Contaminant blubber burdens in Atlantic bottlenose dolphins (Tursiops truncatus) from two southeastern US estuarine areas: concentrations and patterns of PCBs, pesticides, PBDEs, PFCs, and PAHs

PAHs in franciscana dolphins from the Southwestern Atlantic Ocean: Concentration and maternal transfer assessments

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds ubiquitous in the environment and known for their toxic, mutagenic, and carcinogenic effects. These compounds can bioaccumulate in the biota and be transferred through trophic webs. The franciscana dolphin (Pontoporia blainvillei), as top predators, can be an environmental sentinels. Thus, this study aimed to provide data about PAHs concentration in their hepatic tissue collected on the coast of Espírito Santo (Franciscana Management Area, FMA Ia), Rio de Janeiro (FMA IIa), and São Paulo states (FMA IIb), in Southeastern Brazil. PAHs were detected in 86 % of franciscana dolphins (n = 50). The highest ∑PAHsTotal median concentration was reported in FMA Ia followed by FMA IIb and FMA IIa (1055.6; 523.9, and 72.1 ng.g-1 lipid weight, respectively). Phenanthrene was detected in one fetus and two neonates, showing maternal transfer of PAHs in these dolphins. Evaluating PAHs with potential toxic effects is of utmost importance for the conservation of a threatened species.

Investigation of the Link between Per- and Polyfluoroalkyl Substances and Stress Biomarkers in Bottlenose Dolphins (Tursiops truncatus)

Bottlenose dolphins (Tursiops truncatus) are keystone and sentinel species in the world's oceans. We studied correlations between per- and polyfluoroalkyl substances (PFAS) and their stress axis. We investigated associations between plasma biomarkers of 12 different PFAS variants and three cortisol pools (total, bound, and free) in wild T. truncatus from estuarine waters of Charleston, South Carolina (n = 115) and Indian River Lagoon, Florida (n = 178) from 2003 to 2006, 2010-2013, and 2015. All PFAS and total cortisol levels for these dolphins were previously reported; bound cortisol levels and free cortisol calculations have not been previously reported. We tested null hypotheses that levels of each PFAS were not correlated with those of each cortisol pool. Free cortisol levels were lower when PFOS, PFOA, and PFHxS biomarker levels were higher, but free cortisol levels were higher when PFTriA was higher. Bound cortisol levels were higher when there were higher PFDA, PFDoDA, PFDS, PFTeA, and PFUnDA biomarkers. Total cortisol was higher when PFOA was lower, but total cortisol was higher when PFDA, PFDoDA, PFTeA, and PFTriA were higher. Additional analyses indicated sex and age trends, as well as heterogeneity of effects from the covariates carbon chain length and PFAS class. Although this is a cross-sectional observational study and, therefore, could reflect cortisol impacts on PFAS toxicokinetics, these correlations are suggestive that PFAS impacts the stress axis in T. truncatus. However, if PFAS do impact the stress axis of dolphins, it is specific to the chemical structure, and could affect the individual pools of cortisol differently. It is critical to conduct long-term studies on these dolphins and to compare them to populations that have no or little expose to PFAS.

Persistent organic pollutants and polycyclic aromatic hydrocarbons in livers of stranded Arctocephalus australis in southern Brazilian beaches

23 livers of South American fur seal (Arctocephalus australis) found stranded in southern Brazilian beaches were evaluated for Persistent Organic Pollutants (POPs) and Polycyclic Aromatic Hydrocarbons (PAHs). POPs (DDTs, mirex, eldrin, dieldrin, aldrin, isodrin, HCHs, chlordanes and PCBs) and PAHs in livers were Soxhlet extracted, analyzed and quantified using Gas Chromatography Tandem Mass Spectrometry (GC-TQMS). The main POPs found were PCBs and DDTs, totaling 81 %. Among pesticides, mirex followed DDTs, possibly due to usage in Uruguay, followed by Σdrins, ΣCHLs and ΣHCHs. Naphthalene was the major PAH found, while heavier compounds did not significantly bioaccumulate. Concentrations of POPs resembled previous findings for A. australis. Considering only juveniles, no POPs showed significant differences between sexes. Lipidic content, weight and length did not show any correlation with POP concentration. This was the first record of PAHs and PBDEs in South American fur seals, and the levels of these pollutants were relatively low.

Legacy and emerging contaminants in marine mammals from Argentina

Marine mammals are recognized sentinels of ecosystem health. They are susceptible to the accumulation and biomagnification of pollutants, which constitute one of the greatest threats to their survival. Legacy, such as organochlorine pesticides, and emerging contaminants, like microplastics and pharmaceuticals, may have effects on marine mammals' health at individual and population levels. Therefore, the evaluation of the risks associated with pollutants in this group is of great importance. The aim of this review is to provide information on the occurrence of legacy and emerging contaminants in marine mammals that inhabit Argentine waters. Also, to identify knowledge gaps and suggest best practices for future research. Reports of legacy contaminants referring to organochlorine pesticides and polychlorinated biphenyls were found in five species of cetaceans and two of pinnipeds. With respect to emerging pollutants, the presence of plastics was only evaluated in three species. Reported data was from at least a decade ago. Therefore, it is necessary to update existing information and conduct continuous monitoring to assess temporary trends in pollutants. All the studies were carried out in the province of Buenos Aires and Northern Patagonia indicating a knowledge gap in the southern zone of the Argentine Sea. In addition, pollutants of global environmental concern that have not been studied in Argentina are discussed. Future studies should fill these gaps and a greater effort to understand the relationships between pollutants and their effects on marine mammals is suggested. This issue will make it possible to determine thresholds for all the substances and species evaluated in order to carry out more detailed risk assessments and make decisions for the conservation of marine mammals in Argentine waters.

Polycyclic aromatic hydrocarbon (PAH) source identification and a maternal transfer case study in threatened killer whales (Orcinus orca) of British Columbia, Canada

The northeastern Pacific (NEP) Ocean spans the coast of British Columbia (Canada) and is impacted by anthropogenic activities including oil pipeline developments, maritime fossil fuel tanker traffic, industrial chemical effluents, agricultural and urban emissions in tandem with stormwater and wastewater discharges, and forest wildfires. Such events may expose surrounding marine environments to toxic polycyclic aromatic hydrocarbons (PAHs) and impact critical habitats of threatened killer whales (Orcinus orca). We analyzed skeletal muscle and liver samples from stranded Bigg's killer whales and endangered Southern Resident killer whales (SRKWs) for PAH contamination using LRMS. C3-phenanthrenes/anthracenes (mean: 632 ng/g lw), C4-dibenzothiophenes (mean: 334 ng/g lw), and C4-phenanthrenes/anthracenes (mean: 248 ng/g lw) presented the highest concentrations across all tissue samples. Diagnostic ratios indicated petrogenic-sourced contamination for SRKWs and pyrogenic-sourced burdens for Bigg's killer whales; differences between ecotypes may be attributed to habitat range, prey selection, and metabolism. A mother-fetus skeletal muscle pair provided evidence of PAH maternal transfer; low molecular weight compounds C3-fluorenes, dibenzothiophene, and naphthalene showed efficient and preferential exposure to the fetus. This indicates in-utero exposure of PAH-contamination to the fetus. Our results show that hydrocarbon-related anthropogenic activities are negatively impacting these top predators; preliminary data found here can be used to improve oil spill and other PAH pollution management and regulation efforts, and inform policy to conserve killer whale habitats in the NEP.

Discussion. Has the human population become a sentinel for the adverse effects of PFAS contamination on wildlife health and endangered species?

Global contamination with per- and polyfluoroalkyl substances (PFAS) poses a threat to both human health and the environment, with significant implications for ecological conservation policies. A growing list of peer-reviewed publications indicates that PFAS can harm wildlife health and that the adverse effects associated with PFAS exposure in wildlife are in concordance with human epidemiological studies. The correlation of cross-species data supports a unique perspective that humans can be regarded as a sentinel for PFAS effects in other species. The health harms due to PFAS are potentially most concerning for populations of endangered and threatened species that are simultaneously exposed to PFAS and other toxic pollutants, and also face threats to their survival due to habitat loss, degradation of ecosystems, and over-harvesting. Human epidemiological studies on the PFAS doses associated with health harm present a rich source of information about potential impacts on wildlife health due to PFAS. Our analysis suggests that national and international efforts to restrict the discharges of PFAS into the environment and to clean up PFAS-contaminated sites present an opportunity to protect wildlife from chemical pollution and to advance species conservation worldwide.

