Mink as a sentinel species in environmental health

Potential exposure of native wildlife to anticoagulant rodenticides in Gran Canaria (Canary Islands, Spain): Evidence from residue analysis of the invasive California Kingsnake (Lampropeltis californiae)

Anticoagulant rodenticides (ARs), particularly second-generation compounds (SGARs), are extensively used in pest management, impacting non-target wildlife. The California kingsnake (Lampropeltis californiae), an invasive species in Gran Canaria, is under a control plan involving capture and euthanasia. This research aimed to detect 10 different ARs in these snakes, explore geographical and biometrical factors influencing AR exposure, and assess their potential as sentinel species for raptors, sharing similar foraging habits. Liver samples from 360 snakes, euthanized between 2021 and 2022, were analysed for ARs using LC-MS/MS. Results showed all detected rodenticides were SGARs, except for one instance of diphacinone. Remarkably, 90 % of the snakes tested positive for ARs, with over half exposed to multiple compounds. Brodifacoum was predominant, found in over 90 % of AR-positive snakes, while bromadiolone and difenacoum were also frequently detected but at lower levels. The study revealed that larger snakes and those in certain geographic areas had higher AR concentrations. Snakes in less central or more peripheral areas showed lower levels of these compounds. This suggests a correlation between the snakes' size and distribution with the concentration of ARs in their bodies. The findings indicate that the types and prevalence of ARs in California kingsnakes on Gran Canaria mirror those in the island's raptors. This similarity suggests that the kingsnake could serve as a potential sentinel species for monitoring ARs in the ecosystem. However, further research is necessary to confirm their effectiveness in this role.

Compound-specific stable isotopes of amino acids reveal influences of trophic level and primary production sources on mercury concentrations in fishes from the Aleutian Islands, Alaska

Total mercury concentrations ([THg]) exceed thresholds of concern in some Steller sea lion (Eumetopias jubatus) tissues from certain portions of the Aleutian Islands, Alaska. We applied compound-specific stable isotope analyses of both carbon and nitrogen in amino acids from fish muscle tissue to quantify the proportional contributions of primary production sources and trophic positions of eight prey species (n = 474 total) that are part of Steller sea lion diets. Previous THg analyses of fish muscle, coupled with monomethylmercury analyses of a subset of samples, substantiated previous findings that fishes from the west of Amchitka Pass, a discrete oceanographic boundary of the Aleutian Archipelago, have higher muscle Hg concentrations relative to fishes from the east. The δ13C values of essential amino acids (EAAs) in fish muscle demonstrated that although most fishes obtained their EAAs primarily from algae, some species varied in the extent to which they relied on this EAA source. The δ15N values of phenylalanine (0.9 to 7.8 ‰), an indicator of the isotopic baseline of a food web, varied widely within and among fish species. Trophic position estimates, accounting for this baseline variation, were higher from the west relative to the east of the pass for some fish species. Trophic magnification slopes using baseline-corrected trophic position estimates indicated similar rates of Hg biomagnification to the east and west of Amchitka Pass. Multiple linear regression models revealed that trophic position was the most important driver of fish muscle [THg] with less variation explained by other parameters. Thus, higher trophic positions but not the rate of Hg biomagnification to the west of Amchitka Pass may play a role in the regional differences in both fish and Steller sea lion [THg]. Although, differences in Hg contamination and uptake at the base of the east and west food webs could not be excluded.

Mercury and selenium concentrations in lanugo of free-ranging California sea lions in the southern Gulf of California, Mexico

Total mercury ([THg]) and selenium ([TSe]) concentrations were determined in California sea lion (Zalophus californianus) lanugo from the Gulf of California in 2021 and 2022. Relationships with sex, morphometrics, and year were evaluated. Following toxicological thresholds of concern for piscivorous mammals, most pups had a [THg] < 10 ppm, one pup (2021) had a [THg] > 20 ppm, no pups had a [THg] > 30 ppm. Females had significantly higher [TSe] than males; sex did not influence [THg]. [THg] and [TSe] in 2022 were significantly higher in the general population and male cohorts compared to 2021. Significant negative correlations were observed between [THg], [TSe], and morphometrics (2021). These results indicate that, compared to other pinniped species, regional California sea lions may have a decreased likelihood of experiencing Hg-related adverse health effects. Year-related changes in element concentrations suggest continued monitoring of this population to assess pinniped, environmental, and potentially, human health.

Human Disturbance Increases Health Risks to Golden Snub-Nosed Monkeys and the Transfer Risk of Pathogenic Antibiotic-Resistant Bacteria from Golden Snub-Nosed Monkeys to Humans

From the perspective of interactions in the human-animal-ecosystem, the study and control of pathogenic bacteria that can cause disease in animals and humans is the core content of "One Health". In order to test the effect of human disturbance (HD) on the health risk of pathogenic antibiotic-resistant bacteria (PARBs) to wild animals and transfer risk of the PARBs from wild animals to humans, golden snub-nosed monkeys (Rhinopithecus roxellana) were used as sentinel animals. Metagenomic analysis was used to analyze the characteristics of PARBs in the gut microbiota of golden snub-nosed monkeys. Then, the total contribution of antibiotic resistance genes (ARGs) and virulence factors (VFs) of the PARBs were used to assess the health risk of PARBs to golden snub-nosed monkeys, and the antimicrobial drug resistance and bacterial infectious disease of PARBs were determined to assess the transfer risk of PARBs from golden snub-nosed monkeys to humans. There were 18 and 5 kinds of PARBs in the gut microbiota of golden snub-nosed monkeys under HD (HD group) and wild habitat environments (W group), respectively. The total health risks of PARBs to the W group and the HD group were -28.5 × 10-3 and 125.8 × 10-3, respectively. There were 12 and 16 kinds of KEGG pathways of human diseases in the PARBs of the W group and the HD group, respectively, and the gene numbers of KEGG pathways in the HD group were higher than those in the W group. HD increased the pathogenicity of PARBs to golden snub-nosed monkeys, and the PARBs in golden snub-nosed monkeys exhibited resistance to lincosamide, aminoglycoside, and streptogramin antibiotics. If these PARBs transfer from golden snub-nosed monkeys to humans, then humans may acquire symptoms of pathogens including Tubercle bacillus, Staphylococcus, Streptococcus, Yersinia, Pertussis, and Vibrio cholera.

Pets, Genuine Tools of Environmental Pollutant Detection

In a shared environment, our companion animals became unintended sentinels for pollutant exposure consequences, developing even earlier similar conditions to humans. This review focused on the human-pet cohabitation in an environment we all share. Alongside other species, canine and feline companions are veritable models in human medical research. The latency period for showing chronic exposure effects to pollutants is just a few years in them, compared to considerably more, decades in humans. Comparing the serum values of people and their companion animals can, for example, indicate the degree of poisonous lead load we are exposed to and of other substances as well. We can find 2.4 times higher perfluorochemicals from stain- and grease-proof coatings in canine companions, 23 times higher values of flame retardants in cats, and 5 times more mercury compared to the average levels tested in humans. All these represent early warning signals. Taking these into account, together with the animal welfare orientation of today's society, finding non-invasive methods to detect the degree of environmental pollution in our animals becomes paramount, alongside the need to raise awareness of the risks carried by certain chemicals we knowingly use.

Associations between faecal chemical pollutants and hormones in primates inhabiting Kibale National Park, Uganda

While anthropogenic pollutants are known to be a threat to primates, our understanding of exposure to pollutants in situ and their sub-lethal effects is still limited. We used non-invasive biomonitoring to examine associations between faecal concentrations of 97 chemical pollutants and faecal hormone metabolites of cortisol and oestradiol in four primate species inhabiting Kibale National Park, Uganda (chimpanzees-Pan troglodytes, olive baboons-Papio anubis, red colobus-Piliocolobus tephrosceles and red-tailed monkeys-Cercopithecus ascanius). Across all species (n = 71 samples), results demonstrated positive associations of organochlorine pesticides (OCPs) (β = 0.143, p = 0.020) and organophosphate esters (β = 0.112, p = 0.003) with cortisol in adult females. Additionally, we observed positive associations of OCPs (β = 0.192, p = 0.013) and brominated flame retardants (β = 0.176, p = 0.004) with cortisol in juveniles. Results suggest that cumulative pesticides and flame retardants are disruptive to endocrine function in these populations, which could have implications for development, metabolism and reproduction. Our study further demonstrates that faeces can be an important, non-invasive matrix for examining pollutant-hormone associations in wild primates and other critical wildlife populations.

