the blubber of four elephant seals using phenol and guanidine thiocyanate (Qiazol) or detergent (sodium deoxycholate) buffer. Qiazol recovered more subcellular proteins such as metabolic enzymes, in addition to extracting RNA, facilitating proteogenomic analyses of small lipid-rich tissue biopsies. We also compared proteomics data analysis platforms and found that de novo peptide sequencing improved protein identification sensitivity compared to database search alone. We report sample preparation and data analysis workflows for proteogenomics and a proteome of elephant seal blubber containing 2678 proteins, including many of interest for further functional studies.This article has an associated First Person interview with the first author of the paper.

Oxidative stability of marine oils as affected by added wheat germ oil

ABSTRACTMarine oils, such as seal blubber and menhaden oils, offer a wide range of health benefits and play a critical role in many functions in the human body. These oils are highly vulnerable to oxidation due to their high content of polyunsaturated fatty acids. In this study, the stabilizing effect of blending of seal blubber and menhaden oils with antioxidant rich-wheat germ oil was investigated. Conjugated dienes and thiobarbituric acid reactive substances were used as indicators of oxidative stability. Fatty acid composition of the original oils and blends was determined using gas chromatography, while tocopherol content was assessed using high-performance liquid chromatography-mass spectrometry. The results showed that blending with wheat germ oil increased the tocopherol content of seal blubber and menhaden oils. The oxidative stability of blended seal blubber and menhaden oils was improved, and higher oxidative stability was positively correlated with higher percentage of added wheat germ oil.

Utility of fur as a biomarker for persistent organic pollutants in Australian fur seals (Arctocephalus pusillus doriferus)

Persistent Organic Pollutants (POPs) can cause toxic effects in many species which include endocrine dysfunction, immunotoxicity, developmental defects and neoplasia. Species dominating the upper trophic level are vulnerable to these effects due to bioaccumulation. In Bass Strait, the Australian fur seal (Arctocephalus pusillus doriferus) is an important top order predator and sentinel species for ecosystem health. An alopecia syndrome is seen at high prevalence in juvenile, female Australian fur seals at Lady Julia Percy Island, Victoria, Australia. Previous investigations suggest causality could be due to an endocrine-like toxicant. The alopecia syndrome has significance for thermoregulation and is a likely risk factor for mortality. Fur collected from case (alopecic) and control (unaffected) seals sampled at Lady Julia Percy Island were analysed for POPs. To investigate the utility of fur for monitoring POPs concentrations in pinnipeds, a comparison of POPs concentrations in the fur and blubber of Australian fur seals stranded along the Victorian coast was undertaken.The concentration of selected POPs including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), polybrominated diphenyl ethers (PBDEs) and perfluorooctane sulfonate/perfluorooctanoic acid (PFOS/PFOA) were determined in fur using either High Resolution Gas Chromatography-Mass Spectrometry or Liquid Chromatography-Mass Spectrometry. Results indicate detectable, and in some individuals, elevated levels of dl-PCBs, PCDD/Fs and PBDEs in juvenile fur seals sampled on Lady Julia Percy Island, with significantly higher levels of dl-PCBs in case compared to control seals. Elevated levels of dl-PCBs and PCDD/Fs were found in blubber samples collected from stranded fur seals with significant correlations between blubber and fur concentrations seen, particularly for dl-PCBs. This study discusses the significance of POPs concentrations in relation to the causality of an alopecia syndrome in the Australian fur seal, and assesses the utility of fur as a non-invasive biomarker to monitor POPs exposure in this sentinel species.

Endosulfan, Short-Chain Chlorinated Paraffins (SCCPs) and Octachlorostyrene in Wildlife from Greenland: Levels, Trends and Methodological Challenges.

Besides globally banned "legacy" persistent organic pollutants, other compounds might be present in Arctic wildlife, for which regulation was introduced recently (the insecticide endosulfan), is considered (short-chain chlorinated paraffins, SCCPs) or does not exist (octachlorostyrene, OCS, a byproduct of manufacturing and combustion processes involving chlorine). The purpose of this study was to analyze the time trend of endosulfan (1986-2012) in ringed seals and to address the levels of SCCPs and OCS in wildlife species from Greenland (black guillemot, glaucous gull, ringed seal, polar bear), while taking a critical standpoint to analytical methods typically applied. The metabolite endosulfan sulfate was the only endosulfan compound consistently above detection limits, with a median concentration of 0.23ng/g lipid weight (lw) and a significant annual decrease of -5.6%. The low-resolution mass spectrometry (LRMS) method appeared accurate and sufficiently precise; however, the gel permeation chromatography had to balance lipid removal and analyte loss. SCCPs and OCS were present in all samples. OCS median concentrations were between 2.8 (ringed seal blubber) and 29 (glaucous gull liver) ng/g lw, determined by a straightforward dual column electron capture detection method. SCCPs were analyzed by LRMS, following removal of potential interferences, and had median concentrations of several 100ng/g wet weight. While the method showed good precision and recovery rates as well as acceptable accuracy in control samples, the Greenland samples had high concentrations in an Arctic context, possibly indicating limited selectivity of the LRMS method.

