Exploring the body condition of gray whales (Eschrichtius robustus) through adipocyte analysis during unusual mortality events.

The blubber is the characteristic fatty tissue of most marine mammals; it comprises adipocytes, blood vessels, lymphatics, and abundant collagen and elastic fibers. Containing the reserve of excess and accumulated energy from feeding. Previous studies found that the adipocyte area may change according to the amount of accumulated and expended energy during migration, reproduction, lactation and breeding. This cellular characteristic reflects the energetic status of an individual (i.e., the balance between intake and total energy investment), which can be interpreted as reproductive success and general health. In the present study, we measured the adipocyte area of the gray whales wintering in Laguna San Ignacio, Baja California Sur, Mexico, to evaluate body condition. Adipose tissue was sampled from 116 individuals (31 calves, 22 mothers, and 63 solitary individuals) over a study period of 62 days. Each whale was assigned a priori body condition (good, fair, poor). Histological preparations stained with hematoxylin-eosin were microphotographs used to measure the adipocyte area with the software Adiposoft as a plugin to ImageJ. The adipocyte area of the calves was significantly lower than that of the adults and showed an increase during the study period. The three body condition categories found no differences in the adipocyte area. The adipocyte area analysis applied in the present study appears to be a useful tool in assessing body condition in calves, although it appears to be limited to adults. According to the OneHealth paradigm, environmental health is closely related to the health of the gray whale, which in turn is related to public health and the socioeconomic well-being of local communities that use this species as a resource.

Phthalates and fatty acid markers in free-ranging cetaceans from an insular oceanic region: Ecological niches as drivers of contamination.

Plastic additives, such as phthalates, are ubiquitous contaminants that can have detrimental impacts on marine organisms and overall ecosystems' health. Valuable information about the status and resilience of marine ecosystems can be obtained through the monitoring of key indicator species, such as cetaceans. In this study, fatty acid profiles and phthalates were examined in blubber biopsies of free-ranging individuals from two delphinid species (short-finned pilot whale - Globicephala macrorhynchus, n = 45; common bottlenose dolphin - Tursiops truncatus, n = 39) off Madeira Island (NE Atlantic). This investigation aimed to explore the relations between trophic niches (epipelagic vs. mesopelagic), contamination levels, and the health status of individuals within different ecological and biological groups (defined by species, residency patterns and sex). Multivariate analysis of selected dietary fatty acids revealed a clear niche segregation between the two species. Di-n-butylphthalate (DBP), diethyl phthalate (DEP), and bis(2-ethylhexyl) phthalate (DEHP) were the most prevalent among the seven studied phthalates, with the highest concentration reached by DEHP in a bottlenose dolphin (4697.34 ± 113.45 ng/g). Phthalates esters (PAEs) concentration were higher in bottlenose dolphins (Mean ∑ PAEs: 947.56 ± 1558.34 ng/g) compared to pilot whales (Mean ∑ PAEs: 229.98 ± 158.86 ng/g). In bottlenose dolphins, DEHP was the predominant phthalate, whereas in pilot whales, DEP and DBP were more prevalent. Health markers suggested pilot whales might suffer from poorer physiological conditions than bottlenose dolphins, although high metabolic differences were seen between the two species. Phthalate levels showed no differences by ecological or biological groups, seasons, or years. This study is the first to assess the extent of plastic additive contamination in free-ranging cetaceans from a remote oceanic island system, underscoring the intricate relationship between ecological niches and contaminant exposure. Monitoring these chemicals and their potential impacts is vital to assess wild population health, inform conservation strategies, and protect critical species and habitats.

Proteome profiling reveals opportunities to investigate biomarkers of oxidative stress and immune responses in blubber biopsies from free-ranging baleen whales.

