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Blubber taken from ringed seals (Pusa hispida) during a subsistence hunt at Ulukhaktok, NT (formerly Holman, NWT) at intervals between 2002 and 2015 was analysed for polybrominated diphenyl ether (PBDE) congeners. Results from these analyses were combined with others previously published to yield a data set of 18 tri- to hepta-substituted PBDE congeners in 102 animals sampled over a span of 19 year (females) and 34 year (males). In females, mean total PBDE concentrations increased between 1996 and 2015 by approximately 50%, from 1940 to 2780 pg/g wet wt., although not significantly so (p > 0.05) by one-way ANOVA. In males, concentrations ranged from 376 to 6470 pg/g wet wt. between 1981 and 2015 (p

Fatty acids have been widely used as trophic biomarkers in marine mammals. However, for the South American sea lion, the most abundant otariid in the eastern South Pacific, there is no information about blubber fatty acids and their link to diet. Here, we compare fatty acid profiles of sea lions from two distinct oceanographic regions in northern and southern Chile. Their fatty acids vary greatly between regions, suggesting dietary differences at a spatial scale. The fatty acid C22:6ω3 was more abundant in sea lions from the northern region, likely associated with consumption of anchovy, cephalopods, and crustaceans, which are rich in that fatty acid, and have been reported as their main prey items. Sea lions from the southern region were richer in C22:1 and C20:1, characteristic of teleost fish, suggesting a piscivorous diet. Males displayed a more diverse fatty acid composition than females, suggesting a wider trophic niche. Few individual sea lions within the southern region had unusually high levels of C18:2ω6, commonly found in terrestrial environments. This suggests consumption of farmed salmon, whose diet is usually based on terrestrial sources. This demonstrates how human intervention is being reflected in the tissues of a top predator in a natural environment.

Polychlorinated biphenyls (PCBs) are toxic, persistent, and lipophilic chemical compounds that accumulate to high levels in harbor porpoises (Phocoena phocoena) and other cetaceans. It is important to monitor PCBs in wildlife, particularly in highly exposed populations to understand if concentrations are declining and how levels relate to toxicological thresholds and indices of health like infectious disease mortality. Here we show, using generalized additive models and tissue samples of 814 U.K.-stranded harbor porpoises collected between 1990 and 2017, that mean blubber PCB concentrations have fallen below the proposed thresholds for toxic effects. However, we found they are still associated with increased rates of infectious disease mortality such that an increase in PCB blubber concentrations of 1 mg kg-1 lipid corresponds with a 5% increase in risk of infectious disease mortality. Moreover, rates of decline and levels varied geographically, and the overall rate of decline is slow in comparison to other pollutants. We believe this is evidence of long-term preservation in the population and continued environmental contamination from diffuse sources. Our findings have serious implications for the management of PCB contamination in the U.K. and reinforce the need to prevent PCBs entering the marine environment to ensure that levels continue to decline.

[Abstract] Some species of sea turtles have wide distribution ranges and therefore need mechanisms to cope with latitudinal changes in temperature that could negatively affect metabolism and molecular functions. The objective of this work is to collect the available scientific information on these mechanisms. After the review, four types of mechanisms have been found in the different species: behavioral, physiological, body mass and fat accumulation. The leatherback turtle, whose range of distribution is the largest of all, has the most specialized mechanisms, such as the accumulation of blubber and brown fat. We conclude that the mechanisms discovered until now seem to be enough to allow the adaptation of turtles to different temperatures, both higher and lower, but there is also a great lack of information in this regard. [Resumen] Algunas especies de tortugas marinas presentan amplios rangos de distribución y, por tanto, necesitan mecanismos para hacer frente a los cambios latitudinales de temperatura que podrían afectar negativamente a su metabolismo y funciones moleculares. El objetivo de este trabajo es recopilar la información científica disponible sobre estos mecanismos. Tras la revisión se han encontrado cuatro tipos de mecanismos en las diferentes especies: de comportamiento, fisiológicos, masa corporal y la acumulación de grasa. La tortuga laúd, cuyo rango de distribución es el mayor de todos, posee los mecanismos más especializados, como la acumulación de “grasa de ballena” y grasa parda. Concluimos que los mecanismos descubiertos hasta el momento parecen ser suficientes para permitir la adaptación de las tortugas a diferentes temperaturas, tanto más altas como bajas, pero también se evidenció una gran falta de información al respecto. [Resumo] Algunhas especies de tartarugas mariñas teñen amplos intervalos de distribución e, polo tanto, necesitan mecanismos para facer fronte aos cambios latitudinais na temperatura que poden afectar negativamente ao seu metabolismo e funcións moleculares. O obxectivo deste traballo é recoller a información científica dispoñible sobre estes mecanismos. Tras a revisión, atopáronse catro tipos de mecanismos nas distintas especies: de comportamento, fisiolóxicos, masa corporal e acumulación de graxa. A tartaruga laúd, cuxo rango de distribución é o maior de todos, posúe os mecanismos máis especializados, como a acumulación de "graxa de balea" e graxa marrón. Concluímos que os mecanismos descubertos ata agora parecen ser suficientes para permitir a adaptación das tartarugas ás diferentes temperaturas, tanto máis altas como baixas, pero tamén se evidenciou unha gran falta de información ao respecto. Traballo fin de grao (UDC.CIE). Bioloxía. Curso 2021/2022