A systematic review of the diversity and virulence correlates of metastrongyle lungworms in marine mammals

Metastrongyle lungworms could be particularly detrimental for diving animals such as marine mammals; however, little is known of the drivers of pathogenic host–parasite relationships in this group. This systematic review analysed the diversity of metastrongyles in marine mammals and the host and parasite traits associated with virulence. There have been at least 40 species of metastrongyles described in 66 species of marine mammals. After penalization for study biases, Halocercus hyperoodoni, Otostrongylus circumlitus, Parafilaroides gymnurus, Halocercus brasiliensis and Stenurus minor were the metastrongyles with the widest host range. Most studies (80.12%, n = 133/166) reported that metastrongyles caused bronchopneumonia, while in the cardiovascular system metastrongyles caused vasculitis in nearly half of the studies (45.45%, n = 5/11) that assessed these tissues. Metastrongyles were associated with otitis in 23.08% (n = 6/26) of the studies. Metastrongyle infection was considered a potential contributory to mortality in 44.78% (n = 90/201) of the studies while 10.45% (n = 21/201) of these studies considered metastrongyles the main cause of death. Metastrongyle species with a wider host range were more likely to induce pathogenic effects. Metastrongyles can cause significant tissue damage and mortality in marine mammals although virulent host–parasite relationships are dominated by a few metastrongyle species with wider host ranges.

Identification of Mid-Polar and Polar AhR Agonists in Cetaceans from Korean Coastal Waters: Application of Effect-Directed Analysis with Full-Scan Screening

Major aryl hydrocarbon receptor (AhR) agonists were identified in extracts of blubber, liver, and muscle from six long-beaked common dolphins (Delphinus capensis) and one fin whale (Balaenoptera physalus) collected from Korean coastal waters using effect-directed analysis. Results of the H4IIE-luc bioassay indicated that the polar fractions of blubber and liver extracts from the fin whale exhibited relatively high AhR-mediated potencies. Based on full-scan screening with high-resolution mass spectrometry, 37 AhR agonist candidates, spanning four use categories: pharmaceuticals, pesticides, cosmetics, and natural products, were selected. Among these, five polar AhR agonists were newly identified through toxicological confirmation. Concentrations of polar AhR agonists in cetaceans were tissue-specific, with extracts of blubber and liver containing greater concentrations than muscle extracts. Polar AhR agonists with great log KOA values (>5) were found to biomagnify in the marine food chain potentially. Polar AhR agonists contributed 8.9% of the observed AhR-mediated potencies in blubber and 49% in liver. Rutaecarpine and alantolactone contributed significantly to the total AhR-mediated potencies of blubber, whereas hydrocortisone was a major AhR contributor in the liver of the fin whale. This study is the first to identify the tissue-specific accumulation of polar AhR agonists in blubber and liver extracts of cetaceans.

Regional variation of polybrominated diphenyl ethers in East Asian finless porpoises in the East China Sea

Certain polybrominated diphenyl ethers (PBDEs) have been banned for years, however, they still possess the potential to harm marine cetaceans. In this study, 56 East Asian finless porpoises (EAFPs) collected from three locations of the East China Sea between 2009 and 2011, were analyzed to determine the presence of typical PBDE congeners. Among all the samples, BDE47 was the main congener, constituting ∼48.3 % of the ΣPBDEs. Significant variations (p < 0.01) in PBDE abundance were observed among different regions (Pingtan: 172.8 ng/g, Lvsi: 61.2 ng/g and Ningbo: 32.9 ng/g). In addition, there was a significant positive correlation between PBDE abundance and male body length. The general ΣPBDEs concentration of this population was lower compared to other populations and cetaceans. Although combined risk assessments indicated a low risk to porpoise health, long-term surveillance is essential as PBDEs are not completely banned.

Assessment of polycyclic aromatic hydrocarbons (PAHs) in mediterranean top marine predators stranded in SE Spain

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. Although they are not bioaccumulated in vertebrates, chronic exposures might still derive on serious toxic effects. We studied concentrations of 16 reference PAHs on blubber of two dolphin species (striped dolphin, n = 34; and bottlenose dolphin, n = 8) and one marine turtle (loggerhead turtle, n = 23) from the Mediterranean waters of SE Spain, an important or potential breeding area for these and other related species. Σ16 PAHs concentrations were relatively similar between the three species, but they were in the lower range in comparison to worldwide data. Of the six PAHs detected, fluoranthene was the only high molecular weight (HMW) PAH, so low molecular weight (LMW) PAHs predominated. Naphthalene and phenanthrene were invariably those PAHs with higher detection rates as well as those with higher concentrations. In accordance with the literature, sex and length did not have significant influence on PAHs concentrations, probably due to high metabolization rates which prevent for observation of such patterns. Despite LMW PAHs are considered less toxic, we cannot dismiss toxic effects. This is the first work assessing PAHs concentrations in cetaceans and sea turtles from the SE Spain, which could serve as the baseline for future research.

Occurrence and distribution of PAHs in stranded dolphin tissues from the Northwestern Mediterranean

There are few cetacean tissue-specific polycyclic aromatic hydrocarbon (PAH) concentration studies in the Mediterranean, despite this region is among the most subjected to chemical contamination. PAH analyses were conducted in different tissues of striped dolphins (Stenella coeruleoalba, N = 64) and bottlenose dolphins (Tursiops truncatus, N = 9) stranded along the French Mediterranean coastline from 2010 to 2016. Comparable levels were measured in S. coeruleoalba and T. trucantus (1020 and 981 ng g^-1 lipid weight in blubber, 228 and 238 ng g^-1 dry weight in muscle, respectively). The results suggested a slight effect of maternal transfer. The greatest levels were recorded by urban and industrial centers, and decreasing temporal trends were observed in males muscle and kidney, but not in other tissues. As a conclusion, the elevated levels measured could represent a serious threat to dolphins populations in this region, particularly by urban and industrial centers.

POPs concentrations in cetaceans stranded along the agricultural coastline of SE Spain show lower burdens of industrial pollutants in comparison to other Mediterranean cetaceans

Despite the Mediterranean Sea being one of the world's marine biodiversity hotspots, it is a hotspot of various environmental pollutants. This sea holds eight cetacean with resident populations whose numbers are considered to decline in the last decades and which are particularly susceptible to POPs bioaccumulation due to their peculiar characteristics. In this work, we studied blubber concentration of various OCPs and several PCBs and PBDEs congeners in cetaceans stranded in the northern coast of the Gulf of Vera (Region of Murcia, SE Spain) between 2011 and 2018. Most compounds and congeners were above the limit of detection in most samples, although some pesticides like endosulfan stereoisomers or endrin were never detected. DDT and its metabolites, PCBs and metoxychlor appear as the dominant compounds while PBDEs shows concentrations of lower magnitude. Striped dolphin was the species accounting for higher concentrations of most pollutants. There were differences in concentrations and profiles between species which could be partially explained by differences on diet and feeding behavior. We also observed differences based on life history parameters suggesting maternal transfer for most POPs, in accordance with other works. DDE/ ΣDDT ratio suggest no recent exposure to these pesticides. Despite showing lower concentrations than some previous works, PCB concentrations accounted for higher total TEQ than many studies. According to toxicity thresholds in the literature, we cannot guarantee the absence of health consequences on populations studied, especially for those caused by PCBs. These findings are of major importance considering the relevance of the study area in the conservation of Mediterranean cetaceans.