Over 25% of cetacean species worldwide are listed as critically endangered, endangered or vulnerable by the International Union for Conservation of Nature. Objective and widely applicable tools to assess cetacean health are therefore vital for population monitoring and to inform conservation initiatives. Novel blubber biomarkers of physiological state are examples of such tools that could be used to assess overall health. Proteins extracted from blubber likely originate from both the circulation and various cell types within the tissue itself, and their expression is responsive to signals originating from other organs and the nervous system. Blubber proteins can therefore capture information on physiological stressors experienced by individuals at the time of sampling. For the first time, we assess the feasibility of applying shotgun proteomics to blubber biopsy samples collected from free-ranging baleen whales. Samples were collected from minke whales (Balaenoptera acutorostrata) (n = 10) in the Gulf of St Lawrence, Canada. Total protein was extracted using a RIPA cell lysis and extraction buffer-based protocol. Extracted proteins were separated and identified using nanoflow Liquid Chromatography Electrospray Ionization in tandem with Mass Spectrometry. We mapped proteins to known biological pathways and determined whether they were significantly enriched based on the proteome profile. A pathway enrichment map was created to visualize overlap in tissue-level biological processes. Amongst the most significantly enriched biological pathways were those involved in immune system function: inflammatory responses, leukocyte-mediated immunity and the humoral immune response. Pathways associated with responses to oxidative stress were also enriched. Using a suite of such protein biomarkers has the potential to better assess the overall health and physiological state of live individuals through remote biopsy sampling. This information is vital for population health assessments to predict population trajectories, and ultimately guide and monitor conservation priorities and initiatives.

Demographic and physiological signals of reproductive events in humpback whales on a southwest pacific breeding ground.

The field of marine mammal conservation has dramatically benefited from the rapid advancement of methods to assess the reproductive physiology of individuals and populations from steroid hormones isolated from minimally invasive skin-blubber biopsy samples. Historically, this vital information was only available from complete anatomical and physiological investigations of samples collected during commercial or indigenous whaling. Humpback whales (Megaptera novaeangliae) are a migratory, cosmopolitan species that reproduce in warm, low-latitude breeding grounds. New Caledonia is seasonally visited by a small breeding sub-stock of humpback whales, forming part of the endangered Oceania subpopulation. To better understand the demographic and seasonal patterns of reproductive physiology in humpback whales, we quantified baseline measurements of reproductive hormones (progesterone-P4, testosterone-T and 17ß-estradiol-E2) using an extensive archive of skin-blubber biopsy samples collected from female humpback whales in New Caledonia waters between 2016 and 2019 (n = 194). We observed significant differences in the P4, T and E2 concentrations across different demographic groups of female humpback whales, and we described some of the first evidence of the endocrine patterns of estrous in live free-ranging baleen whales. This study is fundamental in its methodological approach to a wild species that has a global distribution, with seasonally distinct life histories. This information will assist in monitoring, managing and conserving this population as global ecological changes continue to occur unhindered.

Blubber biopsy in common bottlenose dolphins using a novel biopsy puncher: Evaluation of the impact on living individuals and possibility of applications in cetacean research.

Biopsy has recently become a preferred protocol for sampling the skin and blubber of many cetacean species, although it is desirable to collect as minimally invasive as possible. Here, the effect of biopsy sampling on the captive common bottlenose dolphins was evaluated by analyzing the process of wound healing and changes in hematological and blood biochemical parameters after biopsy using a puncher developed to collect up to the inner layer of the dolphin blubber. Results showed that the wounds caused by biopsy were closed in as early as 1 day and completely covered with the epidermis within 5-11 days. Blood fibrinogen, which generally increases due to a wound-induced inflammatory response or activation of the coagulation system, was significantly elevated after the biopsy indicating ongoing tissue repair, while other parameters did not exhibit significant differences. Furthermore, histological observation and RNA extraction of samples were performed to investigate the versatility of this method to cetacean research. Histological examination revealed three distinct layers of the blubber in the biopsy samples. Moreover, total RNA extracted from biopsy samples exhibited sufficient quality and quantity for gene expression analyses. Overall, the puncher utilized in our study represents a valuable and minimally invasive tool for investigating various aspects of small cetacean studies.

Monk seals (Monachus monachus) in the Mediterranean Sea: The threat of organochlorine contaminants and polycyclic aromatic hydrocarbons.