Более высокие прочностные показатели получаются при использовании сульфатированных и сульфированных жиров. Также минеральное масло и нейтральные глицериды (говяжий и технический жир) повышают выносливость кожи примерно в 2-3 раза по отношению к нежированной. Повышение предела прочности кожи в результате жирования зависит от природы жирующего материала., It is known that the increase in the tensile strength of the skin as a result of greasing depends on the nature of the greasing material. Higher strength indicators are obtained when using sulfated and sulfonated fats. More mineral oil and neutral glycerides (beef and technical fat) increase the endurance of the skin by about 2-3 times in relation to non-oily.

Altres ajuts: acords transformatius de la UAB The impacts of environmental changes and anthropogenic threats in marine mammals are a growing concern for their conservation. In recent years, efforts have been directed to understand how marine mammals cope with stressors and to assess and validate stress biomarkers, mainly levels of glucocorticoid hormones (e.g. cortisol) in certain body tissues. The aims of this study were to assess the impact of different causes of stranding (chronically affected and bycaught striped dolphins) on cortisol concentrations in serum and in blubber; and to evaluate the association between cortisol levels in these tissues. Blubber and blood samples were collected from striped dolphins (n = 42) stranded on the Mediterranean coast between 2012 and 2018. Cortisol concentrations were measured by using enzyme immunoassay. A high correlation was found between circulating and blubber cortisol concentrations (R = 0.85, p < 0.01). Necropsies and pathological studies concluded that a third of the dolphins were bycaught in fishing nets and released by fishermen (Bycaught animals group), while the other two thirds were euthanized, or died, due to a disease or chronic condition (e.g. calves separated from the mother or animals infected with dolphin morbillivirus or Brucella ceti) that impeded survival (Chronically affected animals group). Cortisol concentrations (mean ± SD) were six times higher in chronically affected animals (35.3 ± 23 ng cortisol/g blubber and 6.63 ± 3.22 μg cortisol/dl serum) compared to those bycaught in fishing nets (6.2 ± 4.3 ng cortisol/g blubber and 1.15 ± 1.51 μg cortisol/dl serum). Results suggests that serum and blubber cortisol concentrations can contribute in inferring the overall health and welfare of free-ranging cetaceans. However, further research is required to understand better the kinetics of blubber cortisol incorporation and removal, the factors involved in these processes, and the local conversion of cortisol in the blubber.

Funding: The work was funded from core support given to the Sea Mammal Research Unit, Scottish Oceans Institute, from the Natural Environmental Research Council (United Kingdom). True, phocid seals have the shortest known lactations relative to body mass, during which mass transfer of adipose stores from mother to offspring occurs at an unrivalled rate and extent. The mothers of most species of seal fast until weaning whilst their pups gorge on the most fat-rich milks known. This results in a dramatic reduction in maternal blubber mass while pups may triple their body weights before weaning. Mothers mobilise their blubber fat, transport it via blood to their mammary glands and into milk, whilst pups transfer fat in the opposite direction, from their intestines, via blood, to their blubber. Using proteomic analysis of mother and pup sera from Atlantic grey seals, we find that this mirror image flux of lipids between mothers and pups is reflected in an almost inverse relationship in the proteins in their blood specialised to transport fats, lipids, and fat-soluble vitamins. For instance, apolipoproteins ApoB-48/100, ApoA-II and ApoA-IV, which are structural components of the main lipid carrier complexes such as chylomicrons and HDL particles, occur at much higher levels in pups than mothers. Meanwhile, carriers of fat-soluble vitamins such as retinol- and vitamin D-binding proteins are lower in pups and gradually build towards weaning. In contrast, sex hormone-binding globulin occurs at remarkably high relative concentrations in pups. There are therefore dramatic differences between, and an unrealised complexity in, the balance of proteins involved in the rapid transfer of fats and other lipids from mother to pups in preparing their offspring for their post-weaning fasts on land and eventual survival at sea before they can feed again. Publisher PDF