Long-Term Monitoring of Polybrominated Diphenyl Ethers (PBDEs) in Indo-Pacific Humpback Dolphins (Sousa chinensis) from the Pearl River Estuary Reveals High Risks for Calves due to Maternal Exposure

Although many studies have documented the wide occurrence of polybrominated diphenyl ethers (PBDEs) in cetaceans, little evidence exists regarding the detrimental effects of PBDE exposure on calf death rates for free-ranging cetaceans. This study analyzed life-history-associated PBDE bioaccumulation patterns in 128 stranding Indo-Pacific humpback dolphin (Sousa chinensis) samples over an 18-year timespan from the Pearl River Estuary (PRE). In comparison to the records of PBDE levels in cetaceans worldwide, the median levels of PBDEs (median = 10600 ng g^-1 lw, range = 721-50900 ng g^-1 lw) in all samples were the highest to date. One-way analysis of variance (ANOVA) showed that adult males (median = 16100 ng g^-1 lw, range = 4070-50900 ng g^-1 lw) and calves (12000 ng g^-1 lw, range = 1250-35300 ng g^-1 lw) both had the highest levels of PBDEs compared to the rest of the age/sex groups (p < 0.05). Concentrations of PBDEs in noncalves significantly decreased over the studied period, while those in calves had a slightly increasing trend, which may be due to different exposure routes via fish or milk, respectively. A significant and positive relationship was found between annual calf stranding death rates and body-length-adjusted PBDE concentrations in calves (r = 0.62, p < 0.05), suggesting that maternal exposure of calves to elevated levels of PBDEs may have contributed to the high annual stranding death rates of calves in the last two decades.

Pollution of water in Africa: a review of contaminants and fish as biomonitors and analytical methodologies-the case of Senegal

Environmental pollution is one of the major problems facing human health, ecosystems, and biodiversity. This is particularly the case for water quality in Senegal. Fish can be used as a biomonitor of pollution by accumulating pollutants from the environment through their tissues. Fish is an indispensable element in the assessment of the quality of the environment due to the diversity of biological cycles and their position in the food chain. Fish, which is very sensitive to chemical and bacterial pollution, concentrates pollutants and is a good indicator of water quality. This review presents water pollution in Senegal and the possibility of using fish as an ideal monitoring matrix for marine environments, to detect the concentration of heavy metals and organic pollutants. The different extraction and analytical techniques used for fish biomonitoring will be also described.

Trace Elements and Contaminants Concentrations in Tissues of Caspian Seals (Pusa caspica) along the Iranian Coast

The Caspian seal (Pusa caspica) is an endangered species that only lives in the Caspian Sea. Little information is available on its exposure to contaminants, and no data exists for Southern sub-populations. From 2011 to 2016, tissues samples were collected from 20 Caspian seals to (i) Define the concentration of trace elements in five different matrices and the concentration of 30 pesticides in their blubber; (ii) Determine whether differences in contaminant concentrations are age- or sex-related; (iii) Evaluate if detected concentrations can represent a risk to the species. Age- and sex-related variations were detected for Zn and Hg in the blubber and Fe in the kidney by age only. Exceptionally high Hg concentrations and low levels of hepatic Zn were detected, raising some concern about the reproductive health of seals. Similarly, the DDTs levels detected were in the range of adverse reproductive effects in marine mammals. Based on these results, potentially adverse effects on the immune and endocrine systems of the Caspian seal cannot be ruled out. Therefore, it is of the utmost importance that pollutant monitoring becomes an integral component of conservation strategies for the Caspian seal.

Cell cycle alterations due to perfluoroalkyl substances PFOS, PFOA, PFBS, PFBA and the new PFAS C6O4 on bottlenose dolphin (Tursiops truncatus) skin cell

Per- and polyfluoroalkyl substances (PFAS) have become ubiquitous environmental contaminants in aquatic ecosystems worldwide. Marine mammals, as top predators, are constantly exposed to several PFAS compounds that accumulate in different tissues. As a proxy to assess cytotoxicity of PFAS in the bottlenose dolphin (Tursiops truncatus), we generated a new immortalized cell line derived from skin samples of bottlenose dolphin. Using high content imaging, we assessed the effects of increasing concentrations of PFOS, PFOA, PFBS, PFBA and C6O4 on cell viability and cell cycle phases. In particular, we classified all cells based on multiple morphometric differences of the nucleus in three populations, named respectively "Normal" (nuclei in G0, S and M phase); "Large" (nuclei showing characteristics of senescence) and "Small" (nuclei with fragmentation and condensed chromatin). Combining this approach with cell cycle analysis we determined which phases of the cell cycle were influenced by PFAS. The results revealed that the presence of PFOS, PFBS and PFBA could increase the number of cells in G0+G1 phase and decrease the number of those in the S phase. Moreover, PFOS and PFBS lowered the fraction of cells in the M phase. Interestingly PFOS, PFBS and PFBA reduced the prevalence of the senescence phenotype ("large" nuclei), suggesting a potential tumorigenic effect. Besides, the presence of PFOS and PFBS correlated also with a significant decrease in the number of "small" nuclei. The C6O4 exposure did not highlighted morphometric alteration or cell cycle modification bottlenose dolphin skin cell nuclei. While the effects of PFAS on cell cycle was clear, no significant change was detected either in term of cell proliferation or of viability. This study fosters the overall knowledge on the cellular effects of perfluoroalkyl substances in marine mammals.

Polycyclic aromatic hydrocarbons in marine mammals: A review and synthesis

Most marine mammal species and populations are listed as endangered, threatened, or depleted under the Endangered Species Act and the Marine Mammal Protection Act. Organic contaminants such as polycyclic aromatic hydrocarbons from anthropogenic activities are part of the threat to marine mammals. The evaluation of the potential bioaccumulation of these compounds by marine mammals is a tool for adoption of policies to reduce polycyclic aromatic hydrocarbons discharges to the marine environment, where important players such as the oil and gas industries, maritime transport and sewage companies operate. This review seeks to present a bibliographic survey covering all published peer reviewed works of the contents of polycyclic aromatic hydrocarbons in biological tissues of marine mammals. It intended to compare the sampling protocols, procedures for preservation of the tissues, and the analytical method applied to quantify the polycyclic aromatic hydrocarbons, no to criticize any of them but to review the data and discuss how they can be compared.

EVALUATION OF IMMUNE FUNCTION IN TWO POPULATIONS OF GREEN SEA TURTLES (CHELONIA MYDAS) IN A DEGRADED VERSUS A NONDEGRADED HABITAT

There is a strong correlation between degraded marine habitats and the prevalence of diseases such as green turtle fibropapillomatosis (GTFP) in coastal populations. In GTFP, small to large tumors grow on the turtle's soft tissues and shell, while internal nodules may also occur. The disease primarily affects juvenile green sea turtles (Chelonia mydas) that reside in nearshore waters. As a link has been shown between environmental pollution and immune suppression in a variety of animals, the objective of our research was to compare innate and adaptive immune responsiveness in green sea turtles from a severely degraded and a more pristine habitat, which differ greatly in rates of GTFP. We quantified phagocytosis by flow cytometry and performed in vitro stimulation analysis to measure activity of both the innate and adaptive immune systems in wild-caught Florida green turtles. Sea turtles from the degraded environment, both with and without visible cutaneous tumors, exhibited significantly reduced phagocytosis and stimulation indices than did those from the less polluted environment. Our results suggest that environmental factors may contribute to the development of GTFP and thus can impact the health of sea turtle populations.

Circulating concentrations of thyroid hormones and cortisol in wild and semi-natural Yangtze finless porpoise (Neophocaena asiaeorientalis)

Our understanding about how environmental and biological variables may influence circulating thyroid and adrenal hormones in free-ranging cetaceans is limited. As such, we used liquid chromatography-mass spectrometry to determine concentrations of circulating cortisol and thyroid hormones (THs; tT3, tT4) in 132 Yangtze finless porpoises (YFPs) located in Poyang Lake, (PL, n = 92) and Tian-E-Zhou Oxbow reserve (TZO, n = 40). For overall hormone comparisons, animals were partitioned by age [juvenile and adult (male and non-pregnant, non-lactating female)], sex, season (winter or spring) and geographical location. Geographically, during winter, circulating THs were significantly higher in the PL versus TZO population. Seasonally, within PL, THs were significantly higher in the winter versus spring season. Animals were further binned into groups as follows: juvenile male (JM) and juvenile female (JF), adult male (AM), non-pregnant adult female, pregnant female and non-pregnant lactating female. Intra-group comparisons between locations showed a significant increase in JM THs at PL. Significant increases in THs during winter compared to spring were detected between JM and JF groups. Mean comparisons of cortisol within and between locations for each group identified a significant increase for TZO AM versus TZO pregnant female and JM and JF. Seasonally, in PL, only JF has significantly higher cortisol in winter versus spring. Finally, we established reference values of THs and cortisol for YFPs in different geographical locations. These references are important baselines from which the effects of environmental and biological variables on THs and cortisol may be evaluated.