The Mediterranean monk seal (Monachus monachus) is an emblematic species of conservation concern. Anthropogenic pressures have led to severe population declines and significant fragmentation of the remaining populations. Because of their close relationship with coastal areas, Mediterranean monk seals may be potentially exposed to pollution from agricultural sources, as well as from oil tanker spills. Although monitoring of pollution has long been considered a priority for this species, data on monk seal contamination levels are scarce. In this study, 55 blubber samples of all genders and age classes collected during necropsies (1995-2013) from seals of the Eastern Mediterranean subpopulation were analyzed for organochlorine compounds (OCs), i.e., hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDTs), and polycyclic aromatic hydrocarbons (PAHs). Overall, PCBs > DDTs ≫ PAHs > HCB in all samples. Results showed a significant downward trend over the 19-year period for DDTs and HCB. No marked pattern was found for PAHs, even though relative abundance of cancerogenic PAH fraction rose in recent years. PCB levels in subadult specimens increased noticeably over time despite worldwide ban. Our findings did not suggest recent releases of DDT or new pesticides (e.g., Dicofol) in the environment, but may indicate an improper disposal of ancient storages of PCBs or a remobilization from reservoirs. OC levels exceeded thresholds that are commonly associated with immunosuppression and reproductive impairment in other pinnipeds. Hence, OCs could be responsible of potential toxicological effects in this subpopulation. This study represents the first report on PAH and one of the few reports on OC bioaccumulation in Mediterranean monk seals. Based on the levels found in the blubber of monk seals from the Eastern Mediterranean, and given the known harmful effects associated to the prolonged exposure to these substances and the reduced long-term expectations of species recovery, regular monitoring is advocated.

Optimization and validation of a micro-QuEChERS method for phthalates detection in small samples of cetacean blubber.

In this study, an innovative method was developed to detect and quantify phthalates in fresh cetacean blubber. An adaptation of the ammonium formate QuEChERS method was used and adapted as a micro-extraction for small quantities of samples. Significantly, this technique utilized minimal quantities of reagents and salts, with the additional implementation of rigorous Quality Assurance/Quality Control protocols to further reduce background contamination. To ensure the reliability of this method, comprehensive validation procedures were conducted, with a specific focus on two widely studied cetacean species: the common bottlenose dolphin (Tursiops truncatus) and the short-finned pilot whale (Globicephala macrorhynchus). Determination coefficients (R2) for matrix-matched calibration were >0.93 with limits of quantifications (LOQ) of the method in the range of 5-10 ng/g. Mean recovery values were between 40 and 100 %. This novel methodology holds particular relevance for environmental research studies, offering the capability to detect emerging contaminants with minimal sample requirements. This aspect is particularly valuable in investigations that involve free-ranging animals and rely on biopsy sampling. It allows for the assessment of contaminant levels in healthy individuals within wild populations, enhancing our understanding of ecological impacts and potential conservation measures.•A micro-extraction adaptation of the ammonium formate QuEChERS method was developed and applied to a small quantity of fresh cetacean blubber to detect phthalates.•Small quantities of reagents and salts were used, and additional Quality Assurance/ Quality Control procedures were taken to further minimize background contamination.•Method validation was carried out for two cosmopolitan and extensively studied cetacean species: the common bottlenose dolphin (Tursiops truncatus) and the short-finned pilot whale (Globicephala macrorhynchus).

Varying Diet Composition Causes Striking Differences in Legacy and Emerging Contaminant Concentrations in Killer Whales across the North Atlantic.

Lipophilic persistent organic pollutants (POPs) tend to biomagnify in food chains, resulting in higher concentrations in species such as killer whales (Orcinus orca) feeding on marine mammals compared to those consuming fish. Advancements in dietary studies include the use of quantitative fatty acid signature analysis (QFASA) and differentiation of feeding habits within and between populations of North Atlantic (NA) killer whales. This comprehensive study assessed the concentrations of legacy and emerging POPs in 162 killer whales from across the NA. We report significantly higher mean levels of polychlorinated biphenyls (PCBs), organochlorine pesticides, and flame retardants in Western NA killer whales compared to those of Eastern NA conspecifics. Mean ∑PCBs ranged from ∼100 mg/kg lipid weight (lw) in the Western NA (Canadian Arctic, Eastern Canada) to ∼50 mg/kg lw in the mid-NA (Greenland, Iceland) to ∼10 mg/kg lw in the Eastern NA (Norway, Faroe Islands). The observed variations in contaminant levels were strongly correlated with diet composition across locations (inferred from QFASA), emphasizing that diet and not environmental variation in contaminant concentrations among locations is crucial in assessing contaminant-associated health risks in killer whales. These findings highlight the urgency for implementing enhanced measures to safely dispose of POP-contaminated waste, prevent further environmental contamination, and mitigate the release of newer and potentially harmful contaminants.