Red fox as a potential bioindicator of metal contamination in a European environment

In times of widespread environmental pollution with heavy metals of anthropogenic origin and the increasing dynamics of this process, it is justified to collect as much data as possible on the concentration of metals in terrestial mammals from unpolluted areas. The purpose of this research was to present the concentration of essential (chromium, copper, iron, manganese, molybdenum, and zinc), probably essential (nickel, vanadium) and non-esential element (cadmium, lead, silver, strontium, and tin) in the liver, kidneys, muscles and brain of red fox (Vulpes vulpes) inhabiting north-western Poland. We revealed that the concentration of all metals, apart from Ni, was different between studied tissues. Sn and Mo have the highest affinity to the liver, whereas Ag, Sr, Cr had higher concentrations in the brain than in other organs. Various positive relationship between the concentrations of metals were observed in the tissues. Moreover, we noted negative correlations between Ag and Sn in the kidneys and brain, and between Cu and Ag in the liver. In our study the red fox was used as biomonitor for the assessment of exposure of carnivores to metals, in the generally unpolluted areas of Central Europe. Data presented in the report may be used as comparative values in similar ecotoxicological studies.

Gulls as potential sentinels for urban litter: combining nest and GPS-tracking information

The production of urban waste has increased in the past decades leading to its mishandling. The effects on public health, economy, and wildlife that waste mismanagement can have are forcing governments to increase their efforts in detecting and mitigating the presence of waste. Identifying and monitoring sentinel species to assess the presence of urban litter could be a cost-effective option. Thus, analyzing the nest composition of yellow-legged gulls from an urban population inhabiting a very high populated city (Barcelona, Spain), and combining this information with accurate GPS tracking data, provides a potential tool to monitor the presence of marine and terrestrial litter over time. The results revealed the highest presence of debris in the nests of a seabird ever recorded. All the nests examined contained anthropogenic waste, with plastic items present in all of them. Crossing the nest composition with GPS tracking movements confirmed that the waste to build the nests was collected in the urban area and not in other environments surrounding the city. Then, the nest waste composition may be a good indicator of waste mismanagement and advise the municipalities to improve waste management and recycling strategies for the different types of litter. Using gulls breeding in cities as sentinel species and, in particular, the study of their nest composition, may provide essential data to decision-making stakeholders to adopt a One Health approach and help improve not only the environment's health but also the health of those who live in it.

Mercury content in the fur of sea otters (Enhydra lutris) from the Commander Islands

The sea otter (Enhydra lutris) is a keystone species in the ecosystem which is currently in depression in Russia. The objectives of this study were to: (1) establish if the sea otters from the Commander Islands have hazardous levels of mercury (Hg) in their fur; (2) assess Hg pollution in sea otters during a period of high abundance and population depression; (3) identify the age and sex differences in sea otters by Hg content. The sea otters were classified from no to low risk for Hg health effects. Differences in Hg content during periods of low and high population size were not statistically significant. Hg concentrations in adult sea otters were significantly higher than in the young, and higher in males than in females. This study presents the first data on Hg content in sea otters' fur and the first estimate of Hg contamination for the Commander Islands population.

Total Mercury, Total Selenium, and Monomethylmercury Relationships in Multiple Age Cohorts and Tissues of Steller Sea Lions (Eumetopias jubatus)

Steller sea lion (Eumetopias jubatus) tissue mercury concentrations increasingly above thresholds of concern occur in regions of Alaska where lack of population recovery is noted. Selenium-monomethylmercury interactions may mitigate toxicosis but may also result in functional selenium deficiency, impacting essential selenium-dependent processes. Physiologically driven differences in tissue concentrations (organotropism) of total mercury ([THg]), total selenium ([TSe]), and monomethylmercury ([MeHg⁺ ]) confound interpretation for various age cohorts. Archived tissues from Alaska Steller sea lions (2002-2016) were used to compare [THg], [MeHg⁺ ], and [TSe] across age cohorts and tissue types. Liver [THg] ranged from 0.05 to 63.7 µg/g. Fetal and pup livers had significantly lower [THg] and [TSe], higher percentage MeHg⁺ , and greater range of molar TSe:THg than subadult and adult livers. Molar Se:MeHg⁺ ratios, including Se in excess of nonmethylmercury, were dependent on [MeHg⁺ ] in fetuses and pups. While [THg] varied significantly by muscle type (heart vs. skeletal) and anatomical location, concentrations were strongly correlated. Biomagnification and/or bioaccumulation of THg in liver of older animals confounded comparison with other tissues; however, in fetal and pup liver [THg] correlated with other tissues. In contrast, liver [MeHg⁺ ] correlated with other tissues across all age classes. Fetal and pup tissues, which reflect in utero exposure and are subject to limited bioaccumulation, are ideal for assessing mercury exposure related to dam diet, including intertissue comparison, and represent key cohorts of concern. Evaluating [MeHg⁺ ] and [TSe] in tissues from multiple age cohorts allows better intertissue comparison, providing insight into time courses, routes of exposure, and potential for adverse effects. Environ Toxicol Chem 2022;41:1477-1489. © 2022 SETAC.

Impacts of endocrine disrupting chemicals on reproduction in wildlife and humans

Endocrine disrupting chemicals (EDCs) are ubiquitous in aquatic and terrestrial environments. The main objective of this review was to summarize the current knowledge of the impacts of EDCs on reproductive success in wildlife and humans. The examples selected often include a retrospective assessment of the knowledge of reproductive impacts over time to discern how the effects of EDCs have changed over the last several decades. Collectively, the evidence summarized here within reinforce the concept that reproduction in wildlife and humans is negatively impacted by anthropogenic chemicals, with several altering endocrine system function. These observations of chemicals interfering with different aspects of the reproductive endocrine axis are particularly pronounced for aquatic species and are often corroborated by laboratory-based experiments (i.e. fish, amphibians, birds). Noteworthy, many of these same indicators are also observed in epidemiological studies in mammalian wildlife and humans. Given the vast array of reproductive strategies used by animals, it is perhaps not surprising that no single disrupted target is predictive of reproductive effects. Nevertheless, there are some general features of the endocrine control of reproduction, and in particular, the critical role that steroid hormones play in these processes that confer a high degree of susceptibility to environmental chemicals. New research is needed on the implications of chemical exposures during development and the potential for long-term reproductive effects. Future emphasis on field-based observations that can form the basis of more deliberate, extensive, and long-term population level studies to monitor contaminant effects, including adverse effects on the endocrine system, are key to addressing these knowledge gaps.