Demographic Assessment of Mono(2-ethylhexyl) Phthalate (MEHP) and Monoethyl Phthalate (MEP) Concentrations in Common Bottlenose Dolphins (Tursiops truncatus) From Sarasota Bay, FL, USA

Common bottlenose dolphins (Tursiops truncatus) have previously demonstrated exposure to phthalate esters. Phthalates and phthalate esters are commonly added to consumer goods to enhance desirable properties. As the amount of plastic marine debris increases, these chemicals can easily leach from these products into the surrounding environment. To evaluate demographic variability in exposure, eight phthalate metabolites were quantified in urine samples collected from free-ranging bottlenose dolphins sampled in Sarasota Bay, FL, USA (2010-2019; n = 51). Approximately 75% of individual dolphins had detectable concentrations of at least one phthalate metabolite. The most frequently detected metabolites were mono(2-ethylhexyl) phthalate (MEHP; n = 28; GM = 4.57 ng/mL; 95% CI = 2.37-8.80; KM mean = 7.95; s.d. = 15.88) and monoethyl phthalate (MEP; GM = 4.51 ng/mL; 95% CI = 2.77-7.34; ROS mean = 2.24; s.d. = 5.58). Urinary concentrations of MEHP and MEP were not significantly different between sex (MEHP p = 0.09; MEP p = 0.22) or age class (i.e., calf/juvenile vs. adult; MEHP p = 0.67; MEP p = 0.13). Additionally, there were no significant group differences in the likelihood of MEHP or MEP detection for any demographic as determined by a Peto-Peto test. Frequency of detection was similar for both metabolites between males and females (MEHP p = 0.10; MEP p = 0.40) as well as between juveniles and adults (MEHP p = 0.50; MEP: p = 0.60). These findings suggest ubiquitous exposure risk for both sexes and age classes, warranting further investigation into potential sources and health implications.

Effects of an environmentally relevant PCB-mixture on immune function, clinical chemistry, and thyroid hormone levels in adult female B6C3F1 mice

Polychlorinated biphenyls (PCBs) have been assessed for immunotoxicity; however, humans and wildlife are exposed to multiple PCBs environmentally. Therefore, the aim of this study was to examine the effects of a complex 37 PCB congener mixture identified in blubber specific to dolphins residing in the estuarine waters of Charleston, South Carolina. Immunotoxicity was determined in adult female B₆C₃F₁ mice by assessing lymphocyte proliferation, splenic and thymic immunophenotypes, and IgM production. Mice were exposed via oral gavage to the PCB-mixture (0, 1.8, 3.6, 7.1, or 14.3 mg/kg/day) for 28 days to yield a targeted total administered dose (TAD) 0, 50, 100, 200, or 400 mg/kg. Significant increased liver weight occurred at the highest treatment. IgM production was suppressed compared to control for all treatments. Numbers of thymic CD4+/CD8+, CD4-/CD8-, and CD4+/CD8- cells were not altered, but numbers of thymic CD4-/CD8+ cells were significantly increased in the highest treatment. Lymphocyte proliferation was not markedly affected by any treatment. The numbers of splenic CD4/CD8 T-cells or MHCII+ cells were not significantly changed. Humoral immunity using the plaque-forming cell assay for determining the specific IgM antibody-forming cell response appeared to be the most sensitive endpoint affected. As the lowest concentration tested resulted in decreased IgM production and total and free thyroxine (T₄) serum levels a NOAEL was not identified. The calculated ED₅₀ for suppression of IgM production was 2.4 mg/kg/day.

Unintentionally produced polychlorinated biphenyls in pigments: An updated review on their formation, emission sources, contamination status, and toxic effects

The formation, emission, environmental occurrence, and potential adverse effects of unintentionally produced polychlorinated biphenyls (PCBs) in pigments are reviewed, providing a comprehensive and up-to-date picture on these pollutants. PCBs are typically formed during manufacturing of organic pigments that involve chlorinated intermediates and reaction solvents, rather than those of inorganic pigments. Concentrations and profiles of PCBs vary greatly among pigment types and producers, with total PCB levels ranging from lower than detection limits to several hundred ppm; major components can be low-chlorinated (e.g., CB-11) or high-chlorinated congeners (e.g., CB-209). Pigment-derived PCBs can be released into the environment through different steps including pigment production, application, and disposal. They can contaminate atmospheric, terrestrial, and aquatic ecosystems, and then affect organisms living there. This situation garners scientific and public attention to nonlegacy emissions of PCBs and suggests the need for appropriate monitoring, management, and abatement strategies regarding these pollutants.

First assessment of POPs and cytochrome P450 expression in Cuvier's beaked whales (Ziphius cavirostris) skin biopsies from the Mediterranean Sea

The Cuvier's beaked whale (Ziphius cavirostris) is one of the least known cetacean species worldwide. The decreasing population trend and associated threats has led to the IUCN categorising the Mediterranean subpopulation as Vulnerable on the Red List of Threatened Species. This study aimed to investigate for the first time the ecotoxicological status of Cuvier's beaked whale in the NW Mediterranean Sea. The study sampled around the 20% of the individuals belonging to the Ligurian subpopulation, collecting skin biopsies from free-ranging specimens. The levels of polychlorinated biphenyl (PCBs), polybrominated diphenyl ethers (PBDEs) and induction of cytochrome's P450 (CYP1A1 and CYP2B isoforms) were evaluated. Results highlighted that the pattern of concentration for the target contaminants was PCBs > PBDEs and the accumulation values were linked to age and sex, with adult males showing significantly higher levels than juvenile. Concerns raised by the fact that 80% of the individuals had PCB levels above the toxicity threshold for negative physiological effects in marine mammals. Therefore, these findings shed light on this silent and serious threat never assessed in the Mediterranean Cuvier’s beaked whale population, indicating that anthropogenic pressures, including chemical pollution, may represent menaces for the conservation of this species in the Mediterranean Sea.

Bio-accumulation of organic contaminants in Indo-Pacific humpback dolphins: Preliminary unique features of the brain and testes

There is little information about the residue levels and congener composition of organic contaminants (OCs) in cetaceans. In the present study, we investigated the polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the blubber, blood, brain and testes of Indo-Pacific humpback dolphins (Sousa chinensis) stranded in the Pearl River Estuary (PRE), China. The lowest blubber/tissue partition coefficients were found for sum hexachlorocyclohexanes (ΣHCHs) and ΣPAHs, while the highest were in ΣPCBs and sum dichlorodiphenyltrichloroethanes (ΣDDTs), likely attributing to the octanol-water partition features. The low levels of OCs in brain and testes theoretically resulted from the blood-brain barrier, blood-testes barrier, contaminant molecule dimensions and unique lipid compositions in the brain and testes. Compared with other contaminants, the higher mean brain/blood and testes/blood partition coefficients found for mirex, heptachlor, dieldrin and endrin would increase the risks associated with exposure-related toxicity and the bioavailability of contaminants within these tissues. Observations also suggest that as lipid mobilizes from blubber, contaminants may redistribute, leading to elevated tissue (such as brain) concentrations. Therefore, dolphins with less blubber may be more susceptible to health risks. The Indo-Pacific humpback dolphins living in PRE are at great risk due to variety of OCs in indirect contact with non-target organisms, affecting the health of animals (toxic effects and accumulation). Our findings contribute to the knowledge of the potential effects of OCs exposure on developmental neurotoxicity and reproductive damage in marine mammals.