Estimating pregnancy rate from blubber progesterone levels of a blindly biopsied beluga population poses methodological, analytical and statistical challenges.

Beluga (Delphinapterus leucas) from the St. Lawrence Estuary, Canada, have been declining since the early 2000s, suggesting recruitment issues as a result of low fecundity, abnormal abortion rates or poor calf or juvenile survival. Pregnancy is difficult to observe in cetaceans, making the ground truthing of pregnancy estimates in wild individuals challenging. Blubber progesterone concentrations were contrasted among 62 SLE beluga with a known reproductive state (i.e. pregnant, resting, parturient and lactating females), that were found dead in 1997 to 2019. The suitability of a threshold obtained from decaying carcasses to assess reproductive state and pregnancy rate of freshly-dead or free-ranging and blindly-sampled beluga was examined using three statistical approaches and two data sets (135 freshly harvested carcasses in Nunavik, and 65 biopsy-sampled SLE beluga). Progesterone concentrations in decaying carcasses were considerably higher in known-pregnant (mean ± sd: 365 ± 244 ng g-1 of tissue) than resting (3.1 ± 4.5 ng g-1 of tissue) or lactating (38.4 ± 100 ng g-1 of tissue) females. An approach based on statistical mixtures of distributions and a logistic regression were compared to the commonly-used, fixed threshold approach (here, 100 ng g-1) for discriminating pregnant from non-pregnant females. The error rate for classifying individuals of known reproductive status was the lowest for the fixed threshold and logistic regression approaches, but the mixture approach required limited a priori knowledge for clustering individuals of unknown pregnancy status. Mismatches in assignations occurred at lipid content < 10% of sample weight. Our results emphasize the importance of reporting lipid contents and progesterone concentrations in both units (ng g-1 of tissue and ng g-1 of lipid) when sample mass is low. By highlighting ways to circumvent potential biases in field sampling associated with capturability of different segments of a population, this study also enhances the usefulness of the technique for estimating pregnancy rate of free-ranging population.

Effects of cortisol, epinephrine, and bisphenol contaminants on the transcriptional landscape of marine mammal blubber.

Top ocean predators such as marine mammals are threatened by intensifying anthropogenic activity, and understanding the combined effects of multiple stressors on their physiology is critical for conservation efforts. We investigated potential interactions between stress hormones and bisphenol contaminants in a model marine mammal, the northern elephant seal (NES). We exposed precision-cut adipose tissue slices (PCATS) from blubber of weaned NES pups to cortisol (CORT), epinephrine (EPI), bisphenol A (BPA), bisphenol S (BPS), or their combinations (CORT-EPI, BPA-EPI, and BPS-EPI) ex vivo and identified hundreds of genes that were differentially regulated in response to these treatments. CORT altered expression of genes associated with lipolysis and adipogenesis, whereas EPI and CORT-EPI-regulated genes were associated with responses to hormones, lipid and protein turnover, immune function, and transcriptional and epigenetic regulation of gene expression, suggesting that EPI has wide-ranging and prolonged impacts on the transcriptional landscape and function of blubber. Bisphenol treatments alone had a weak impact on gene expression compared with stress hormones. However, the combination of EPI with bisphenols altered expression of genes associated with inflammation, cell stress, DNA damage, regulation of nuclear hormone receptor activity, cell cycle, mitochondrial function, primary ciliogenesis, and lipid metabolism in blubber. Our results suggest that CORT, EPI, bisphenols, and their combinations impact cellular, immune, and metabolic homeostasis in marine mammal blubber, which may affect the ability of marine mammals to sustain prolonged fasting during reproduction and migration, renew tissues, and mount appropriate responses to immune challenges and additional stressors.

Trace elements and lipidomic datasets of stranding samples in the blubber of Turpsios truncatus from the Yucatan coast: Association with biological features.