The stratification of blubber fatty acids (FAs) is a widely used strategy in marine mammals and can be influenced by many factors, including their diet, environmental temperature, and physiological status. There are 3 distinct finless porpoise species/subspecies in Chinese coastal and inland waters in a wide range from 20°N to 40°N. The biochemical stratification of the blubbers of finless porpoises in different regions may provide valuable information for understanding their environmental adaptations. The FA compositions of 4 geographic populations of finless porpoise (FP) collected from the Bohai Gulf, East China Sea, South China Sea, and Yangtze River were therefore analyzed and compared. The blubber FA compositions of finless porpoises were dominated by ΣMUFAs, followed by ΣSFAs and ΣPUFAs, and were generally consistent with those of other cetaceans. The blubber of finless porpoises was significantly stratified with increasing levels of ΣMUFAs and decreasing levels of ΣSFAs and ΣPUFAs from the inner to the outer layers. The 3 marine populations shared more similarities in their FA compositions and stratifications compared to the freshwater porpoises, particularly regarding the PUFAs in the inner layers, which might have been mainly influenced by the diet compositions of marine and freshwater porpoises. Contrary to what was expected, in the 3 marine populations, the SFA and MUFA levels showed opposite correlations (negative and positive, respectively) with habitat temperatures, possibly indicating an adaptation mechanism in finless porpoises characterized by a trade-off between the insulation and fluidity properties of the blubber through the adjustment of the compositions and gradients of MUFAs and SFAs across the blubber depth in response to environmental temperature/latitude changes.

Significance Divergent lineages can respond to common environmental factors through convergent processes involving shared genomic components or pathways, but the molecular mechanisms are poorly understood. Here, we provide genomic resources and insights into the evolution of mammalian lineages adapting to aquatic life. Our data suggest convergent evolution, for example, in association with thermoregulation through genes associated with a surface heat barrier (NFIA) and internal heat exchange (SEMA3E). Combined with the support of previous reports showing that the UCP1 locus has been lost in many marine mammals independently, our results suggest that the thermostatic strategy of marine mammals shifted from enhancing heat production to limiting heat loss., The ancestors of marine mammals once roamed the land and independently committed to an aquatic lifestyle. These macroevolutionary transitions have intrigued scientists for centuries. Here, we generated high-quality genome assemblies of 17 marine mammals (11 cetaceans and six pinnipeds), including eight assemblies at the chromosome level. Incorporating previously published data, we reconstructed the marine mammal phylogeny and population histories and identified numerous idiosyncratic and convergent genomic variations that possibly contributed to the transition from land to water in marine mammal lineages. Genes associated with the formation of blubber (NFIA), vascular development (SEMA3E), and heat production by brown adipose tissue (UCP1) had unique changes that may contribute to marine mammal thermoregulation. We also observed many lineage-specific changes in the marine mammals, including genes associated with deep diving and navigation. Our study advances understanding of the timing, pattern, and molecular changes associated with the evolution of mammalian lineages adapting to aquatic life.

Excessive adiposity is associated with altered oxygen tension and comorbidities in humans. In contrast, marine mammals have high adiposity with no apparent detrimental effects. However, partial pressure of oxygen (Po2) in their subcutaneous adipose tissue (blubber) and its relationship with fatness have not been reported. We measured Po2 and temperature at different blubber depths in 12 healthy juvenile grey seals. Fatness was estimated from blubber thickness and morphometric parameters. Simultaneously, we monitored breathing pattern; heart rate and arterial blood saturation with a pulse oximeter; and relative changes in total hemoglobin, deoxyhemoglobin, and oxyhemoglobin in blubber capillaries using near‐infrared spectroscopy (NIRS) as proxies for local oxygenation changes. Blubber Po2 ranged from 14.5 to 71.4 mmHg (39.2 ± 14.1 mmHg), which is similar to values reported in other species. Blubber Po2 was strongly and negatively associated with fatness (LME: p, Grey seals blubber Po2 is similar to that measured in other mammal species and negatively associated with fatness, independently of depth of measurement, oxygen delivery, or temperature.