Fetal mercury concentrations in central California Pacific harbor seals: Associated drivers and outcomes

Mercury (Hg) is a well-known toxicant in wildlife and humans. High total Hg concentrations ([THg]) have been reported in central California harbor seals Phoca vitulina richardii. We evaluated the effects of presence/absence of early natal coat (lanugo), year (2012 to 2017), sex, stranding location, and trophic ecology (ẟ¹³C and ẟ¹⁵N values) on hair [THg] along coastal central California. Also examined were [THg] effects on growth rates of pups in rehabilitation and probability of release (e.g., successful rehabilitation). The [THg] ranged from 0.46-81.98 mg kg^-1 dw, and ẟ¹⁵N and ẟ¹³C ranged from 13.6-21.5‰, and -17.2 to -13.0‰, respectively. Stranding location, year, and presence of lanugo coat were important factors explaining variation in [THg]. Seals from Sonoma and San Mateo County had higher [THg] than other locations. Seals with full or partial lanugo coat had lower [THg]. Seals from 2016 and 2017 had higher [THg] than those from 2015. Hair [THg] exceeded lower and upper toxicological thresholds (>20 mg kg^-1 by year (5.88% to 23.53%); >30 mg kg^-1 (0% to 12.31%)) with a pronounced increase from 2015 to 2016. Pups in 2017 had significantly higher odds ratio of [THg] above 20 mg kg^-1 than pups of 2015, and pups in 2016 had significantly higher odds ratio than those from 2013 and 2015 (similar when using 30 mg kg^-1). Pups in Sonoma County had the highest odds ratio for [THg] in lanugo above 20 mg kg^-1. ẟ¹⁵N values were higher in 2015-2017, particularly relative to 2014, probably associated with the El Niño event. The [THg] was not a good predictor for probability of release and mass-specific growth rates in captivity. Further investigation of temporal trends of [THg] in harbor seals is warranted given the relatively high percentage of samples exceeding threshold values, particularly in the most recent sampling years.

Assessment of clinical outcomes associated with mercury concentrations in harbor seal pups (Phoca vitulina richardii) in central California

Monomethyl mercury (MeHg⁺) from the diet can cause mild to severe neurotoxicosis in fish-eating mammals. Chronic and low-level in utero exposure also can be neurotoxic, as documented in laboratory animal studies and epidemiologic investigations. In free-ranging animals, it is challenging to study low-level exposure related neurotoxicosis, and few studies have investigated the relationship between mercury (Hg) and adverse outcomes in wild populations. Relative to Hg concentrations on admission we evaluated different types of behaviors for 267 Pacific harbor seal (HS; Phoca vitulina richardii) pups at The Marine Mammal Center from 2015 to 2019 during rehabilitation after stranding and maternal separation. Admitted HS pups underwent a clinical exam; including sex and weight determination, and hair (partly lanugo grown in utero) and blood samples were collected for total Hg concentration ([THg]) determination. All pups were monitored weekly (behavior assessments included response to tactile stimulation, movement, swimming, interactions with other seals, hand feeding, and feeding independently), and days in rehabilitation and survival were recorded. There was a significant negative correlation between [THg] and responses to tactile stimulation and movements, measured in both hair and whole blood (p < 0.05). This relationship was found both during the intensive care unit (ICU) stage, and during the pool stage of rehabilitation. Additionally, there was a significant association between greater [THg] and number of days spent in rehabilitation, although there was no relationship between [THg] and survival. There was a significant sex difference, with greater [THg] in female pups, which contrasts with previously published findings in juvenile and adult harbor seals. Our findings support small, but significant associations between gestational THg exposure and clinical effects for tactile sensory response and movement, and longer rehabilitation durations for HS pups, although there was considerable variability among animals.

Accumulation of metals in Lasius niger: Implications for using ants as bioindicators

The high capacity of many ant species to accumulate trace metals raises the question of whether the metal concentration in ants' bodies could reliably reflect the contamination of ecosystems. The idea of applying the metal accumulation in ants for bioindication purposes is tempting; however, the methods should consider that ants are unique organisms due to their social way of life. In this study, we describe the between-colony variation in the accumulation of Zn and Cd in workers of the common garden ant Lasius niger originated from the post-mining area of a zinc-and-lead smelter in southern Poland. We show that the accumulation of both metals differs significantly between colonies even within the same study site; at the maximum, we detected a three-fold difference in Zn accumulation and a six-fold difference in Cd. The results showed that in the study area, the capacity of L. niger to accumulate metals is highly colony-specific. If future studies on other ant species concur with our findings, this may suggest that incorporating the between-colony variation of metal accumulation in prospective bioindication protocols would provide a higher accuracy of the assessments on the contamination of impacted environments. We suggest that using ants for bioindication should be preceded by preliminary studies to assess representative samples of colonies that could reliably indicate the contamination of the investigated area.

Evaluation of Mercury Contamination in Iranian Wild Cats Through Hair Analysis

Due to its environmental persistence and bioaccumulative properties, mercury is considered highly toxic to humans, ecosystems, and wildlife. The present study aimed to investigate the total mercury (Hg) concentrations in hair samples of 40 wild cats belonging to eight different species collected from various provinces of Iran and to characterize their risk of Hg exposure. Total Hg levels in Iranian wild cats ranged from 62 to 3670 ng/g dw hair, with a median value of 488 ng/g dw hair. The lowest median Hg concentration was found in west Iran (251 ng/g dw hair), while the highest median level was measured in the north-east of the country (736 ng/g dw hair), likely related to its past use in agriculture and potential contamination of industrial effluents. The overall contamination of Iranian wild cats with mercury can be considered generally low, but 20% of the samples reached levels above 1100 ng/g dw hair, set as indicative of an environmental Hg concern according to the U.S. Fish and Wildlife Service. Our data are comparable with other investigations on wildlife worldwide, confirming the suitability of museum collection specimens to assess the environmental levels of Hg. We showed that, while diet and habitat can influence the mercury accumulation in wild cats, complementary factors, such as age, size, and interspecific metabolic differences, should be considered as well in future investigations.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

A noninvasive environmental monitoring tool for brominated flame-retardants (BFRs) assisted by conservation detection dogs

Fecal matter is a useful noninvasive/nondestructive media for evaluating contaminants in wildlife, as residues therein have been observed to correlate with body burdens. Conservation detection dog-handler teams can be used to optimize the acquisition of fecal samples. To build on previous work, sentinel-species' (i.e. mink (Mustela vison) and otter (Lontra canadensis)) fecal matter was opportunistically located by a detection dog team along the tri-river system of Missoula, Montana, USA. Sediments were also collected. Samples were used to develop an analytical method from fecal matter to determine habitat exposure to the brominated flame-retardants (BFRs): polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), 2-ethylhexyl 2, 3, 4, 5-tetrabromobenzoate (EH-TBB), di (2-ethylhexyl)-2, 3, 4, 5-tetrabromophthalate (BEH-TEBP) and decabromodiphenyl ethane (DBDPE). Sediments contained PBDEs (BDE-99 and BDE-209) and EH-TBB at detection rates of 67%, 33% and 67%, respectively. BDE-99, -209 and EH-TBB were also detected in mink and otter feces, at rates of 81%, 25% and 81%, respectively; plus BEH-TEBP at 13%. BFR levels correlated positively with human population density except along the lower Bitterroot River, where BDE-209 sediment and feces levels exceeded other sites by several orders of magnitude. Fecal matter body burden estimates indicated marginal PBDE exposure. However, exposure to their replacements, EH-TBB and BEH-TEBP, were at levels that may adversely affect healthy Mustelidae populations. Proof-of-concept was achieved; validation results were within established standards for the development of analytical methods. The established application of conservation dog-handler teams to facilitate the collection of fecal matter for BFR analysis represents a valuable, but currently underutilized environmental monitoring tool.

Metal brain bioaccumulation and neurobehavioral effects on the wild rodent Liomys irroratus inhabiting mine tailing areas

Ecotoxicological studies are necessary in order to evaluate the effects of environmental exposure of chemicals on wild animals and their ecological consequences. Particularly, neurobehavioral effects of heavy metal elements on wild rodents have been scarcely investigated. In the present study, we analyzed the effect of metal bioaccumulation (Pb, As, Mg, Ni, and Zn) in the brain and in the liver on exploratory activity, learning, memory, and on some dopaminergic markers in the wild rodent Liomys irroratus living inside mine tailings, at Huautla, Morelos, Mexico. We found higher Pb concentration but lower Zn in striatum, nucleus accumbens, midbrain, and hippocampus in exposed animals in comparison to rodents from the reference site. Exposed rodents exhibited anxious behavior evaluated in the open field, while no alterations in learning were found. However, they displayed slight changes in the memory test in comparison to reference group. The neurochemical evaluation showed higher levels of dopamine and 5-hydroxyindolacetic acid in midbrain, while lower levels of metabolites dihydroxyphenyl acetic acid and homovanillic acid in striatum of exposed rodents. In addition, mRNA expression levels of dopaminergic D2 receptors in nucleus accumbens were lower in animals from the mining zone than in animals from the reference zone. This is the first study that shows that chronic environmental exposure to metals results in behavioral and neurochemical alterations in the wild rodent L. irroratus, a fact that may comprise the survival of the individuals resulting in long-term effects at the population level. Finally, we suggest the use of L. irroratus as a sentinel species for environmental biomonitoring of mining sites.