The Yucatan coastal zone is an area that contributes to many anthropogenic activities resulting in substantial contamination (metals, pesticides) in aquatic organisms. The dolphin is an excellent sentinel animal used in studying contamination in this area. Some substances found in dolphins have been identified as toxic causing alterations in the properties of membranes and produce lipid peroxidation especially heavy metals. The dataset presented here is associated with the research article paper entitled "Trace element and lipidomic analysis of bottlenose dolphin blubber from the Yucatan coast: Lipid composition relationships". In this article, we presented the trace element concentrations found in blubber and their comparison with other studies performed in mammal marine organisms. Lipidomic characterization of bottlenose dolphin blubber and their association with trace elements and the differences related to biological characteristics were presented. This data provides a correlation analysis between trace element concentrations, lipid species and body length and the lipid differences related to biological characteristics such as growth stage, stranding code, and the presence of stomach contents. We used Spearman correlation analysis to identify the association with body length, trace elements and lipids. Wilcoxon rank-sum test was used to determine differences in lipids related to stranding code (3: moderate decomposition, 4: advanced decomposition), growth stage (juveniles and adults) and whether they showed presence of stomach contents or not. The data indicates that Cr, Cd and Zn concentrations were higher compared to concentrations found in blubbler of T. truncatus from other studies (See Table 3). Cr, Co, As and Cd were found in higher concentration in larger organisms compared to smaller ones. The results of correlation between lipids and body length showed a decrease in some ceramides (CER, DCER, HCER), sterols (CE), glycerolipids (TAG, DAG) and phosphatidylethanolamines (LPE, PE) in larger dolphins (Table 4). Dolphins with advanced decomposition (code 4) showed lower concentrations of phosphatidylethanolamines (PE) compared with organisms with moderate decomposition (code 3). Organisms with empty stomachs showed higher concentrations of phosphoethanolamines suggesting a preferential metabolism of energy-rich lipids over structural lipids. The information in these datasets may contribute to understanding the potential associations of trace elements, lipids and their associations with biological characteristics.

Hormonal biomarkers provide insights into the reproductive biology and pollutants-associated health hazards of endangered dolphins.

Contaminants are known to contribute to the reproductive health hazards of wildlife, but pollutants-associated detrimental impacts on the endangered Indo-Pacific humpback dolphins (Sousa chinensis, IPHD) are largely unknown due to a lack of reproductive parameters. Here we validated and applied blubber progesterone and testosterone as reproductive biomarkers to assess reproductive parameters of IPHD (n = 72). The gender-specific progesterone concentrations and progesterone/testosterone (P/T) supported progesterone and testosterone as valid biomarkers in identifying the genders of IPHD. Significant month-to-month variations of two hormones indicated a seasonal reproduction, in accordance with the observation of photo-identification approach, further supporting testosterone and progesterone as ideal reproductive biomarkers. Progesterone and testosterone concentrations showed significant differences between Lingding Bay and West-four region, possibly due to chronically geographic-specific pollutants differences. The significant relationships between sex hormones and multiple contaminants suggested that contaminants contribute to the disruption of testosterone and progesterone homeostasis. The best explanatory models between pollutants and hormones suggested that dichlorodiphenyltrichloroethanes (DDTs), lead (Pb) and selenium (Se) were the major risk factors jeopardizing the reproductive health of IPHD. This is the first study on the relationship between pollutant exposure and reproductive hormones in IPHD and represents a substantial advance in understanding the detrimental reproductive impacts of pollutants on endangered cetaceans.

Assessment of the presence of UV filters and UV stabilizers in stranded dolphin blubber.