Climate change may affect temporal trends of persistent organic pollutants (POPs) in Arctic wildlife. We studied how biological and climate variables influence temporal trends of selected POP groups in landlocked Arctic char muscle and in ringed seal blubber from West and East Greenland. The variables included fish length or animal age, sex, a stable nitrogen isotope, sea ice extent, air or seawater temperature, salinity and the Arctic Oscillation Index (AOI). Model selection for multiple regression showed that the most important predictors varied among POP groups, species and region. Decreasing time trends were found for all POP groups with the exception of hexachlorobenzene (HCB) concentration which remained stable in Arctic char and ringed seals from West Greenland. When retained in the most parsimonious model, the AOI was positively associated with POP concentrations for East Greenland seals, but negatively for West Greenland seals. Seawater temperature and sea ice extent were positively associated with POP concentrations. The effects of explanatory variables on the annual rates of change in POP concentrations were relatively minor relative to the decline caused by reduction in POP emissions following national and international regulations introduced since the 1970s.

Antarctic is still considered one of the few pristine areas in the globe. Despite this, several studies have shown phased out organic pollutants are present in several environmental abiotic and biological compartments. This study, based on blubber and fecal samples collected from five species of Antarctic pinnipeds assessed the relationship between organochlorine pesticides (OCs) levels and trophic characterization using stable isotope analysis (δ 13 C & δ 15 N). The prevailing pollutants found in blubber were HCHs, HCB, Heptachlor and Aldrin (100–500 ng g −1 l.w.). We also report the presence of Endrin, Endosulfan and Methoxychlor in feces which have not been detected at these magnitudes before in the same species and could be suggesting a detoxification mechanism. All the species tend to high trophic positions (3.4–4.9), but with considerable variation in trophic niche and organochlorine pesticides concentrations per sampling site. This finding suggests that differences in pesticide levels in individuals are associated to foraging ecology.

Respiratory vapour ("blow") has been successfully used as a sample matrix for reproductive and adrenal endocrine assessments of some captive cetacean species. Given that the accuracy of blow hormone measurements can be affected by seawater contamination, variable sample volumes, and respiratory water dilution, it is a much more difficult technique to use for studies on wild cetaceans. Herein, we aimed to determine if blow sampling was a viable technique to measure reproductive and adrenal hormone concentrations in humpback whales (Megaptera novaeangliae). To achieve this, concentrations of progesterone, testosterone, oestradiol, and cortisol were measured in paired blow and blubber samples collected from free-swimming whales (n = 48). Hormone concentrations were compared between sample types and examined in relation to a whale's demographic class and the season when it was sampled. Testosterone concentrations were poorly correlated between sample types. In contrast, blubber concentration had a significant impact on the fit of the blow progesterone, oestradiol, and cortisol models (chi(2) = [11.52, 22.57, 6.121, p = [< 0.001, < 0.001, 0.013], respectively). There was little further evidence that blow hormone concentrations were driven by the physiological condition of a whale. Overall, the, strongest evidence came from one adult female who was presumed to be pregnant based on her blubber progesterone concentration (9.97 ng/g). This adult female displayed a blow progesterone concentration of 0.94 ng/mL, which was markedly higher than all other adult females and most other whales with the exception of two. Currently, however, blubber sampling is the preferred option for studying the endocrinology of humpback whales, primarily due to the ease of sample collection and robustness of hormone analyses. Further refinements and validation tests are required before blow hormone monitoring can he used as a non-invasive alternative.