Perfluoroheptanoic acid induces Leydig cell hyperplasia but inhibits spermatogenesis in rats after pubertal exposure

Perfluoroheptanoic acid (PFHpA) is a short-chain alternative to long-chain perfluoroalkyl substances, which have been reported to possess reproductive toxicity. However, it is unclear whether PFHpA affects Leydig cell development during puberty. The 35-day-old Sprague Dawley male rats were exposed to PFHpA by gavage with 0 (corn oil), 10, 50, and 100 mg/kg/day for 21 days. PFHpA did not affect the body weight of rats, but it reduced testis weight, relative testis weight, and epididymis weight at 100 mg/kg. It significantly increased serum testosterone, luteinizing hormone, and follicle-stimulating hormone levels at a dose of 100 mg/kg without affecting serum estradiol levels. PFHpA suppressed sperm production at a dose of 100 mg/kg. PFHpA induced Leydig cell hyperplasia (increased number of CYP11A1-positive Leydig cells) at a dose of 100 mg/kg, but down-regulated the expression of Cyp11a1, Hsd3b1, and Cyp17a1 in individual Leydig cell pe se and up-regulated the expression of Fshr in the Sertoli cell pe se. PFHpA did not affect the number of HSD11B1 (a biomarker for more mature Leydig cells) positive Leydig cells and SOX9 positive Sertoli cells. PFHpA increased BCL2, and the phosphorylation of AKT1, AKT2, ERK1/2, and JNK, but decreased BAX levels. However, it had no effect on SIRT1 and PGC-1α levels. In conclusion, PFHpA induces Leydig cell hyperplasia due to the increase in the secretion of luteinizing hormone through negative feedback after down-regulating the expression of steroidogenic enzymes and inhibiting testosterone production in individual Leydig cells. This proliferation may be mediated by increasing BCL2 and phosphorylation of AKT, ERK1/2, and JNK, and decreasing BAX level.

First report from North America of microplastics in the gastrointestinal tract of stranded bottlenose dolphins (Tursiops truncatus)

Microplastics' (MPs) abundance, small size, and global distribution render them bioavailable to a variety of organisms directly or by trophic transfer, yet examinations in marine apex predators are currently limited. The present study investigated the occurrence of MPs sized 125 μm-5 mm in the gastrointestinal tract (GIT) of bottlenose dolphins (Tursiops truncatus) stranded in South Carolina, USA from 2017 to 2018. MPs, mostly fibers, were detected in all GITs (n = 7) of stranded bottlenose dolphins. Total suspected MPs ranged between 123 and 422 particles/individual, a high range among international studies. Comparison to other studies likely reflects differences in both methods and location. This is the first study from North America to quantify MPs in a small coastal cetacean outside Arctic waters and the first specifically in bottlenose dolphins (southeastern United States). Findings and methodology from this investigation can aid future studies examining MP in marine apex predators.

Per- and polyfluoroalkyl substances (PFASs) in blood of captive Siberian tigers in China: Occurrence and associations with biochemical parameters

Per- and polyfluoroalkyl substances (PFASs) have been ubiquitously detected in the environment and marine animals. However, little is known about these substances and their associations with health parameters in wild terrestrial mammals. In this study, we determined PFAS levels and distribution in the blood of captive Siberian tigers in Harbin, China, and evaluated potential exposure pathways by daily intake. In addition, for the first time, we explored the associations between serum PFAS concentrations and clinical parameters. Results showed that perfluorooctanoate (PFOA) was the dominant PFAS compound in blood (accounting for 64%), followed by perfluorooctanesulfonate (PFOS). In addition, 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) concentrations were also detected in blood and dietary food. Furthermore, significant positive age relationships were observed for levels of perfluoroheptanoate (PFHpA), PFOA, PFOS, and 6:2 Cl-PFESA in the blood of female tigers. Results showed that PFOA and PFOS in dietary food accounted for over 70% of total daily intake of PFASs, indicating that meat consumption is a predominant exposure pathway in tigers. We also found positive associations between higher exposure to PFASs (including PFOA, PFOS, and 6:2 Cl-PFESA) and elevated serum levels of alanine transaminase (ALT), a marker of liver damage. Thus, comprehensive health assessments of PFAS burdens in wildlife are needed.

Concentrations and profiles of organochlorine contaminants in North Pacific resident and transient killer whale (Orcinus orca) populations

Organochlorine (OC) profiles have been used as chemical "fingerprints" to infer an animal's foraging area. North Pacific killer whale (Orcinus orca) populations are exposed to different levels and patterns of OCs based on their prey, distribution, and amount of time spent in a particular area. To characterize concentrations and profiles of OCs found in various populations of North Pacific killer whales, polychlorinated biphenyls (PCBs), including dioxin-like congeners, DDTs, and hexachlorobenzene (HCB), were measured in biopsy blubber samples of photo-identified resident (fish-eating) and transient (mammal-eating) killer whales collected from 1994 through 2002 from Russian Far East waters to the waters of the west coast of the United States, representing 10 populations. We compared blubber OC concentrations based on ecotype (resident vs. transient), sex and reproductive maturity, and geographic area. We also examined OC mixtures to determine if we could detect segregated geographical areas (foraging areas) among the six populations with sufficient sample sizes. Transients had significantly higher OC concentrations than residents and adult male whales had consistently higher OC levels compared to adult females, regardless of ecotype. Our OC profile findings indicate segregated foraging areas for the North Pacific killer whales, consistent with observations of their geographic distributions. Several potential health risks have also been associated with exposure to high levels of contaminants in top-level predators including reproductive impairment, immune suppression, skeletal deformities, and carcinoma. The results of this baseline study provide information on the geographic distribution of OCs found in North Pacific killer whales, results which are crucial for assessing the potential health risks associated with OC exposure in this species.

Chemical tracers guide identification of the location and source of persistent organic pollutants in juvenile Chinook salmon (Oncorhynchus tshawytscha), migrating seaward through an estuary with multiple contaminant inputs

Understanding the spatial extent, magnitude, and source of contaminant exposure in biota is necessary to formulate appropriate conservation measures to reduce or remediate contaminant exposure. However, obtaining such information for migratory animals is challenging. Juvenile Chinook salmon (Oncorhynchus tshawytscha), a threatened species throughout the US Pacific Northwest, are exposed to persistent organic pollutants (POPs), including polybrominated diphenyl ether (PBDE) flame retardants and polychlorinated biphenyls (PCBs), in many developed rivers and estuaries. This study used three types of complementary chemical tracer data (contaminant concentrations, POP fingerprints, and stable isotopes), to determine the location and source of contaminant exposure for natural- and hatchery-origin Chinook salmon migrating seaward through a developed watershed with multiple contaminant sources. Concentration data revealed that salmon were exposed to and accumulated predominantly PBDEs and PCBs in the lower mainstem region of the river, with higher PBDEs in natural- than hatchery-origin fish but similar PCBs in both groups, associated with differences in contaminant inputs and/or habitat use. The POP fingerprints of the natural-origin-fish captured from this region were also distinct from other region and origin sample groups, with much higher proportions of PBDEs in the total POP concentration, indicating a different contaminant source or habitat use than the hatchery-origin fish. Stable isotopes, independent tracers of food sources and habitat use, revealed that natural-origin fish from this region also had depleted δ¹⁵N signatures compared to other sample groups, associated with exposure to nutrient-rich wastewater. The PBDE-enhanced POP fingerprints in these salmon were correlated with the degree of depletion in nitrogen stable isotopes of the fish, suggesting a common wastewater source for both the PBDEs and the nitrogen. Identification of the location and source of contaminant exposure allows environmental managers to establish conservation measures to control contaminant inputs, necessary steps to improve the health of Chinook salmon and enhance their marine survival.

First evaluation of legacy persistent organic pollutant contamination status of stranded Yangtze finless porpoises along the Yangtze River Basin, China

Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis), inhabiting the Yangtze River, are an endangered species in China. They are threatened by various kinds of pollutants, among which persistent organic pollutants (POPs) are of special concern due to their toxicities, high persistency and bioaccumulation potential. To better understand the POP contamination status of Yangtze finless porpoises, an investigation of stranded porpoises along the Yangtze River and adjacent two major lakes in the Yangtze River basin was conducted; the concentrations of four groups of legacy POPs, i.e., hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyl (PCBs), were determined in the blubber samples. The mean concentrations of ΣHCHs (the sum of all congeners/isomers), ΣDDTs, ΣPBDEs and ΣPCBs, were 1670 ± 4210, 28,800 ± 52,300, 141 ± 174, and 1020 ± 1070 ng/g lipid weight, respectively; the high DDTs/PCBs ratio reflected a strong influence of agricultural pollution in the Yangtze River basin, and the high α/γ ratio of HCH isomers indicated the usage of lindane in the corresponding areas; the predominance of low-brominated congeners of PBDEs may be related to congruent patterns in the related environmental matrices. A hazard quotient risk assessment revealed that DDTs could pose a relatively high risk to Yangtze finless porpoises compared with the risks posed by the other POPs.