Blubber fatty acid composition and stratification in the crabeater seal, Lobodon carcinophaga

The study of blubber fatty acids (FAs) has attracted increasing scientific interest due mainly to its potential use as trophic markers. This is possible because most FAs are transferred unmodified from the prey to the blubber of the predator. Additionally, FAs have also been used to understand other aspects of the biology of marine mammals, including thermoregulation and reproductive stage. The aim of this study is to determine the FA composition of the blubber of the crabeater seal, which has not been reported before, and identify stratification of FAs across the blubber layer. Seals were captured in the western Antarctic Peninsula during the austral summer of 2015 and a whole blubber core (down to the muscle layer) sample was collected. The blubber core was sub-sectioned into inner and outer layers and analysed for FAs. The FA composition of crabeater seals was similar to other marine mammals, with high proportions of 18:1ω9, 16:1ω7, and 16:0. These FAs are endogenous, that is, they can be readily synthesised by mammals. However, the high proportions of 22:6ω3 and 20:5ω3 are unusual among other marine mammals. These FAs are potentially reflecting the diet of crabeater seals, as they have a dietary origin and are known to be abundant in krill, the main prey item of this predator. Inner and outer layers were significantly different indicating a stratification of blubber FAs. The pattern of stratification is ubiquitous in marine mammals, with monounsaturated FAs increasing towards the outer layer, and saturated and polyunsaturated FAs increasing towards the inner layer. This difference between inner and outer layers may indicate that they have different metabolic roles. Because most dietary FAs were more abundant in the inner layer, this is likely to be the section where the dietary process takes place. The higher proportions of monounsaturated FAs in the outer layer suggest that this section of the blubber plays a more functional role, probably related to thermoregulation, as these FAs prevent rigidity and improve fluidity, which is particularly important in cold environments.

Blubber transcriptome response to acute stress axis activation involves transient changes in adipogenesis and lipolysis in a fasting-adapted marine mammal

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.

From Sediment to Top Predators: Broad Exposure of Polyhalogenated Carbazoles in San Francisco Bay (U.S.A.).

The present study provides the first comprehensive investigation of polyhalogenated carbazoles (PHCZs) contamination in an aquatic ecosystem. PHCZs have been found in soil and aquatic sediment from several different regions, but knowledge of their bioaccumulation and trophodynamics is extremely scarce. This work investigated a suite of 11 PHCZ congeners in San Francisco Bay (United States) sediment and organisms, including bivalves (n = 6 composites), sport fish (n = 12 composites), harbor seal blubber (n = 18), and bird eggs (n = 8 composites). The most detectable congeners included 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), 1,3,6-tribromocarbazole (136-BCZ), 1,3,6,8-tetrabromocarbazole (1368-BCZ), and 1,8-dibromo-3,6-dichlorocarbazole (18-B-36-CCZ). The median concentrations of ΣPHCZs were 9.3 ng/g dry weight in sediment and ranged from 33.7 to 164 ng/g lipid weight in various species. Biomagnification was observed from fish to harbor seal and was mainly driven by chlorinated carbazoles, particularly 36-CCZ. Congener compositions of PHCZs differed among species, suggesting that individual congeners may be subject to different bioaccumulation or metabolism in species occupying various trophic levels in the studied aquatic system. Toxic equivalent (TEQ) values of PHCZs were determined on the basis of their relative effect potencies (REP) compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The median TEQ was 1.2 pg TEQ/g dry weight in sediment and 4.8-19.5 pg TEQ/g lipid weight in biological tissues. Our study demonstrated the broad exposure of PHCZs in San Francisco Bay and their characteristics of bioaccumulation and biomagnification along with dioxin-like effects. These findings raise the need for additional research to better elucidate their sources, environmental behavior, and fate in global environments.

De novo assembly of the ringed seal (Pusa hispida) blubber transcriptome: A tool that enables identification of molecular health indicators associated with PCB exposure

The ringed seal, Pusa hispida, is a keystone species in the Arctic marine ecosystem, and is proving a useful marine mammal for linking polychlorinated biphenyl (PCB) exposure to toxic injury. We report here the first de novo assembled transcriptome for the ringed seal (342,863 transcripts, of which 53% were annotated), which we then applied to a population of ringed seals exposed to a local PCB source in Arctic Labrador, Canada. We found an indication of energy metabolism imbalance in local ringed seals (n=4), and identified five significant gene transcript targets: plasminogen receptor (Plg-R(KT)), solute carrier family 25 member 43 receptor (Slc25a43), ankyrin repeat domain-containing protein 26-like receptor (Ankrd26), HIS30 (not yet annotated) and HIS16 (not yet annotated) that may represent indicators of PCB exposure and effects in marine mammals. The abundance profiles of these five gene targets were validated in blubber samples collected from 43 ringed seals using a qPCR assay. The mRNA transcript levels for all five gene targets, (Plg-R(KT), r2=0.43), (Slc25a43, r2=0.51), (Ankrd26, r2=0.43), (HIS30, r2=0.39) and (HIS16, r2=0.31) correlated with increasing levels of blubber PCBs. Results from the present study contribute to our understanding of PCB associated effects in marine mammals, and provide new tools for future molecular and toxicology work in pinnipeds.