Methyl mercury (MeHg) in vitro exposure alters mitogen-induced lymphocyte proliferation and cytokine expression in Steller sea lion (Eumetopias jubatus) pups

Steller sea lions (Eumetopias jubatus, SSLs) are managed as two distinct population segments within U.S. waters: the endangered western distinct population segment and the recently delisted eastern distinct population segment. Recent studies reported concentrations of mercury in several tissues collected from young SSLs in the Aleutian Islands that were at or above concentrations found to negatively impact health in other fish-eating mammals. However, there are limited studies which have investigated the range of mercury concentrations that may negatively influence the SSL immune system. This study assessed relationships between methyl mercury (MeHg⁺) concentrations and two immune functions, lymphocyte proliferation and cytokine expression. Peripheral blood mononuclear cells (PBMCs) were isolated and cryopreserved from pups on three rookeries within the western distinct population segment: Chiswell Island, Ulak, and Agattu Islands. Lymphocyte proliferation and cytokine expression were assessed in vitro using thawed PBMCs with exposure to MeHg⁺ (unexposed control, 0.001, 0.01, and 0.1 μg/ml). Lymphocyte proliferation was measured without and with stimulation with a T cell mitogen (ConA) and B cell mitogen (LPS) and the concentration of cytokines was measured in the cell culture supernatant (with and without ConA or LPS). Spontaneous lymphocyte proliferation was significantly increased at 0.01 and 0.1 μg/ml. T lymphocyte proliferation was significantly increased at 0.001 μg/ml and 0.1 μg/ml, while B lymphocyte proliferation was decreased at 0.1 μg/ml. Cytokine concentrations for INFγ, IL-10, IL-6, and TNFα were reduced at 0.1 μg/ml upon either T or B cell mitogen stimulation, with the exception for IL-10, where 0.1 μg/ml reduced IL-10 concentration compared to unstimulated cells. These data suggest immune functions were affected by MeHg⁺ exposure requiring in vivo follow up investigations. The observed modulation of immune functions is of concern as any toxicant-induced modulation may adversely affect the health of individuals, particularly younger animals undergoing periods of critical development.

Sentinel species for biomonitoring and biosurveillance of environmental heavy metals in Nigeria

Nigeria receives copious annual precipitation to nourish its forests and agriculture, it has an extensive river drainage system, and it possesses valuable mineral deposits that stimulate both commercial and artisan mining activities. The combination of these features complicates Nigeria's efforts to produce adequate amounts of healthy foods to support its population. Toxic heavy metals like lead, cadmium, and mercury, and toxic metalloids such as arsenic, are also present in its mineral deposits and they migrate gradually into the soil and water of Nigeria by natural means. However, mining activities can liberate higher levels of toxic metals, which adversely affect Nigerian ecosystems and its food chains. Thus, environmental pollution due to anthropogenic activities is a major public health concern in Nigeria. This review covers the importance of native Nigerian and African wild and cultivated plants along with livestock and wild animals as sentinel species to evaluate heavy metals as environmental stressors and the use of sentinel species for food safety monitoring and for predicting potential risks to human health.

Long-range transport of legacy organic pollutants affects alpine fish eaten by ospreys in western Canada

Persistent organic pollutants (POPs) contaminate pristine, alpine environments through long-range transport in the atmosphere and glacier trapping. To study variation in POPs levels in western Canada, we measured levels in the prey (fish) of osprey (Pandion haliaetus) during 1999-2004, and compared those to levels in eggs and chicks. Values in fish muscle (representing human consumption) correlated with whole carcasses (wildlife consumption) for all POPs, except toxaphene, allowing us to pool data. Biomagnification factors for osprey eggs were much higher than published values from Oregon, reflecting differences in local diet. We factored baseline-corrected food chain variation by using amino acid-specific analysis of osprey eggs, illustrating how top predators (ospreys) can indicate both ecosystem-wide baselines and contamination. Given that our biomagnification factors were so different from those for the same species from a nearby site, we argue that trophic magnification factors derived from baseline-corrected δ¹⁵N are likely a more accurate method for estimating contamination. Dichlorodiphenyltrichloroethane (ΣDDT) concentrations were greatest in rainbow trout from a small lake at 1800 m, and those levels exceeded wildlife and human health guidelines. Indeed, once sites with known agricultural inputs were eliminated, elevation, percent lipids and baseline-corrected δ¹⁵N (from amino acid specific isotope values) best predicted ΣDDT. Baseline-corrected, but not bulk, δ¹⁵N was the main predictor of polychlorinated biphenyls (ΣPCB). Total toxaphene was consistently the major contaminant after ΣPCB and ΣDDT in osprey eggs, and was present in many fish samples. We concluded that toxaphene arrived from long range deposition due to high proportions of Parlar 40-50 congeners. The only exception was Paul Lake, where toxaphene was used as a piscicide, with a high concentrations of the Hex-Sed and Hep-Sed congeners at that site. We conclude that long-range transport and trophic position, not melting glaciers, were important determinants of some legacy POPs in fish and wildlife in alpine Canada.

Relationships between mercury concentrations in fur and stomach contents of river otter (Lontra canadensis) and mink (Neovison vison) in Northern Alberta Canada and their applications as proxies for environmental factors determining mercury bioavailability

The fur of piscivorous animals such as river otter (Lontra canadensis) and mink (Neovison vison) has been proposed to be used as a biomarker medium to assess mercury (Hg) exposure, but the relationship with dietary and environmental Hg exposure has not been fully characterized. The objective of this study was to investigate the relationship between fur total mercury (THg) and stomach content THg in river otter and mink, and their relationships with environmental factors. THg concentrations were measured in fur and stomach contents of river otter (n = 35) and mink (n = 30) collected from northern Alberta, Canada between 2014 and 2017. The fur THg concentration (mean ± standard deviation) was 6.36 ± 4.12 μg/g fur weight and 5.25 ± 3.50 μg/g fur weight and the average stomach content THg was 0.95 ± 0.56 μg/g dry weight and 0.71 ± 0.54 μg/g dry weight in river otter and mink respectively. There was a positive relationship between the log fur THg and log stomach contents THg for both species (p < 0.05). There was a positive relationship between the log THg of stomach contents and the percent of deciduous forest and a negative relationship with soil pH. There was a positive relationship between the log THg of fur and the total area burned by forest fire and a negative relationship with the percentage of wetlands. These results provide field evidence that fur can be used to reflect dietary Hg exposure and to identify sources and environmental factors that affect the bioavailable Hg in the habitats of these wildlife species.

Selenium and mercury in the hair of raccoons (Procyon lotor) and European wildcats (Felis s. silvestris) from Germany and Luxembourg

This study examined the concentration of total mercury (THg) and selenium (Se), as well as the molar ratio of Se:THg in hair samples of terrestrial animals. THg and Se concentrations were measured from the hair of raccoons (Procyon lotor) and European wildcats (Felis s. silvestris) from Germany and Luxembourg. Median THg concentrations in hair from raccoons and wildcats were 0.369 and 0.273 mg kg-1 dry weight (dw), respectively. Se concentrations were higher in the hair of raccoons than of wildcats (0.851 and 0.641 mg kg-1 dw, respectively). Total mercury concentration in hair of raccoons from Luxembourg was almost 5× higher that found in hair of raccoons from Germany; however, Se concentration was similar. Thus, molar ratio of Se:THg was ~4× higher in the hair of raccoons from Germany than those from Luxembourg. Significant negative correlation was found between THg concentration and Se:THg molar ratio in both wildcats and raccoons.