Temporal Trends in Per- and Polyfluoroalkyl Substances in Bottlenose Dolphins (Tursiops truncatus) of Indian River Lagoon, Florida and Charleston, South Carolina

Temporal trends in plasma concentrations of per- and polyfluoroalkyl substances (PFAS) in free-ranging bottlenose dolphins (Tursiops truncatus) inhabiting two geographic areas: Indian River Lagoon, Florida over the years 2003-2015 and the waters surrounding Charleston, South Carolina over 2003-2013, were examined. Nine PFAS met the inclusion criteria for analysis based on percent of values below level of detection and sampling years. Proportionate percentiles parametric quantile regression assuming lognormal distributions was used to estimate the average ratio of PFAS concentrations per year for each chemical. Plasma concentrations decreased over time for perfluorodecanoate (PFDA), perfluorohexane sulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and perfluoroundecanoate (PFUnDA) in both locations. Perfluorononanoate (PFNA) decreased with time in Indian River Lagoon dolphins. Perfluorododecanoate (PFDoDA) concentrations significantly increased over time among female Indian River Lagoon dolphins. Regulation and phaseout of specific PFAS groups may have led to the decreasing levels of those PFAS and increasing levels of other replacement PFAS.

Organ-specific bioaccumulation of PCBs and PAHs in African sharptooth catfish (Clarias gariepinus) and common carp (Cyprinus carpio) from the Hartbeespoort Dam, South Africa

The distribution of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the muscle, liver, spleen and kidney tissue of two fish species was studied using an optimised diatomaceous earth assisted modified QuEChERS extraction method. Five-year-old free-ranging male African sharptooth catfish (Clarias gariepinus) and 5-year-old male common carp (Cyprinus carpio) sampled from the Hartbeespoort Dam in South Africa were used for method development. Acetonitrile extraction produced more precise recoveries than hexane extraction. Fluorene and naphthalene were the most abundant PAHs detected in the majority of fish tissues analysed. PAH bioaccumulation in 5-year-old carp and 5-year-old catfish was in the order muscle > kidney > liver > spleen and liver > muscle > kidney > spleen, respectively. PCBs were mostly detected in carp spleen and kidney. Two-year-old carp were analysed to determine PCB and PAH bioaccumulation trends. The differences in ∑16PAH concentrations between the four organs tested were all statistically insignificant for the 3 fish tested (p > 0.05). All other organs with the exception of 5-year-old carp spleen and 5-year-old carp kidney recorded total 31 PCB concentrations (∑31PCB) < 25 ng g^-1. Only 5-year-old carp spleen (∑31PCB of 592 ng g^-1) and 5-year-old carp kidney (∑31PCB of 561 ng g^-1) had significant differences (p < 0.05) from the spleen and kidney in 5-year-old catfish and 2-year-old carp. Whilst the carp and catfish sampled can be considered low PCB risk foods, 5-year-old carp muscle can be considered to be a high PAH risk food, with a benzo(a)pyrene concentration of 7 μg g^-1, based on the EU Commission Regulation 2005/208/EC pertaining to the maximum permissible benzo(a)pyrene level in fresh fish muscle.

High pollutant exposure level of the largest European community of bottlenose dolphins in the English Channel

The objective of this study was to assess the levels of persistent organic pollutants (POPs) and mercury (T-Hg) in the blubber and skin, respectively, of the free-ranging bottlenose dolphins, Tursiops truncatus, from the Normanno-Breton Gulf, one of the largest identified coastal population in Europe. Among all the POPs analysed in this study, the ∑NDL-PCBs were the most abundant compounds found in the blubber (mean: 1.33 × 10⁵-0.65 × 10⁵ ng.g^-1 lipid weight (lw) for males and females respectively), followed by ∑DDX (1.11 × 10⁴-4.67 × 10³ ng.g^-1 lw) > ∑DL-PCBs (8.06 × 10³-2.62 × 10³ng.g^-1 lw) > ∑PBDEs (1.95 × 10³-0.64 × 10³ng.g^-1 lw) > dieldrin (1.86 × 10³-0.18 × 10³ ng.g^-1 lw) > ∑endosulfan (405-62 ng.g^-1 lw) > HCB (86-52 ng.g^-1 lw) > ∑HCHs (47-60 ng.g^-1 lw) > ∑chlordane (24-0.97 ng.g^-1 lw) > ∑PCDFs (0.3-0.1 ng.g^-1 lw) > ∑PCDDs (0.06-0.05 ng.g^-1 lw). The T-Hg concentrations were highly variable between individuals (2.45 × 10³ ng.g^-1 to 21.3 × 10³ ng.g^-1 dry weight, dw). The reported concentrations are among the highest reported for cetaceans. We strongly recommend that the Normanno-Breton Gulf be a special area of conservation (cSAC) candidate because it contains the last large European population of bottlenose dolphins (rare or threatened within a European context) designated under the EC Habitats Directive.

Environment, endocrinology, and biochemistry influence expression of stress proteins in bottlenose dolphins

Natural and anthropogenic stressors have been reported to impact the health of marine mammals. Therefore, investigation of quantifiable biomarkers in response to stressors is required. We hypothesized that stress protein expression would be associated with biological and health variables in wild and managed-care bottlenose dolphins (Tursiops truncatus). To test this hypothesis, our study objectives were to (1) determine if stress proteins in skin, white blood cells (WBCs), and plasma could be measured with an antibody-based microarray, (2) measure stress-protein expression relative to biological data (location, sex, age, environment), and (3) determine if stress-protein expression was associated with endocrine, hematological, biochemical and serological variables and gene expression in bottlenose dolphins. Samples were collected from two wild groups (n = 28) and two managed-care groups (n = 17). Proteins involved in the HPA axis, apoptosis, proteotoxicity, and inflammation were identified as stress proteins. The expression of 3 out of 33 proteins was significantly (P < 0.05) greater in skin than plasma and WBCs. Male dolphins had significantly greater expression levels for 10 proteins in skin compared to females. The greatest number of stress-associated proteins varied by the dolphins' environment; nine were greater in managed-care dolphins and 15 were greater in wild dolphins, which may be related to wild dolphin disease status. Protein expression in skin and WBCs showed many positive relationships with measures of plasma endocrinology and biochemistry. This study provides further understanding of the underlying mechanisms of the stress response in bottlenose dolphins and application of a combination of novel methods to measure stress in wildlife.

Biochemical and molecular biomarkers in integument biopsies of free-ranging coastal bottlenose dolphins from southern Brazil

Adverse effects of exposure to persistent organic pollutants (POPs) threaten the maintenance of odontocete populations. In southern Brazil, coastal bottlenose dolphins from the Laguna Estuarine System (LES) and Patos Lagoon Estuary (PLE) were sampled using remote biopsies during the winter and summer months. Levels of bioaccumulated POPs were measured in the blubber. The activities of glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) were also quantified, as were the mRNA transcript levels of aryl hydrocarbon receptor (AhR), AhR nuclear translocator (ARNT), cytochrome P450 1A1-like (CYP1A1), metallothionein 2A (MT2A), GST-π, GPx-4, GR, interleukin 1 alpha (IL-1α), and major histocompatibility complex II (MHCII) in the skin. In general, levels of POPs were similar among sites, sexes, ages and seasons. For most animals, total polychlorinated biphenyl (ΣPCBs) levels were above the threshold level have physiological effects and pose risks to cetaceans. The best-fitting generalized linear models (GLMs) found significant associations between GR, IL-1α and GPx-4 transcript levels, SOD and GST activities, and total polybrominated diphenyl ether (ΣPBDEs) and pesticide levels. GLMs and Kruskal-Wallis analyses also indicated that there were higher transcript levels for most genes and lower GST activity in the winter. These results reinforce the need to consider the influence of environmental traits on biomarker values in wildlife assessments.