The presence of ultraviolet filters (UVFs) and stabilizers (UVSs) was evaluated for the first time in the common bottlenose dolphin (Tursiops truncatus). UVFs and UVSs are compounds of growing concern because their effects on the environment are not completely known. UVFs and UVSs are added to personal care products (PCPs), such as cosmetics and products related to sun care and once released to the aquatic ecosystem, marine organisms can bioaccumulate these substances. This work aimed to determine the presence of 12 UVFs and UVSs in cetacean blubber samples to assess the pollution to which these animals of the highest trophic chain levels are exposed due to human activity. Analytical determinations were carried out using a method based on microwave-assisted extraction combined with ultrahigh-performance liquid chromatography and tandem mass spectrometry detection. The developed method was successfully applied to determine the target compounds in the blubber tissues of five necropsied common bottlenose dolphins. Three of the 12 studied compounds, namely 2-ethylhexyl 2-cyano-3,3-diphenylprop-2-enoate (octocrilene, OC), 2-hydroxy-4-methoxybenzophenone (benzophenone 3, BP3) and 3-methylbutyl (E)-3-(4methoxyphenyl) prop-2-enoate (IMC), were detected in several samples. Of the identified compounds, OC was present in all the samples and at the highest concentration within the range from 52.61 ± 18.59 to 108.0 ± 11.32 ng·g-1.

Quantitative fatty acid signature analysis reveals a high level of dietary specialization in killer whales across the North Atlantic.

Quantifying the diet composition of apex marine predators such as killer whales (Orcinus orca) is critical to assessing their food web impacts. Yet, with few exceptions, the feeding ecology of these apex predators remains poorly understood. Here, we use our newly validated quantitative fatty acid signature analysis (QFASA) approach on nearly 200 killer whales and over 900 potential prey to model their diets across the 5000 km span of the North Atlantic. Diet estimates show that killer whales mainly consume other whales in the western North Atlantic (Canadian Arctic, Eastern Canada), seals in the mid-North Atlantic (Greenland), and fish in the eastern North Atlantic (Iceland, Faroe Islands, Norway). Nonetheless, diet estimates also varied widely among individuals within most regions. This level of inter-individual feeding variation should be considered for future ecological studies focusing on killer whales in the North Atlantic and other oceans. These estimates reveal remarkable population- and individual-level variation in the trophic ecology of these killer whales, which can help to assess how their predation impacts community and ecosystem dynamics in changing North Atlantic marine ecosystems. This new approach provides researchers with an invaluable tool to study the feeding ecology of oceanic top predators.

Connaître en détails la composition du régime alimentaire des grands prédateurs marins tels que les orques (Orcinus orca) est primordial afin d'évaluer leurs impacts sur les écosystèmes. Pourtant, à quelques exceptions près, l'écologie alimentaire de ces super-prédateurs reste mal comprise. Ici, nous utilisons notre nouvelle approche d'analyse quantitative des signatures d'acides gras (QFASA) sur près de 200 orques et plus de 900 proies potentielles pour modéliser leur régime alimentaire à travers l'Atlantique Nord. Les estimations de leurs régimes alimentaires montrent que les orques consomment principalement d'autres baleines dans l'ouest de l'Atlantique Nord (Arctique canadien, Est du Canada), des phoques dans le milieu de l'Atlantique Nord (Groenland) et des poissons dans l'est de l'Atlantique Nord (Islande, îles Féroé, Norvège). Néanmoins, ces estimations varient considérablement d'un individu à l'autre dans la plupart des régions. Cette variation alimentaire importante entre les individus doit être prise en compte dans les futures études écologiques qui s'intéressent aux orques de l'Atlantique Nord et d'ailleurs. Ces estimations révèlent des variations remarquables dans l'écologie trophique des orques tant au niveau des population que de l'individu, ce qui peut aider à évaluer l'impact de leur prédation sur la dynamique des communautés et des écosystèmes dans un contexte de changements climatiques en l'Atlantique Nord. Cette nouvelle approche fournit aux chercheurs un outil inestimable pour étudier l'écologie alimentaire des super-prédateurs océaniques.

Variation in blubber thickness and histology metrics across the body topography of a false killer whale (Pseudorca crassidens).