We would like to thank the funders: the Department for Environment Food and Rural Affairs and Marine Scotland, for a number of long‐term monitoring contracts awarded to SMASS, the Sea Mammal Research Unit National Capability Funding from the Natural Environment Research Council (grant no. SMRU 10001), and the Strategic Environmental Research and Development Program (award RC‐2337). Measuring the energy stores, or body condition, of cetaceans is vital for monitoring population health. Cetaceans are exposed to a range of anthropogenic stressors, including, for example, noise, contaminants, habitat degradation, reduced prey availability, ship strike, and entanglement. Tools to assess body condition in these inaccessible and vulnerable animals are required to better understand the energetic consequences of anthropogenic stressors that can impact population health and, ultimately, conservation status.Remotely obtained, dart biopsy samples are becoming an increasingly standard method of tissue collection from live, large cetaceans. Here, the potential applicability of using total lipid content in such biopsy samples to estimate overall body condition was assessed using full‐depth dorsal blubber samples from stranded ziphiids (n = 8) and balaenopterids (n = 9). First, variation in total lipid content through the blubber depth was investigated to assess the representativeness of shallow‐depth dart biopsies taken from live animals. Second, how lipid content varies by species, cause of death, sex, age class, and morphometric indices of body condition was assessed to evaluate what information about individual energy stores can be gained from such analyses. Total lipid content in dorsal, shallow‐depth blubber biopsy samples from both cetacean families provides little information on overall body condition. Stratification of lipid content through the blubber layer in the balaenopterids means that superficial biopsy samples are not representative of the lipid stores available for mobilization through the rest of the tissue. A lack of variation in blubber lipid content, both within and between the ziphiid individuals, resulted in no ability to correlate these measures with morphometrics or other health, sex, or age class covariates.Other potential markers in the blubber from remote biopsy sampling should be explored in order to further develop robust tools for estimating the body condition of free‐ranging cetaceans. Postprint

Persistent organic pollutants (POPs) were analyzed in eighteen blubber samples biopsied from fin whales (Balaenoptera physalus) during the feeding season near the Antarctic Peninsula in the summer of 2013. POP content (in ng g-1 lipid weight) ranged from 46.4 to 708 for polychlorinated biphenyls (∑PCBs), 6.77 to 123 for hexachlorobenzene (HCB), 10.1 to 489 for dichlorodiphenyltrichloroethane and derivatives (∑DDTs), 5.38 to 52.8 for hexachlorocyclohexanes (∑HCH) and

Elevated concentrations of persistent organic pollutants (POPs) and emerging halogenated flame retardants (HFRs) have been reported in tissues of the endangered St. Lawrence Estuary (Canada) beluga population as well as in minke whales visiting that same feeding area. This study examined the linkages between blubber concentrations of POPs and emerging HFRs, and transcription in skin of genes involved in the regulation of thyroid and steroid axes in belugas and minke whales from the St. Lawrence Estuary. In belugas, concentrations of PCBs, OCs and hexabromobenzene (HBB) were positively correlated with the transcription of thyroid- and/or steroid-related genes, while Dec-604 CB concentrations were negatively associated with the transcription of glucocorticoid and thyroid genes. In minke whales, PBDE concentrations changed positively with Esrβ transcript levels and HBB concentrations negatively with Nr3c1 transcripts. Present results suggest that several biological functions including reproduction and energetic metabolism may represent potential targets for organohalogens in these whales.

Twelve persistent organic pollutants (POPs) were measured in 11 tissue samples from a pregnant sperm whale stranded on the Huizhou coast of the South China Sea, China, in March 2017. POPs were found to be more concentrated in the irrigated tissues such as placenta, ovary, mammary gland, and liver than the less irrigated tissues such as epidermis. High POP levels detected in the placenta might result in abnormal hormone secretion in the placenta, which would affect the unborn offspring. We hypothesized that ovary is potentially vulnerable to the exposure of higher contaminant levels. The PAH concentrations were higher in the lung than in other tissues, which suggest that PAH levels in the lung were breath-dependent in the sperm whale. The concentrations of POPs except PAHs in the sperm whale blubber were lower than those in the same species in the Northern Hemisphere and were comparable to or lower than those in the same species in the Southern Hemisphere.

Short-chain chlorinated paraffins (SCCPs) are particularly prone to environmental dispersal through long range atmospheric transport. Consequently, they have been detected in biota and environmental matrices at both the North Pole and South Pole. This study shows the first detection of SCCPs in southern hemisphere humpback whales feeding in Antarctic waters. Blubber of specimens stranded along the Australian coastline was analysed and SCCPs were detected in 7 out of 9 individuals. Levels of SCCPs detected in this study were generally low with concentrations up to only 46 ng/g lw. These results were significantly lower than those detected in Northern Hemisphere odontocetes from previous studies, although no reported burdens in northern hemisphere baleen whales are available for comparison. Both the highest level and lowest ( C13. Further investigation is needed in order to evaluate the presence and distribution of SCCPs in the remote Antarctica ecosystem, and delineate longer term environmental consequences of recent inclusion of SCCPs under Annex A of the Stockholm Convention, securing their phase out in ratifying nations.