Comparative Innate and Adaptive Immune Responses in Atlantic Bottlenose Dolphins (Tursiops truncatus) With Viral, Bacterial, and Fungal Infections

Free-ranging Atlantic bottlenose dolphins (n = 360) from two southeastern U.S. estuarine sites were given comprehensive health examinations between 2003 and 2015 as part of a multi-disciplinary research project focused on individual and population health. The study sites (and sample sizes) included the Indian River Lagoon (IRL), Florida, USA (n = 246) and Charleston harbor and associated rivers (CHS), South Carolina, USA (n = 114). Results of a suite of clinicoimmunopathologic tests revealed that both populations have a high prevalence of infectious and neoplastic disease and a variety of abnormalities of their innate and adaptive immune systems. Subclinical infections with cetacean morbillivirus and Chlamydiaceae were detected serologically. Clinical evidence of orogenital papillomatosis was supported by the detection of a new strain of dolphin papillomavirus and herpesvirus by molecular pathology. Dolphins with cutaneous lobomycosis/lacaziasis were subsequently shown to be infected with a novel, uncultivated strain of Paracoccidioides brasiliensis, now established as the etiologic agent of this enigmatic disease in dolphins. In this review, innate and adaptive immunologic responses are compared between healthy dolphins and those with clinical and/or immunopathologic evidence of infection with these specific viral, bacterial, and fungal pathogens. A wide range of immunologic host responses was associated with each pathogen, reflecting the dynamic and complex interplay between the innate, humoral, and cell-mediated immune systems in the dolphin. Collectively, these studies document the comparative innate and adaptive immune responses to various types of infectious diseases in free-ranging Atlantic bottlenose dolphins. Evaluation of the type, pattern, and degree of immunologic response to these pathogens provides novel insight on disease immunopathogenesis in this species and as a comparative model. Importantly, the data suggest that in some cases infection may be associated with subclinical immunopathologic perturbations that could impact overall individual and population health.

Perfluoroalkyl substances (PFASs) in edible fish species from Charleston Harbor and tributaries, South Carolina, United States: Exposure and risk assessment

Concentrations of 11 PFASs were determined in muscle and whole fish for six species collected from Charleston, South Carolina (SC) for the assessment of potential health risks to humans and wildlife. Across all species and capture locations, total PFAS levels in whole fish were significantly higher than fillets by a factor of two- to three-fold. Mean ∑PFAS concentrations varied from 12.7 to 33.0 ng/g wet weight (ww) in whole fish and 6.2-12.7 ng/g ww in fillets. For individual whole fish, ∑PFASs ranged from 12.7 ng/g ww in striped mullet to 85.4 ng/g ww in spotted seatrout, and in fillets individual values ranged from 6.2 ng/g ww in striped mullet to 27.9 ng/g ww in spot. The most abundant compound in each species was perfluorooctane sulfonate (PFOS), comprising 25.5-69.6% of the ∑PFASs. Striped mullet had significantly lower relative amounts of PFOS compared to all other species and higher relative amounts of PFUnDA compared to Atlantic croaker, spotted seatrout, and spot. Unlike whole fish, PFAS levels in fillets varied significantly by location with higher ∑PFOS from the Ashley River than the Cooper River and Charleston Harbor, which reflects the levels of PFASs contamination in these systems. In whole fish, differences in relative concentrations of PFOS, PFNA, and PFDA occurred by capture location, suggestive of different sources. PFOS concentrations for southern flounder and spotted seatrout fillets were within the advisory range to limit fish consumption to 4 meals a month. PFOS levels exceeded screening values to protect mammals in 83% of whole fish examined and represent a potential risk to wildlife predators such as dolphins.

Linking organochlorine contaminants with demographic parameters in free-ranging common bottlenose dolphins from the northern Adriatic Sea

Marine top predators, including marine mammals, are known to bio-accumulate persistent pollutants such as polychlorinated biphenyls (PCBs), a serious conservation concern for these species. Although PCBs declined in European seas since the 1970s-1980s ban, considerable levels still persist in European and Mediterranean waters. In cetaceans, stranded animals are a valuable source of samples for pollutant studies, but may introduce both known and unknown biases. Biopsy samples from live, free-ranging cetaceans offer a better alternative for evaluating toxicological burdens of populations, especially when linked to known histories of identified individuals. We evaluated PCB and other organochlorine contaminants in free-ranging common bottlenose dolphins (Tursiops truncatus) from the Gulf of Trieste (northern Adriatic Sea), one of the most human-impacted areas in the Mediterranean Sea. Biopsies were collected from 32 male and female dolphins during 2011-2017. All animals were photo-identified and are part of a well-known population of about 150 individuals monitored since 2002. We tested for the effects of sex, parity and social group membership on contaminant concentrations. Males had significantly higher organochlorine concentrations than females, suggesting offloading from reproducing females to their offspring via gestation and/or lactation. Furthermore, nulliparous females had substantially higher concentrations than parous ones, providing further support for maternal offloading of contaminants. Overall, 87.5% of dolphins had PCB concentrations above the toxicity threshold for physiological effects in experimental marine mammal studies (9 mg/kg lw), while 65.6% had concentrations above the highest threshold published for marine mammals based on reproductive impairment in ringed seals (41 mg/kg lw). The potential population-level effects of such high contaminant levels are of concern particularly in combination with other known or suspected threats to this population. We demonstrate the utility of combining contaminant data with demographic parameters such as sex, reproductive output, etc., resulting from long-term studies.

Perfluorinated Alkyl Acids in Hawaiian Cetaceans and Potential Biomarkers of Effect: Peroxisome Proliferator-Activated Receptor Alpha and Cytochrome P450 4A

Perfluorinated alkyl acids (PFAAs) are persistent in marine biota and are toxic to many species, including marine mammals. We measured the concentrations of 15 PFAAs in liver and kidney samples of 16 species of stranded cetaceans from Hawai'i and other tropical North Pacific regions utilizing high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Eleven PFAAs in liver and nine PFAAs in kidney were detected, including substantial perfluorooctanesulfonate (PFOS) and perfluoroundecanoic acid (PFUnA). Regression models indicated that phylogenetic family and age class significantly influenced concentrations of certain PFAAs. PFAAs can activate transcription factor peroxisome proliferator-activated receptor alpha (PPARα), which induces transcription of cytochrome P450 4A (CYP4A). Relative expression of PPARα and CYP4A mRNA was quantified using real-time PCR (qPCR) and CYP4A protein expression, using Western blot and then compared to PFAA concentrations in liver and kidney. Concentrations of four PFAA congeners, summation of perfluoroalkyl carboxylic acids (ΣPFCAs), and ΣPFAAs correlated significantly with PPARα mRNA expression and CYP4A protein expression in kidney, suggesting either may be biomarkers of PFAA exposure in cetaceans. This is the first study to quantify PFAAs in marine mammals from this region and the first observation of a direct relationship between PFAA exposure and PPARα and CYP4A expression in cetaceans.

1H NMR metabolomic analysis of skin and blubber of bottlenose dolphins reveals a functional metabolic dichotomy

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.

Substituted diphenylamine antioxidants and benzotriazole UV stabilizers in blood plasma of fish, turtles, birds and dolphins from North America

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are additives used in industrial and commercial applications to prevent degradation by oxidation and are contaminants of emerging environmental concern. Little is known about the fate of these contaminants in wildlife, particularly in reptiles, birds and marine mammals. Nine SDPAs and six BZT-UVs were measured in blood plasma of seven fish species, snapping turtles (Chelydra serpentina), double-crested cormorants (Phalacrocorax auritus), and bottlenose dolphins (Tursiops truncatus) from various locations in North America. Plasma SDPAs were more frequently (90-100%) detected and with higher concentrations (median: 25-270 pg g^-1, wet weight (ww)) in organisms from urban areas than rural locations (median: <method limits of quantification -136 pg g^-1). The concentrations of most SDPAs generally followed the order of fish ≥ snapping turtles > double-crested cormorants > bottlenose dolphins. Of the three quantifiable BZT-UVs, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328) showed higher detection frequency in most species of fish, bird and turtle (range of 0-67%), indicating the widespread distribution of UV328 in the aquatic environment of lower Great Lakes region.