Blubber is a multifunctional tissue essential to the survival of cetaceans. Histological assessment of blubber may be useful in determining odontocete nutritional state but a greater understanding of specific variation across the body is needed. We report on morphological variation of the blubber according to girth axes and sampling planes in a sub-adult male, bycaught false killer whale (Pseudorca crassidens) using metrics of blubber thickness (BT), adipocyte area (AA), and adipocyte index (AI). 48 full depth blubber samples were taken along 6 girth axes at 5 equidistant sampling points on both sides of the body. At these sampling locations BT was recorded, and AA and AI were determined for three distinct blubber layers. Linear mixed effect models were used to assess variation of the blubber across layers and body topography. BT was somewhat non-uniform across the body but was generally thicker in the dorsal region and thinner laterally. AA was greater cranially and AI was greater caudally. The middle and inner layer blubber showed significant differences dorsoventrally with larger AA and smaller AI in the ventral region of the body. Variation of the blubber metrics across the body are indicative of variable functions of the blubber within an individual. Due to the variability observed, we expect that AI of the dynamic inner layer blubber is most informative of overall body condition and that biopsy samples of the outer and middle blubber may still be useful in determining the nutritional status of live false killer whales.

The first full-congener analysis of 209 polychlorinated biphenyls (PCBs) in the blubber of short-finned pilot whales (Globicephala macrorhynchus) stranded along the coast of Savu Island, Indonesia.

Short-finned pilot whales (SFPW) are a group of cetaceans found globally in tropical and temperate seas and are commonly stranded in the group, but the reason behind their stranding is still unknown. No detailed information on the contamination status and bioaccumulation of halogenated organic compounds, including polychlorinated biphenyls (PCBs), in the SFPW from Indonesian waters has been reported. Therefore, we analyzed all 209 PCB congeners in the blubber of 20 SFPW specimens stranded along the coast of Savu Island, East Nusa Tenggara, Indonesia, in October 2012 to explain the status of contamination, congener profiles, potential risk of PCBs to cetaceans, and the determination of unintentionally produced PCBs (u-PCBs) in the blubber of SFPW. Concentrations of Σ209PCBs, Σ7in-PCBs, Σ12dl-PCBs, and Σ21u-PCBs were between 48 and 490 (mean:240 ± 140), 22-230 (110 ± 60), 2.6-38 (17 ± 10), and 1.0-13 (6.3 ± 3.7) ng g-1 lipid weight (lw), respectively. Congener-specific profiles of PCBs among sex and estimated age groups were observed; relatively high proportions of tri-to penta-CBs in juveniles and highly chlorinated recalcitrant congeners in structure-activity groups (SAGs) in sub-adult females were noted. The estimated toxic equivalency (TEQs) value for dl-PCBs ranged from 2.2 to 60 TEQWHO pg/g lw, with juveniles containing high TEQ values than sub-adults and adults. Although the TEQs and concentrations of PCBs in SFPW stranded along Indonesian coasts were lower than those reported for similar whale species from other North Pacific regions, further research is needed to assess the long-term impact of halogenated organic pollutants on their survival and health.

Variation of blubber thickness for three marine mammal species in the southern Baltic Sea.

Evaluating populational trends of health condition has become an important topic for marine mammal populations under the Marine Strategy Framework Directive (MSFD). In the Baltic Sea, under the recommendation of Helsinki Commission (HELCOM), efforts have been undertaken to use blubber thickness as an indicator of energy reserves in marine mammals. Current values lack geographical representation from the entire Baltic Sea area and a large dataset is only available for grey seals (Halichoerus grypus) from Sweden and Finland. Knowledge on variation of blubber thickness related to geography throughout the Baltic Sea is important for its usage as an indicator. Such evaluation can provide important information about the energy reserves, and hence, food availability. It is expected that methodological standardization under HELCOM should include relevant datasets with good geographical coverage that can also account for natural variability in the resident marine mammal populations. In this study, seasonal and temporal trends of blubber thickness were evaluated for three marine mammal species-harbor seal (Phoca vitulina), grey seal (Halichoerus grypus) and harbor porpoise (Phocoena phocoena)-resident in the southern Baltic Sea collected and investigated under stranding networks. Additionally, the effects of age, season and sex were analyzed. Seasonal variation of blubber thickness was evident for all species, with harbor seals presenting more pronounced effects in adults and grey seals and harbor porpoises presenting more pronounced effects in juveniles. For harbor seals and porpoises, fluctuations were present over the years included in the analysis. In the seal species, blubber thickness values were generally higher in males. In harbor seals and porpoises, blubber thickness values differed between the age classes: while adult harbor seals displayed thicker blubber layers than juveniles, the opposite was observed for harbor porpoises. Furthermore, while an important initial screening tool, blubber thickness assessment cannot be considered a valid methodology for overall health assessment in marine mammals and should be complemented with data on specific health parameters developed for each species.