Effects of dietary vitamin E supplementation on the reproductive performance of yearling female mink (Neovison vison) fed wet fish-based feed

This study was conducted to investigate the effects of dietary vitamin E (VE) supplementation on the reproductive performance of female mink, preweaning growth performance of their kits, and antioxidative status and immune functions of dams and kits. Yearling mink dams (n = 180) were randomly assigned to five treatment groups (n = 36). The dietary treatments included a basal diet supplemented with VE at 0 (control), 80, 160, 320, or 640 mg/kg DM. Compared with the control, the addition of 160-320 mg/kg VE decreased (P = 0.0362) the percentage of pre-weaning mortality of mink kits. At weaning, the average body weight was greater (P = 0.0408) in kits fed 320 mg/kg supplemental VE. In mink dams, the addition of 80-320 mg/kg VE increased (P = 0.0125) serum SOD. Supplementation of 320 or 640 mg/kg VE decreased (P = 0.0260) serum reactive oxygen species (ROS). Furthermore, feeding a large dose of VE (640 mg/kg diet) resulted in increased (P = 0.0245) serum α-tocopherol. In mink kits, the addition of 320 or 640 mg/kg VE increased serum α-tocopherol (P = 0.0207) and IgG (P = 0.0464). Supplementation of 640 mg/kg VE decreased (P = 0.0471) serum ROS. The present results indicate that VE supplementation improved the antioxidative status of mink dams and enhanced the immune functions, decreased pre-weaning mortality and enhanced weaning weight of their kits. Taken together, the effective VE supplementation was 320 mg/kg of diet for yearling female mink.

Concentrations of organohalogens (PCBs, DDTs, PBDEs) in hunted and stranded Northern sea otters (Enhydra lutris kenyoni) in Alaska from 1992 to 2010: Links to pathology and feeding ecology

Many organohalogen compounds (OHCs) are persistent organic pollutants (POPs) found in appreciable concentrations in marine predators. While production of some POPs has declined or ceased in recent decades, their capacity for global transport and bioaccumulation results in observations of unchanging or increasing concentrations in marine systems. Sea otters (Enhydra lutris) have been advocated as an environmental sentinel for contaminants due to their longevity, site fidelity and prey species that often overlap with human consumption. Using archived (1992-2010) samples of livers from Northern sea otters (n = 50) from Alaska we examine concentrations of chlordanes (CHLs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), and polybrominated diphenyl ethers (PBDEs) and associated metabolites. We found some evidence for declining ΣPCBs over the two decades, however for most animals concentrations were low compared to toxicological thresholds. Six animals had relatively high concentrations of ΣPCBs (mean = 262,000 ng/g lipid weight), ΣDDTs (mean = 8,800 ng/g lw), and ΣPBDEs (mean = 4,600 ng/g lw), with four of these six animals experiencing hepatic parasitism or hepatitis. In order to assess whether differences in POP concentrations are associated with feeding ecology, we examined stable isotopes of C and N in archived muscle and whisker samples. In general, there were no significant relationships between ΣPOP concentrations and stable isotope ratios. There were small differences in stable isotope profiles in animals with high POP concentrations, although it was unclear if these differences were due to feeding ecology or disease processes. This study highlights the importance of considering feeding ecology and necropsy (health and disease status) data while conducting contaminant surveys, and confirms some previous reports of trends in OHCs in Alaska marine mammals.

Factors influencing exposure of North American river otter (Lontra canadensis) and American mink (Neovison vison) to mercury relative to a large-scale reservoir in northern British Columbia, Canada

Although reservoir creation increases fish mercury (Hg) concentrations, little information exists on its effects on Hg concentrations in aquatic mammals. River otters (Lontra canadensis) and American mink (Neovison vison) are two aquatic mammals that have been used as model species for assessing Hg bioaccumulation in aquatic systems. We assessed Hg and selenium (Se) concentrations in these two species within and outside of the Williston Reservoir (Peace-Williston (PW) watershed) in northern British Columbia (BC) and used these data to investigate potential explanatory factors (i.e., watershed, gender, trophic level (δ15N), and regional geology) influencing Hg concentrations. Hg concentrations in otter and mink inhabiting the Mackenzie watershed (outside the PW) were significantly lower than other watersheds in Northern BC. The general trend was the same for both species; the Peace-Williston having the highest and Mackenzie having the lowest Hg concentrations. For mink, the Peace-Williston watershed, higher trophic levels, and higher proportions of igneous/metamorphic bedrock were all significant influences on higher Hg concentrations (logistic regression). Higher trophic levels or proportions of of igneous/metamorphic bedrock, however, were not directly associated with the PW watershed suggesting there may be an impoundment effect. Baseline data on natural Hg inputs before planned anthropogenic changes occur is a critical first step to aiding interpretations of Hg-related effects on wildlife populations and their related ecosystems.

Perfluoroalkyl substances in diamondback terrapins (Malaclemys terrapin) in coastal South Carolina

This study focused on an estuarine wildlife species exhibiting high site fidelity and ubiquitous distribution in coastal environments along the Atlantic and Gulf coasts of the United States to monitor per- and polyfluoroalkyl substances (PFAS). A total of 75 diamondback terrapin (Malaclemys terrapin) plasma samples were collected from five creeks associated with Kiawah (Oyster Creek, Fiddler Creek, Sandy Creek, Gnat Creek) and Edisto (Townsend Creek) islands in Charleston County, South Carolina and investigated for 15 legacy PFAS. Of those, PFHxS was the only PFAS found in all terrapin plasma samples. Four additional PFAS were routinely detected (greater than 90% of the samples) and were included in statistical analyses: PFOS, PFNA, PFDA, and PFUnA. Sex-differences were observed for two creeks with male plasma containing higher PFAS than female plasma (PFHxS at Townsend Creek, PFOS at Oyster Creek). Sex-specific site differences in PFAS concentrations were observed primarily for males, suggesting male terrapins may be more sensitive indicators of localized contaminant profiles than females. Three PFAS were observed to have negative correlations with body mass: PFOS in males (p = 0.045, tau = -0.220), PFNA in males (p = 0.016, tau = -0.269), and PFHxS in both males (p = 0.007, tau = -0.302) and females (p = 0.001, tau = -0.379). No relationships for body mass and PFDA and PFUnA were observed.

Foxes (Vulpes vulpes) as sentinels for parasitic zoonoses, Toxoplasma gondii and Trichinella nativa, in the northeastern Canadian Arctic

Outbreaks of Toxoplasma gondii and Trichinella spp. have been recurring for decades among Inuit of Nunavik, northeastern Canada. Contact with wildlife has been identified as a risk factor for Inuit exposure to T. gondii, but reservoirs have yet to be confirmed based on direct detection of DNA or organism. Similarly, little is known about the occurrence of Trichinella spp. in wildlife species of Nunavik other than walrus (Odobenus rosmarus) and bears (Ursus americanus, Ursus maritimus). Foxes (Vulpes vulpes) were targeted as possible sentinels for T. gondii and Trichinella spp. because of their high trophic position within the Arctic food chain as carnivorous scavengers. A total of 39 red foxes were sampled from four communities in southern and western Nunavik between November 2015 and September 2016. For the first time in wildlife, a novel magnetic capture DNA extraction and real-time PCR technique was used to isolate and detect T. gondii DNA from the heart and brain of foxes. A double separatory funnel digestion method followed by multiplex PCR was used to recover and genotype larvae of Trichinella spp. from tongues of foxes. Seroprevalence based on detection of antibodies to T. gondii was 41% (95% CI: 27-57%) using a commercially available modified agglutination test (MAT). Detection of DNA of T. gondii and larvae of Trichinella nativa (T2) occurred in 44% (95% CI: 28-60%) and 36% (95% CI: 21-51%) of foxes, respectively. Coinfection with both T. nativa and T. gondii occurred among 23% (95%CI: 13-38%) of foxes which can be attributed to co-transmission from prey and scavenged species in their diet. There was only moderate agreement between T. gondii serology and direct detection of T. gondii DNA using the MC-PCR technique (Kappa test statistic: 0.321), suggesting that using both methods in tandem can increase the sensitivity of detection for this parasite. These findings show that foxes are good sentinels for circulation of parasitic zoonoses in terrestrial northern ecosystems since they are highly exposed, show measurable indicators of infection and do not serve as exposure sources for humans.