Persistent organic pollutants in fish from Charleston Harbor and tributaries, South Carolina, United States: A risk assessment

Fish consumption is an important route of exposure to persistent organic pollutants (POPs) in dolphins as well as humans. In order to assess the potential risks associated with these contaminants, 39 whole fish and 37 fillets from fish representing species consumed by dolphins and humans captured from Charleston Harbor and tributaries, South Carolina, USA, were measured for a suite of POPs. Polychlorinated biphenyls (PCBs) were the predominant contaminant with concentrations ranging from 5.02 to 232.20 ng/g in whole fish and 5.42-131.95 ng/g in fillets (weight weight ww) followed by total organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). Total POPs levels varied by location and species with general trends indicating significantly higher levels in fish from the Cooper (93.4 ng/g ww) and Ashley Rivers (56.2 ng/g ww) compared to Charleston Harbor (31.6 ng/g ww). Mullet and spot were found to have significantly higher PCBs, OCPs and total POPs, 2-3 times higher than red drum; mullet were also significantly higher in OCPs compared to seatrout. PCB concentrations in whole fish and fillets exceeded EPA human screening values for cancer risk in all fish sampled. For PCBs in fillets, all samples had values of maximum allowable meals per month that were less than the EPA, FDA guidelines for recommended fish meals per month, suggesting lower (more stringent) allowable fish meals per month. All fish exceeded PBDE wildlife values and all fish except two exceeded the level where 95% of the dolphin population would have tissue levels below the health effect threshold. Considering that POP concentrations in fish potentially consumed by humans exceed human health effect thresholds levels, consumption advisories should be considered as a prudent public health measure.

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.

River otters (Lontra canadensis) "trapped" in a coastal environment contaminated with persistent organic pollutants: Demographic and physiological consequences

Productive coastal and estuarine habitats can be degraded by contaminants including persistent organic pollutants (POPs) such as PCBs, dioxins, and organochlorine insecticides to the extent of official designation as contaminated sites. Top-predatory wildlife may continue to use such sites as the habitat often appears suitable, and thus bioaccumulate POPs and other contaminants with potential consequences on their health and fitness. Victoria and Esquimalt harbours are located on southern Vancouver Island, British Columbia (BC) and are federally designated contaminated sites due mainly to past heavy industrial activities, such as from shipyards and sawmills. We collected scat samples from river otters (Lontra canadensis) throughout an annual cycle, and combined chemical analysis with DNA genotyping to examine whether the harbour areas constituted a contaminant-induced ecological trap for otters. We confirmed spatial habitat use by radio telemetry of a subsample of otters. Fifteen percent of otter scat contained PCB concentrations exceeding levels considered to have adverse effects on the reproduction of mink (Neovison vison), and there were significant positive correlations between concentrations of PCBs and of thyroid (T3) and sex (progesterone) hormones in fecal samples. Radio telemetry data revealed that otters did not show directional movement away from the harbours, indicating their inability to recognize the contaminated site as a degraded habitat. However, analysis and modeling of the DNA genotyping data provided no evidence that the harbour otters formed a sink population and therefore were in an ecological trap. Despite the highly POP-contaminated habitat, river otters did not appear to be adversely impacted at the population level. Our study demonstrates the value of combining chemical and biological technologies with ecological theory to investigate practical conservation problems.

Preliminary Assessment of Legacy and Current-Use Pesticides in Franciscana Dolphins from Argentina

The change towards intensive agriculture has led to an increase in the use of pesticides. In addition, legacy pesticides, such as organochlorines are still present in the environment. Ten Franciscana dolphins were accidentally killed by netting in a coastal area of Argentina in Buenos Aires province. From these animals, organochlorine, organophosphate and pyrethroid pesticides were analyzed in liver, bubbler and melon tissues. The concentrations of Σendosulfan ranged from not detectable values (nd) to 3539 ng g^-1 lw, with the maximum level in melon tissue. DDE was present in 60% of all samples at concentrations from nd to 6672 ng g^-1 lw, indicating historical DDT contamination. The presence of endosulfan and heptachlor in a nursling calf indicated a transfer of these pesticides through lactational and placental transport. The concentrations of organophosphates and pyrethroids were below the limit of detection, reflecting the low persistence of these compounds.

Levels and trends of polycyclic aromatic hydrocarbons in the Indo-Pacific humpback dolphins from the Pearl River Estuary (2012-2017)

We investigated the levels and trends of the 16 USEPA priority PAHs in the blubber of 37 Indo-Pacific humpback dolphins sampled during the period 2012-2017 from the Pearl River Estuary (PRE), China. Σ₁₆PAHs concentrations (17.6-6080 ng g^-1 wet weight) were at median level compared to dolphin species worldwide. Humpback dolphins affiliated with the hotspots of PAHs, had significantly higher levels of Σ₁₆PAHs than individuals from the other areas in the PRE. Moreover, dolphins stranded on the coast of Lingdingyang are significantly more contaminated by Σ₁₆PAHs than those in the West-four region of the PRE, which appears to reflect the heterogeneous distribution of PAHs in the environment. A marked decline in blubber Σ₁₆PAHs levels is observed over the studied period, with the control of a range of confounding factors. The trend is strongly and statistically significant (p < 0.0001), indicating that the loading of PAHs are gradually being reduced.

Contamination status by persistent organic pollutants of the Atlantic spotted dolphin (Stenella frontalis) at the metapopulation level

The Atlantic spotted dolphin (Stenella frontalis) is an endemic species of the tropical-temperate Atlantic Ocean with widespread distribution. Although this species has been the subject of a large number of studies throughout its range, it remains in the "data deficient" category of the International Union for Conservation of Nature (IUCN). Chemical pollution by persistent organic pollutants (POPs) has been listed as one of the major threats to this species, however, there is no information on a wide scale. Thus, the aim of the present study was to investigate the contamination status of spotted dolphins on the metapopulation level as well as determine spatial and temporal variations in POP concentrations and bio-accumulation. A total of 115 blubber samples collected from a large part of the Atlantic basin were analysed for PCBs, DDTs, PBDEs, chlordanes, HCB and mirex. Although PCBs and DDTs were the predominant compounds in all areas, inter-location differences in POP concentrations were observed. Dolphins found at São Paulo, southeastern coast of Brazil, had the highest PCB concentrations (median: 10.5 μg/g lw) and Canary Islands dolphins had the highest DDT concentrations (median: 5.13 μg/g lw). Differences in PCB patterns among locations were also observed. Dolphins from the Azores and São Paulo demonstrated a similar pattern, with relatively highly contributions of tetra- (6.8 and 5.2%, respectively) and penta-CBs (25.6 and 23.8%, respectively) and lower contributions of hepta-CBs (20.8 and 23.5%, respectively) in comparison to other areas. Moreover, the sex of the animals and the year in which sampling or capture occurred exerted an important influence on the majority of the POPs analysed. Comparisons with toxicity thresholds available in the literature reveal that the São Paulo and Canary Island dolphins are the most vulnerable populations and should be considered in future conservation and management programs for the Atlantic spotted dolphin.

Temporal Changes and Stereoisomeric Compositions of 1,2,5,6,9,10-Hexabromocyclododecane and 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane in Marine Mammals from the South China Sea

Stereoisomeric compositions of 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) were investigated in the blubber of two species of marine mammals, finless porpoises ( Neophocaena phocaenoides) and Indo-Pacific humpback dolphins ( Sousa chinensis), from the South China Sea between 2005 and 2015. The concentrations of ΣHBCD in samples of porpoise ( n = 59) and dolphin ( n = 32) ranged from 97.2 to 6,260 ng/g lipid weight (lw) and from 447 to 45,800 ng/g lw, respectively, while those of ΣTBECH were both roughly 2 orders of magnitude lower. A significant increasing trend of ΣHBCD was found in dolphin blubber over the past decade. The diastereomeric profiles exhibited an absolute predominance of α-HBCD (mostly >90%), while the proportions of four TBECH diastereomers in the samples appeared similar. A preferential enrichment of the (-)-enantiomers of α-, β-, and γ-HBCD was found in most blubber samples. Interestingly, the body lengths of porpoises showed a significant negative correlation with the enantiomer fractions of α-HBCD. Significant racemic deviations were also observed for α-, γ-, and δ-TBECH enantiomeric pairs. This is the first report of the presence of TBECH enantiomers in the environment. The estimated hazard quotient indicates that there is a potential risk to dolphins due to HBCD exposure.