The common bottlenose dolphin (Tursiops truncatus) is a carnivorous cetacean that thrives in marine environments, one of the apex predators of the marine food web. They are found in coastal and estuarine ecosystems, which are known to be sensitive to environmental impacts. Dolphins are considered sentinel organisms for monitoring the health of coastal marine ecosystems due to their role as predators that can bioaccumulate contaminants. Although recent studies have focused on capturing the circulating metabolomes of these mammals, and in the context of pollutants and exposures in the marine environment, skin and blubber are important surface and protective tissues that have not been adequately probed for metabolism. Using a proton nuclear magnetic resonance spectroscopy (1H NMR) based metabolomics approach, we quantified 51 metabolites belonging to 74 different metabolic pathways in the skin and blubber of stranded bottlenose dolphin (n = 4) samples collected at different localities in the Southern Zone coast of Yucatan Peninsula of Mexico. Results indicate that metabolism of skin and blubber are quantitatively very different. These metabolite abundances could help discriminate the tissue-types using supervised partial least square regression discriminant analysis (PLSDA). Further, using hierarchical clustering analysis and random forest analysis of the metabolite abundances, the results pointed to unique metabolites that are important classifiers of the tissue-type. On one hand, the differential metabolic patterns, mainly linking fatty acid metabolism and ketogenic amino acids, seem to constitute a characteristic of blubber, thus pointing to fat synthesis and deposition. On the other hand, the skin showed several metabolites involved in gluconeogenic pathways, pointing towards an active anabolic energy-generating metabolism. The most notable pathways found in both tissues included: urea cycle, nucleotide metabolism, amino acid metabolism, glutathione metabolism among others. Our 1H NMR metabolomics analysis allowed the quantification of metabolites associated with these two organs, i.e., pyruvic acid, arginine, ornithine, 2-hydroxybutyric acid, 3-hydroxyisobutyric acid, and acetic acid, as discriminatory and classifying metabolites. These results would lead to further understanding of the functional and physiological roles of dolphin skin and blubber metabolism for better efforts in their conservation, as well as useful target biopsy tissues for monitoring of dolphin health conditions in marine pollution and ecotoxicology studies.

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.

Cetaceans in the Southern California Bight (SCB) are exposed to high levels of halogenated organic contaminants (HOCs), which have previously been linked to impaired reproductive health and immune responses. We used a combination of molecular tools to examine the potential physiological impacts of HOC exposure in two bottlenose dolphin ( Tursiops truncatus) ecotypes in the SCB. We quantified 25 HOCs in the blubber of 22 biopsies collected from males between 2012 and 2016. We then analyzed genome-wide gene expression in skin using RNA-sequencing and measured blubber testosterone to compare HOC exposure with cellular and endocrine biomarkers. We found high levels of HOCs in both ecotypes with significantly higher total polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), tris(4-chlorophenyl)methanol (TCPMOH), and chlordane-related compounds in the coastal ecotype versus the offshore ecotype. We found evidence of PBDE bioaccumulation in both ecotypes, however, the pattern of bioaccumulation or endocrine disruption for other HOCs was different between the ecotypes, suggesting potential endocrine disruption in the coastal ecotype. We also observed correlations between HOCs and gene coexpression networks enriched for xenobiotic metabolism, hormone metabolism, and immune response that could indicate cellular effects from HOC exposure. By integrating measurements of HOC load with both transcriptome profiling and endocrine biomarkers, our approach provides insight into HOC exposure and potential impacts on wild cetacean health in southern California.

Here we provide a first assessment of microplastics (MPs) in stomach contents of 15 common dolphins (Delphinus delphis) from both single and mass stranding events along the New Zealand coast between 2019 and 2020. MPs were observed in all examined individuals, with an average of 7.8 pieces per stomach. Most MPs were fragments (77%, n = 90) as opposed to fibres (23%, n = 27), with translucent/clear (46%) the most prevalent colour. Fourier transform infrared (FTIR) spectroscopy revealed polyethylene terephthalate (65%) as the most predominant polymer in fibres, whereas polypropylene (31%) and acrylonitrile butadiene styrene (20%) were more frequently recorded as fragments. Mean fragment and fibre size was 584 μm and 1567 μm, respectively. No correlation between total number of MPs and biological parameters (total body length, age, sexual maturity, axillary girth, or blubber thickness) was observed, with similar levels of MPs observed between each of the mass stranding events. Considering MPs are being increasingly linked to a wide range of deleterious effects across taxa, these findings in a typically pelagic marine sentinel species warrants further investigation.