Persistent organic pollutant exposure and associations with gene expression in northern fur seals (Callorhinus ursinus) from St. Paul Island, Alaska.

Persistent organic pollutants (POPs) are highly lipophilic compounds that accumulate at increased concentrations in high tropic level organisms like marine mammals. Marine mammals' reliance on blubber makes them susceptible to accumulating POPs at potentially toxic concentrations. In this study, we analyzed POP concentrations, (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and methoxylated-BDE (MeOBDE), in the blubber of 16 subsistence harvested sub-adult, male northern fur seals as well as assessed changes in mRNA gene expression of nine relevant biomarkers including the aryl hydrocarbon receptor, thyroid receptor-α, and adiponectin. PBDE and MeOBDE concentrations were significantly lower than PCB and OCP concentrations. A negative relationship was observed between percent lipid in the blubber and contaminant concentrations, both individual and sum. Expression changes in eight biomarkers were correlated with individual and sum contaminant concentrations. This study shows that contaminant concentrations measured are correlated to changes in expression of genes from different physiological systems, metabolism and endocrine, that are important for the regulation of blubber metabolism. Northern fur seals are reliant on blubber as an energy source during times of low food intake. Potential contaminant induced changes in blubber metabolism pathways could have significant impacts on the health of individuals during critical periods.

Spatiotemporal variation of ringed seal blubber cortisol levels in the Canadian Arctic.

Climate change in the Arctic has widespread and complex effects on the health of animals and their populations. We used radioimmunoassay to measure blubber cortisol in ringed seals (Pusa hispida) sampled in Ulukhaktok, Inuvialuit Settlement Region, Northwest Territories, Canada (spring, 2002, 2004-2005, 2007-2012) and Arviat, Nunavut, Canada (autumn, 2003-2012) to examine chronic stress relative to biology (age, sex, length), body condition (blubber depth), and diet (δ13C, δ15N, and isotopic niche size). Ulukhaktok ringed seals had higher cortisol concentrations overall (0.46 ± 0.04 ng/g) than Arviat ringed seals (0.36 ± 0.03 ng/g), and these higher concentrations were associated with higher muscle δ15N and lower blubber thickness. In contrast, blubber cortisol concentrations for Arviat ringed seals decreased with blubber depth and increased with age, though testing of age effects individually suggests that age-related patterns are weak. Annual mean cortisol concentration increased from 2003 to 2012 in Arviat ringed seals, but low sample sizes precluded analysis of annual patterns for Ulukhaktok ringed seals. The trend of increased cortisol over time in Arviat ringed seals suggests that they might be experiencing greater chronic stress over time, which could have implications for numerous population health metrics including reproduction and pup recruitment.

Functional Attenuation of UCP1 as the Potential Mechanism for a Thickened Blubber Layer in Cetaceans.

Uncoupling protein 1 (UCP1) is an essential protein in the mitochondrial inner membrane that mediates nonshivering thermogenesis (NST) and plays an important role in thermoregulation and fat deposition. However, the relationship between the evolution of UCP1 and fat deposition in the blubber layer in cetaceans remains unclear. Here, frameshift mutations, premature termination, and relaxed selection pressure (ω = 0.9557, P < 0.05) were detected in UCP1 in cetaceans, suggesting that UCP1 was inactivated during cetacean evolution. By time estimation, it was found that the inactivation of UCP1 in cetaceans occurred between 53.1 and 50.2 Ma. However, combined with findings from immunohistochemical analysis of the blubber layer of the Yangtze finless porpoise and in vitro functional assays, a premature termination of cetacean UCP1 resulted in a reduction of UCP1-mediated NST capacity (about 50%) and lipolytic capacity (about 40%), both of which were beneficial to maintain blubber layer and body temperature without excessive fat consumption. This study provides new insights into the molecular mechanisms of the blubber thickening in cetaceans and highlights the importance of UCP1 attenuation in cetaceans for secondary aquatic adaptation.