Spatial and temporal trends of alternative flame retardants and polybrominated diphenyl ethers in ringed seals (Phoca hispida) across the Canadian Arctic

Concentrations of alternative flame retardants and polybrominated diphenyl ethers (PBDEs) were analyzed in ringed seal (Phoca hispida) blubber collected across the Canadian Arctic during subsistence hunts between 1998 and 2013. More than 80% of sampled animals were females and juvenile males. The highest mean ΣPBDE concentrations (sum of 13 congeners) were found in seals from Nain (Nunatsiavut) as well as Inukjuaq and Arviat (Hudson Bay) and the lowest mean levels were found in seals from Lancaster Sound. BDE-47 and -99 were the predominant PBDE congeners quantified in ringed seals. The most frequently detected non-PBDE flame retardants were polybrominated biphenyl 101 (BB-101, 57% of samples analyzed for this chemical), hexabromocyclododecane (HBCDD; 38%), hexabromobenzene (HBB, 30%), and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTeBB, 23%). The relative trophic position of seals, estimated using stable isotopes, did not vary over time and did not influence flame retardant blubber concentrations. The relative carbon source increased over time at Arviat and Resolute Bay and weak relationships were observed with ΣPBDEs in blubber of seals. ΣPBDEs increased significantly from 1998 to 2008 in ringed seals from East Baffin and subsequently decreased in recent years. PBDE levels at other sites fluctuated slightly over time. HBCDD concentrations increased at several sites over the past decade. The presence of flame retardants in ringed seals suggests their persistence and their continuous inputs in the Canadian Arctic environment. Monitoring and research on the effects of these contaminants in seals are warranted given the importance of this species in Arctic marine food webs and for local communities.

Of Penguins, Pinnipeds, and Poisons: Anesthesia on Elephant Island.

Although Ernest Shackleton's Endurance Antarctic expedition of 1914 to 1916 is a famous epic of survival, the medical achievements of the two expedition doctors have received little formal examination. Marooned on Elephant Island after the expedition ship sank, Drs. Macklin and McIlroy administered a chloroform anesthetic to crew member Perce Blackborow to amputate his frostbitten toes. As the saturated vapor pressure of chloroform at 0°C is 71.5 mmHg and the minimum alveolar concentration is 0.5% of sea-level atmospheric pressure (3.8 mmHg), it would have been feasible to induce anesthesia at a low temperature. However, given the potentially lethal hazards of a light chloroform anesthetic, an adequate and constant depth of anesthesia was essential. The pharmacokinetics of the volatile anesthetic, administered via the open-drop technique in the frigid environment, would have been unfamiliar to the occasional anesthetist. To facilitate vaporization of the chloroform, the team burned penguin skins and seal blubber under overturned lifeboats to increase the ambient temperature from -0.5° to 26.6°C. Chloroform degrades with heat to chlorine and phosgene, but buildup of these poisonous gases did not occur due to venting of the confined space by the stove chimney. The anesthetic went well, and the patient-and all the ship's crew-survived to return home.

Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea.

Dramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering-Chukchi continental shelf have occurred in this century, raising a pressing ecological question: Do such environmental changes alter marine production processes linking primary producers to upper trophic-level predators? We examined this question by comparing the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ¹³CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as "ice seals," sampled during an anomalously warm, low sea ice period in 2002-2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007-2010. δ¹³C(FA) values, used to estimate the contribution to seals of carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), indicated that during the cold period, sympagic production accounted for 62-80% of the FA in the blubber of bearded seals, 51-62% in spotted seals, and 21-60% in ringed seals. Moreover, the δ¹³CFA values of bearded seals indicated a greater incorporation of sympagic FAs during the cold period than the warm period. This result provides the first empirical evidence of an ecosystem-scale effect of a putative change in sympagic production in the Western Arctic. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. Despite interannual variability, the FA composition of ringed and bearded seals showed little evidence of differences in diet between the warm and cold periods. The findings that sympagic production contributes significantly to food webs supporting ice seals, and that the contribution apparently is less in warm years with low sea ice, raise an important concern: Will the projected warming and continuing loss of seasonal sea ice in the Arctic, and the associated decline of organic matter input from sympagic production, be compensated for by pelagic production to satisfy both pelagic and benthic carbon and energy needs?