The long-term program of research on grey seals at the Isle of May was funded by the SMRU National Capability funding from the UKRI Natural Environment Research Council (NERC) (grant number SMRU 1001). KAB and HA were funded by NERC grant NE/M013723/1 and AJH and KJR were funded by NE/M01357X/1 for this project. Persistent organic pollutants (POPs) are endocrine disruptors that alter adipose tissue development, regulation and function. Top marine predators are particularly vulnerable because they possess large fat stores that accumulate POPs. However, links between endocrine or adipose tissue function disruption and whole animal energetics have rarely been investigated. We predicted the impact of alterations to blubber metabolic characteristics and circulating thyroid hormone (TH) levels associated with polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) on suckling mass gain and weaning mass in wild grey seal pups. Glucose uptake by inner blubber was a strong predictor of whole animal mass gain rate, which in turn, resulted in heavier weaning mass. Weaning mass was predicted to increase by 3.7 ± 1.59 (sem) %, through increased mass gain rate, in the absence of the previously reported suppressive effect of dioxin-like PCB (DL-PCBs) on blubber glucose uptake. PBDEs were, conversely, associated with faster mass gain. Alleviation of this effect was predicted to reduce weaning mass by 6.02 ± 1.86% (sem). To better predict POPs effects on energy balance, it is crucial to determine if and how PBDEs promote mass gain in grey seal pups. Weaning mass was negatively related to total T3 (TT3) levels. A 20% (range = 9.3–31.7%) reduction in TT3 by DL-PCBs partially overcame the effect of DL-PCB -mediated reduction in blubber glucose uptake. Overall, DL-PCBs were thus predicted to reduce weaning mass by 1.86 ± 1.60%. Organohalogen impacts on whole-animal energy balance in grey seal pups appear to partially offset each other through opposing effects on different mechanisms. POP effects were generally minor, but the largest POP-induced reductions in weaning mass were predicted to occur in pups that were already small. Since weaning mass is positively related to first-year survival, POPs may disproportionately affect smaller individuals, and could continue to have population-level impacts even when levels are relatively low compared to historical values. Our findings show how in vitro experiments combined with measurements in vivo can help elucidate mechanisms that underpin energy balance regulation and help to quantify the magnitude of disruptive effects by contaminants and other stressors in wildlife. Publisher PDF

Studies of predator feeding ecology commonly focus on energy intake. However, captive predators have been documented to selectively feed to optimize macronutrient intake. As many apex predators experience environmental changes that affect prey availability, limitations on selective feeding can affect energetics and health. We estimated the protein:fat ratio of diets consumed by wild polar bears using a novel isotope-based approach, measured protein:fat ratios selected by zoo polar bears offered dietary choice and examined potential energetic and health consequences of overconsuming protein. Dietary protein levels selected by wild and zoo polar bears were low and similar to selection observed in omnivorous brown bears, which reduced energy intake requirements by 70% compared with lean meat diets. Higher-protein diets fed to zoo polar bears during normal care were concurrent with high rates of mortality from kidney disease and liver cancer. Our results suggest that polar bears have low protein requirements and that limitations on selective consumption of marine mammal blubber consequent to climate change could meaningfully increase their energetic costs. Although bear protein requirements appear lower than those of other carnivores, the energetic and health consequences of protein overconsumption identified in this study have the potential to affect a wide range of taxa.

Alaskan harbour seal populations are currently listed as a species of special concern. Although there is evidence of recent stabilization or even partial recovery of harbour seal numbers in areas of historic decline, most populations have not made substantial recoveries. To date, few data exist regarding spatial and seasonal changes in blubber fatty acids (FAs) for Alaskan harbour seal populations. The purpose of this study was to qualitatively investigate harbour seal blubber FA profiles for regional, seasonal and age class differences. Blubber FA concentrations were analysed using MANOVA and linear discriminant analysis (LDA) from 760 individual harbour seals across Bristol Bay, Kodiak, Prince William Sound and Southeast Alaska from 1997 to 2010. Our results suggest spatial and seasonal differences are largely driven by monounsaturated FAs, most notably 14:1n-5, 16:1n-7 and 18:1n-7. In addition, our data revealed a progression in blubber FAs from pups to adults, with a shift from saturated FAs and short-chained monounsaturated FAs in the pup blubber to more long-chain monounsaturated FAs and polyunsaturated FAs in adults. Lastly, harbour seals pups had elevated saturated FA 16:0 concentrations when compared to other age classes, regardless of location or period. With this vast spatial and seasonal FA information, we believe future sampling of blubber FAs from Alaskan harbour seal populations could be a useful tool in assessing the response of this species and its ecosystem to changes associated with natural and anthropogenic pressures.