Determination of 16 PAHs and 22 PCBs in honey samples originated from different region of Lebanon and used as environmental biomonitors sentinel

In order to assess the air quality in some Lebanese regions, a biomonitoring study based on honey as biomonitor candidate was conducted. For this, 18 samples of honey collected from four regions in Lebanon, were analyzed for their contamination by 16 polycyclic aromatic hydrocarbons (PAHs) and 22 polychlorinated biphenyls (PCBs). Samples were first extracted using a multi-residue extraction method based on the quick, easy, cheap, effective, rugged, and safe extraction method (QuEChERS) followed by a concentration step using Solid-phase microextraction (SPME) procedures. The extraction was then followed by chromatographic analysis by gas chromatography-ion-trap tandem mass spectrometry (GC-MS/MS). After PAHs samples assessment, different ratios of founded PAHs were calculated in order to estimate the sources of the pollution by these compounds. The obtained results showed that the four analyzed regions were contaminated with PAHs originated from both pyro and petro genic sources while none of them was found to be contaminated by any of the 22 assessed PCBs. The results of this study show that honey can be used as potential biomonitor candidate allowing the assessment of the pollution statement of a given environment.

Mercury concentrations in blood, brain and muscle tissues of coastal and pelagic birds from northeastern Canada

Mercury (Hg) is a toxic element which has increased in marine environments for more than a century, due largely to anthropogenic activities, and biomagnifies in food chains to harmful levels in some top predators like waterfowl and seabirds. We analysed total mercury (THg) concentrations in blood, brain and muscle tissue from healthy specimens of 13 coastal and pelagic bird species from eastern and northern Canada to provide a baseline on current concentrations, especially for brain concentrations which are highly underrepresented in the literature. We also examined within and among tissues relationships of THg concentrations within individuals. THg concentrations were generally higher in pelagic species and scavenging gulls, when compared to coastal waterfowl. Brain and muscle tissue had similar concentrations of THg in the birds examined, but both of these tissues had lower concentrations that those found in blood. Our results, and that of a previous study, suggest that body condition has a large influence on blood THg concentrations and should be considered when using blood as a sampling medium. Many of the species we examined had tissue THg above levels known to cause deleterious, sublethal effects in some species.

Effects of halogenated contaminants on reproductive development in wild mink (Neovison vison) from locations in Canada

The concept of the Anthropocene, that humans are now re-engineering global ecosystems, is in part evidenced by the pervasive pollution by persistent organic pollutants (POPs). Certain POPs are hormone mimics and can disrupt endocrine and hence reproductive processes, shown mainly by laboratory studies with model species. There are, in contrast, fewer confirmations of such disruption from eco-epidemiological studies of wild mammals. Here we used the American mink (Neovison vison) as a sentinel species for such a study. Over the period 1998-2006, 161 mink carcasses were obtained from commercial trappers in the Canadian provinces of British Columbia and Ontario. Mink were aged, sexed, measured, and body condition assessed. Livers were analyzed either individually or pooled for organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and subsets for polybrominated diphenyl ethers (PBDEs). We primarily addressed whether contaminants affected male reproductive development by measuring baculum size and assessing the influences of age and body condition. We also considered the influence of spatial variation on relative exposure and size of baculum. Statistical models separated by age class revealed that significant relationships between baculum length or mass and juvenile mink were mostly positive, whereas for adults and first year mink they were mostly negative. A significant negative relationship for adult mink was determined between DDE and both baculum length and mass. For juvenile mink we found significant positive relationships between ∑PCBs, DDE and ∑PBDEs with baculum length. Our results provide some indication of negative effects of halogenated contaminants on male reproductive development in wild mink, and the most likely candidate chemical is the confirmed anti-androgenic compound, DDE, rather than PCBs or other compounds.

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.

In vivo fractionation of mercury isotopes in tissues of a mammalian carnivore (Neovison vison)

The use of isotope ratios to trace Hg contamination sources in environmental compartments is now generally accepted. However, for biota and especially for mammals, it is still unknown if and/or how Hg isotopes fractionate in vivo and which tissue is most representative of the source(s) of contamination. We measured fractionation of Hg in mink (Neovison vison) tissues (fur, brain, blood, liver, kidney) collected during a controlled feeding experiment where captive mink were fed differing amounts of methylmercury. There was no significant effect of dietary MeHg concentrations on Hg fractionation in most tissues. Net fractionation of Hg, i.e., fractionation corrected for diet (δ²⁰²Hg_tissue-δ²⁰²Hg_diet) was observed in all tissues with the greatest net fractionation occurring in the mink liver (-1.39‰) and kidney (-0.95‰). Less net fractionation, occurred in the brain (-0.12‰), blood (0.38‰) and fur (0.30‰). In the absence of brain tissue, fur is a suitable proxy which is readily obtainable and can be non-lethally collected. In these mink, it appears that biochemical processes such as demethylation, contribute to significant fractionation of Hg in the liver and kidney, but not as much in the brain and fur, where transport of Hg via thiol-containing complexes may be more important.

Chemical contamination assessment in mangrove-lined Caribbean coastal systems using the oyster Crassostrea rhizophorae as biomonitor species

This paper aims to contribute to the use of mangrove cupped oyster, Crassostrea rhizophorae, as a biomonitor species for chemical contamination assessment in mangrove-lined Caribbean coastal systems. Sampling was carried out in eight localities (three in Nicaragua and five in Colombia) with different types and levels of contamination. Oysters were collected during the rainy and dry seasons of 2012-2013 and the tissue concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) were determined. Low tissue concentrations of metals (except Hg) and PAHs; moderate-to-high tissue concentrations of Hg, hexachlorocyclohexanes (HCHs), and dichlorodiphenyl-trichloroethanes (DDTs); detectable levels of chlorpyrifos, polychlorinated biphenyls (PCBs) (mainly CB28, CB118, CB138 and CB 153) and brominated diphenyl ethers 85 (BDE85); and negligible levels of musks were recorded in Nicaraguan oysters. A distinct profile of POPs was identified in Colombia, where the tissue concentrations of PCBs and synthetic musk fragrances were low to moderate, and Ag, As, Cd, Pb, and PAHs ranged from moderate to extremely high. Overall, the values recorded for HCHs, DDTs and PCBs in Nicaraguan mangrove cupped oysters greatly exceeded the reference values in tissues of C. rhizophorae from the Wider Caribbean Region, whereas only the levels of PCBs were occasionally surpassed in Colombia. Different contaminant profiles were distinguished between oysters from Nicaragua and Colombia in radar plots constructed using the main groups of contaminants (metals, PAHs, musks, PCBs, and organochlorine pesticides (OCPs)). Likewise, integrated pollution indices revealed differences in the levels of contaminants. Moreover, the profiles and levels in oyster tissues also varied with season. Thus, principal component analysis clearly discriminated Nicaraguan and Colombian localities and, especially in Colombia, seasonal trends in chemical contamination and differences amongst localities were evidenced. The geographical and environmental disparity of the studied scenarios may represent to a large extent the diversity of mangrove-lined Caribbean coastal systems and therefore the present results support the use of C. rhizophorae as suitable biomonitor species at Caribbean regional scale, where seasonal variability is a major factor controlling pollutant mobility and bioavailability.

Use of polychlorinated biphenyl and toxic equivalent concentrations in scat from mink(Neovison vison) fed fish from the upper Hudson River to predict dietary and hepatic concentrations and health effects

To evaluate health effects associated with consumption of fish contaminated with polychlorinated biphenyls (PCBs) from the upper Hudson River, farm-raised mink were fed diets containing fish collected from the river. Endpoints assessed included adult reproductive performance, offspring growth and mortality, and organ mass and pathology of adults and their offspring. Scat samples were collected from adult males at the time of necropsy and from adult females just prior to whelping. Scat samples were analyzed for PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). The present study provides the results of these analyses and compares ∑PCB and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalent (TEQ) concentrations in scat with dietary and hepatic concentrations associated with effects reported previously. Dry weight concentrations of ∑PCBs and ∑TEQs in scat generally increased with dietary concentration and reflected corresponding increases in hepatic concentrations of ∑PCBs and ∑TEQs. Maternal concentrations of ∑PCBs in scat expressed on a dry, wet, and lipid weight basis predicted to result in 50% kit mortality (LC50) were 1.0, 0.30, and 12 μg ∑PCBs/g. Concentrations of ∑PCBs in scat expressed on a dry, wet, and lipid weight basis predicted to result in 50% incidence of a previously reported jaw lesion (EC50) were 1.7, 0.48, and 24 μg ∑PCBs/g in adult females and 2.5, 0.87, and 19 μg ∑PCBs/g in adult males. Environ Toxicol Chem 2018;37:563-575. © 2017 SETAC.

Predictive meta-regressions relating mercury tissue concentrations of freshwater piscivorous mammals

Mercury (Hg) is a pollutant of global concern. Sentinel species such as river otter (Lontra canadensis) and mink (Neovison vison) are often used to monitor environmental concentrations in freshwater ecosystems. Tissue total Hg (THg) concentrations are frequently used as biomarkers of exposure. However, there is no comprehensive model relating Hg tissue concentrations in different tissues, making interstudy comparisons challenging. Our objective was to establish conversion factors relating fur, brain, liver, kidney, and muscle THg concentrations using mean concentrations and standard errors reported in the literature. We used data from more than 6000 samples, pooled across 16 studies and 96 sampling sites in North America and Europe. Sixteen regressions were derived for the river otter and mink models, which were statistically significant at a 95% confidence interval and yielded high explained variances. The models were validated using an external data set of individually measured THg tissue concentrations. The validated conversions were used to evaluate the current fur Hg screening guidelines of 20 µg/g and 30 µg/g. At both of these fur concentrations, brain concentrations are of concern for altering brain neurochemistry. We suggest a more conservative fur Hg screening guideline of 15 µg/g to protect sensitive furbearers. The conversion factors can be used to predict internal organ THg concentrations from fur measurements, eliminating the need for invasive tissue sampling. Environ Toxicol Chem 2017;36:2377-2384. © 2017 SETAC.

Organochlorine contaminants in wild mink from the lower Great Lakes basin, Canada, 1998-2006

Organochlorine contaminants were measured in livers of wild mink (Neovison vison) trapped in the lower Great Lakes basin from 1998 to 2006. To assess exposure and potential risk in mink feeding on Great Lakes biota, concentrations of contaminants were compared in mink trapped within 7.8 km of the shoreline as well as at inland sites (i.e., 8-40 km). Overall, significant spatial variation in mean hepatic concentrations of sum PCBs and seven other organochlorines was found in mink from 13 Great Lakes sites, many of which are within the Great Lakes Areas of Concern. Mean sum PCB concentrations, on a lipid weight basis, ranged from 2 μg/g in mink from inland Lake Ontario sites to 44 μg/g in mink from western Lake Erie. Concentrations of other organochlorines in mink were generally low. Mink from western Lake Erie had the highest mean cumulative organochlorine burdens dominated largely by PCBs. A significant age effect was found with 1-year-old mink having significantly higher PCB burdens than mink less than 1 year in age. With respect to published PCB threshold effect concentrations, some mink exceeded those associated with effects on reproduction and survival as well as the presence of jaw lesions. This was most consistently found in western Lake Erie where the health of populations of wild mink may be adversely affected and where no mink 2 years of age or older were collected.

Genotoxic effects of Roundup Full II® on lymphocytes of Chaetophractus villosus (Xenarthra, Mammalia): In vitro studies

In Argentina, Chaetophractus villosus has a wide distribution that overlaps with agricultural areas where soybean is the predominant crop. In such areas the pesticide Roundup Full II® (RU) is widely applied. The genotoxic effect of its active ingredient glyphosate (RU is 66.2% glyphosate) on the peripheral blood lymphocytes of C. villosus was tested over a range of concentrations (280, 420, 560, 1120 μmol/L). Culture medium without glyphosate served as negative control, while medium containing mitomycin C served as positive control. Genetic damage was characterized in terms of the percentage of cells with chromosome aberrations (CA), the mean number of sister chromatid exchanges (SCE) per cell, and the modification of cell proliferation kinetics via the calculation of the replication index. Significant increases (p < 0.0001) were seen in the CA frequency and the mean number of SCEs per cell compared to negative controls at all the RU concentrations tested. Chromatid breaks, the only form of CA observed, under the 560 μmol/L RU conditions and in presence of mitomycin C were four to five times more common than at lower concentrations, while no viable cells were seen in the 1120 μmol/L treatment. The mean number of SCEs per cell was significantly higher under the 280 μmol/L RU conditions than the 420 or 560 μmol/L RU conditions; cells cultivated in the presence of MMC also showed significantly more SCEs. All the RU concentrations tested (except in the 1120 μmol/L RU treatment [no viable cells]) induced a significant reduction in the replication index (p < 0.0001). The present results confirm the genotoxic effects of RU on C. villosus lymphocytes in vitro, strongly suggesting that exposure to RU could induce DNA damage in C. villosus wildlife.

Heavy metal concentrations in female wild mink (Neovison vison) in Sweden: Sources of variation and associations with internal organ weights

The American mink is an invasive species in Sweden, and it is legally hunted all year. Therefore, the mink is well suited as a sentinel species for environmental monitoring. In the present study female mink (n = 91) from 6 different areas in Sweden were analyzed for the concentrations of silver, cadmium, mercury and lead in liver tissue using inductively coupled plasma mass spectrometry. The wet concentrations in liver tissue were 42.6 ± 52.7 ng/g for silver, 99.5 ± 100 ng/g for cadmium, 652 ± 537 ng/g for mercury, and 196 ± 401 ng/g for lead (expressed as mean ± standard deviation). There were associations between the sample area and the concentrations of silver, lead, and mercury. The concentrations of lead and cadmium varied with season of capture and lead, cadmium, and mercury were positively associated with increasing age. Relative liver weight was positively associated with concentrations of mercury and negatively associated with lead and cadmium. Relative kidney weight was negatively associated with lead concentrations. In summary, it is of importance to take age and season of capture into account when assessing levels of heavy metals in wild mink. Also, liver and kidneys seem to be potential targets for heavy metal toxicity in wild female mink in Sweden. Environ Toxicol Chem 2017;36:2030-2035. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

European Starlings (Sturnus vulgaris) As Sentinels of Urban Air Pollution: A Comprehensive Approach from Noninvasive to Post Mortem Investigation

Urban, traffic-related air pollution remains a concern to health-care and environmental professionals, with mounting evidence connecting diverse disease conditions with exposure. Wildlife species such as European starlings (Sturnus vulgaris) cohabit urban neighborhoods and may serve as sentinels for these contaminants. In this novel approach, we use passive, personal-type air samplers to provide site-specific measurements of nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and volatile organic compounds (VOCs, such as benzene, toluene, ethylbenzene, and xylenes, or BTEX), and account for the effects of confounding environmental factors when teasing out the responses to exposure. This study examines biomarkers of exposure to predominately traffic-related, urban air contaminants in European starlings, including morphometric measurements, immunotoxicology, oxidative stress and hepatic detoxification, and analyses responses in the context of multilayered factors including year, hatch date, weather and location, confirming that this experimental approach and the selected health indicators can be used for comparing locations with different levels of contaminants.