Marine mammal body composition has been an important tool that is used as a proxy for the health and condition of individuals within a population. Common bottlenose dolphin (Tursiops truncatus) body composition is influenced by variations in blubber thickness resulting from changes in temperature, prey availability, health, and life-history traits. We examined how environmental, ontogenetic, and reproductive variables influenced the body composition of common bottlenose dolphins in Sarasota Bay using data collected from a long-term monitoring project by the Sarasota Dolphin Research Program (SDRP). We found that both sea surface temperature (SST) and catch per unit effort (CPUE), used as a proxy for prey availability, influenced body composition. There was a high degree of seasonality in body composition, with higher values occurring in winter when SST and CPUE were both low. Ontogeny also greatly influenced body composition, as younger dolphins typically had thicker blubber than mature individuals. Interestingly, young females allocated more energy to allometric growth than deposition of blubber for body composition when compared to young males. However, as females matured and their growth slowed, they invested more in body composition. We found no significant difference in body composition of females of varying reproductive states, providing further evidence of their status as true income breeders. Our work highlights that changes in body composition result from fluctuations in environmental variables and that energy allocation to body composition changes with ontogeny.

Kelp gulls Larus dominicanus (KG) feed on the skin and blubber of living southern right whales Eubalaena australis (SRWs) off Península Valdés (PV), Argentina. The whales respond strongly to KG micropredation by changing their immediate (acute) behavior during attacks and their overall (chronic) surfacing pattern and body posture to minimize gull exposure. The energetic and large-scale behavioral consequences of these attacks are unknown. To address this knowledge gap, we quantified the effect size of both acute (during attacks) and chronic (not during attacks) responses by comparing the respiration rates, swim speed, and nursing behavior of PV SRWs to undisturbed (control) SRW mother-calf pairs in Head of Bight, Australia, using unmanned aerial vehicle focal follows. Even when gulls were not attacking, PV SRW mothers and calves demonstrated ~50 and ~25% higher respiration rates, respectively, than whales in Australia. During attacks, PV calf respiration rates increased by an additional 10%. PV SRW mothers also frequently (>76% of respirations) exhibited irregular breathing postures, causing the whales to potentially expend extra energy by working against their natural buoyancy. Despite no significant increase in average maternal swim speed, 76 and 90% of gull attacks elicited strong behavioral reactions from mothers and calves, respectively. Overall, PV calves spent less time nursing during individual bouts compared to those in Australia but entered suckling position more frequently. Furthermore, kelp gulls seemed to show a preference for attacking previously wounded calves and at a higher rate. These chronic and acute behavioral effects may carry energetic costs, which could have long-term consequences for SRW survival and reproduction.

Polychlorinated biphenyls (PCBs) are highly toxic and persistent aquatic pollutants that are known to bioaccumulate in a variety of marine mammals. They have been associated with reduced recruitment rates and population declines in multiple species. Evidence to date documents effects of PCB exposures on female reproduction, but few studies have investigated whether PCB exposure impacts male fertility. Using blubber tissue samples of 99 adult and 168 juvenile UK-stranded harbour porpoises (Phocoena phocoena) collected between 1991 and 2017, here we show that PCBs exposures are associated with reduced testes weights in adults with good body condition. In animals with poor body condition, however, the impact of PCBs on testes weights was reduced, conceivably due to testes weights being limited by nutritional stress. This is the first study to investigate the relationship between PCB contaminant burden and testes weights in cetaceans and represents a substantial advance in our understanding of the relationship between PCB exposures and male reproductive biology in cetaceans. As testes weight is a strong indicator of male fertility in seasonally breeding mammals, we suggest the inclusion of such effects in population level impact assessments involving PCB exposures. Given the re-emergent PCB threat our findings are globally significant, with potentially serious implications for long-lived mammals. We show that more effective PCB controls could have a substantial impact on the reproductive health of coastal cetacean species and that management actions may need to be escalated to ensure adequate protection of the most vulnerable cetacean populations. Defra; Natural Environment Research Council (NERC) grant NE/L002485/1; Bertarelli Foundation through the Bertarelli Programme in Marine Science; partially funded by NERC grant NE/S000100/1 supporting the ChemPop project.