Unbridle biomedical research from the laboratory cage

Many biomedical research studies use captive animals to model human health and disease. However, a surprising number of studies show that the biological systems of animals living in standard laboratory housing are abnormal. To make animal studies more relevant to human health, research animals should live in the wild or be able to roam free in captive environments that offer a natural range of both positive and negative experiences. Recent technological advances now allow us to study freely roaming animals and we should make use of them.

Using energy budgets to combine ecology and toxicology in a mammalian sentinel species

Process-driven modelling approaches can resolve many of the shortcomings of traditional descriptive and non-mechanistic toxicology. We developed a simple dynamic energy budget (DEB) model for the mink (Mustela vison), a sentinel species in mammalian toxicology, which coupled animal physiology, ecology and toxicology, in order to mechanistically investigate the accumulation and adverse effects of lifelong dietary exposure to persistent environmental toxicants, most notably polychlorinated biphenyls (PCBs). Our novel mammalian DEB model accurately predicted, based on energy allocations to the interconnected metabolic processes of growth, development, maintenance and reproduction, lifelong patterns in mink growth, reproductive performance and dietary accumulation of PCBs as reported in the literature. Our model results were consistent with empirical data from captive and free-ranging studies in mink and other wildlife and suggest that PCB exposure can have significant population-level impacts resulting from targeted effects on fetal toxicity, kit mortality and growth and development. Our approach provides a simple and cross-species framework to explore the mechanistic interactions of physiological processes and ecotoxicology, thus allowing for a deeper understanding and interpretation of stressor-induced adverse effects at all levels of biological organization.

Hg and Se exposure in brain tissues of striped dolphin (Stenella coeruleoalba) and bottlenose dolphin (Tursiops truncatus) from the Tyrrhenian and Adriatic Seas

In this study we analyzed Hg and Se concentrations in dolphin brain tissues of fifteen specimens of striped dolphin (Stenella coeruleoalba) and eight specimens of bottlenose dolphin (Tursiops truncatus) stranded in the Tyrrhenian and Adriatic Seas, in order to assess the toxicological risks associated with Hg exposure. High Hg concentrations were found in brain tissues of both analyzed specie (1.86-243 mg/kg dw for striped dolphin and 2.1-98.7 mg/kg dw for bottlenose dolphin), exceeding levels associated with marine mammals neurotoxicity. Althougth the results clearly suggest that the protective effects of Se against Hg toxicity occur in cetaceans' brain tissues, a molar excess of mercury with respect to selenium was found, particularly in adult specimens of Stenella coeruleoalba. On contrary, negligible neurotoxicological risks were found for Tursiops truncatus specimens, due to detoxification processes. Data obtained allowed to prove a more marked neurotoxicological risk for adult specimens of Stenella coeruleoalba in both Tyrrhenian and Adriatic Seas.

Halogenated flame retardants in bobcats from the midwestern United States

In response to the restrictions of polybrominated diphenyl ether (PBDE) flame retardants in various consumer products, alternative halogenated flame retardants have been subjected to increased use. Compared to aquatic ecosystems, relatively little information is available on the contamination of alternative flame retardants in terrestrial ecosystems, especially with regards to mammalian wildlife. In this study we used a top terrestrial carnivore, the bobcat (Lynx rufus), as a unique biomonitoring species for assessing flame retardant contamination in the Midwestern United States (U.S.) terrestrial ecosystems. Concentrations of ∑PBDEs (including all detectable PBDE congeners) ranged from 8.3 to 1920 ng/g lipid weight (median: 50.3 ng/g lw) in livers from 44 bobcats collected during 2013-2014 in Illinois. Among a variety of alternative flame retardants screened, Dechloranes (including anti- and syn-Dechlorane Plus and Dechlorane-602, 603, and 604), tetrabromo-o-chlorotoluene (TBCT), and hexabromocyclododecane (HBCD) were also frequently detected, with median concentrations of 28.7, 5.2, and 11.8 ng/g lw, respectively. Dechlorane analogue compositions in bobcats were different from what has been reported in other studies, suggesting species- or analogue-dependent bioaccumulation, biomagnification, or metabolism of Dechlorane chemicals in different food webs. Our findings, along with previously reported food web models, suggest Dechloranes may possess substantial bioaccumulation and biomagnification potencies in terrestrial mammalian food webs. Thus, attention should be given to these highly bioavailable flame retardants in future environmental biomonitoring and risk assessments in a post-PBDE era.

New computerized staging method to analyze mink testicular tissue in environmental research

Histopathology of testicular tissue is considered to be the most sensitive tool to detect adverse effects on male reproduction. When assessing tissue damage, seminiferous epithelium needs to be classified into different stages to detect certain cell damages; but stage identification is a demanding task. The authors present a method to identify the 12 stages in mink testicular tissue. The staging system uses Gata-4 immunohistochemistry to visualize acrosome development and proved to be both intraobserver-reproducible and interobserver-reproducible with a substantial agreement of 83.6% (kappa = 0.81) and 70.5% (kappa = 0.67), respectively. To further advance and objectify this method, they present a computerized staging system that identifies these 12 stages. This program has an agreement of 52.8% (kappa 0.47) with the consensus staging by 2 investigators. The authors propose a pooling of the stages into 5 groups based on morphology, stage transition, and toxicologically important endpoints. The computerized program then reached a substantial agreement of 76.7% (kappa = 0.69). The computerized staging tool uses local ternary patterns to describe the texture of the tubules and a support vector machine classifier to learn which textures correspond to which stages. The results have the potential to modernize the tedious staging process required in toxicological evaluation of testicular tissue, especially if combined with whole-slide imaging and automated tubular segmentation. Environ Toxicol Chem 2017;36:156-164. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Bioaccumulation of PCBs in a Wild North American Felid

Organohalogenated compounds (OHCs) such as polychlorinated biphenyls (PCBs) are of global concern due to their environmental persistence, bioaccumulative potential, and adverse effects on humans and wildlife. We investigated the concentrations of PCBs in the liver tissues of bobcats (Lynx rufus) sampled in Illinois during 2013. Concentrations of ∑PCBs ranged from 76.4 to 3782 ng/g lw (median 562.97 ng/g lw). Male bobcats had significantly greater concentrations of PCBs than females (p = 0.04). Ours is one of the first studies to report PCBs in a wild North American felid. We suggest that bobcats can be used as a suitable bioindicator species to monitor organohalogen contamination in terrestrial ecosystems.

Brains of Native and Alien Mesocarnivores in Biomonitoring of Toxic Metals in Europe

Mercury (Hg), lead (Pb) and cadmium (Cd) are involved in mammalian brain damage. However, little is known about Pb and Cd brain levels in wildlife that reflect the geochemical background. The aims of the study include the estimation of Hg, Pb and Cd concentrations, and the determination of relationships between these elements in the brains of 94 mesocarnivores. Road-killed or hunted animals were obtained from north-western Poland near the Polish-German border. The investigation covered the native Eurasian otter Lutra lutra, badger Meles meles, pine marten Martes martes, beech marten M. foina, European polecat Mustela putorius, red fox Vulpes vulpes, and alien species: feral and ranch American mink Neovison vison, raccoon Procyon lotor and raccoon dog Nyctereutes procyonoides. Depending on the diet and environmental pollution, the carnivore brains accumulated toxic metals in varying amounts. The highest median Hg levels (in mg/kg dry weight, dw) were found in the piscivorous Eurasian otter and feral mink (2.44 and 3.96), Pb in the omnivorous raccoon (0.47), while Cd in minks (~0.06). We indicated that Pb-based ammunition is a significant source of the element in scavengers from hunting area, and we also found a significant correlation between Pb and Cd levels in the fox brain. Finally, this study is the first to suggest background levels for brain Pb and Cd in mesocarnivores (<0.50 and <0.04 mg/kg dw, respectively).