Multilocus Sequence Typing of Mycoplasma ovipneumoniae Detected in Dall's Sheep (Ovis dalli dalli) and Caribou (Rangifer tarandus grantii) in Alaska, USA.

In 2018, Mycoplasma ovipneumoniae was detected in free-ranging caribou (Rangifer tarandus grantii) and Dall's sheep (Ovis dalli dalli) in Alaska, US. Evaluation of additional nasal swabs and archived tissues for M. ovipneumoniae suggested that this bacterium was widespread geographically and temporally in populations of both species. Multilocus sequence typing of four loci identified a single, novel, apparently stable strain type of M. ovipneumoniae in 11 Dall's sheep and 15 caribou in multiple populations across Alaska sampled over a period of 15 yr (2004-19). This strain type differs from those detected to date from wild or domestic sheep (Ovis aries) or goats (Capra aegagrus hircus) tested in Alaska or the lower 48 states. Although the population health implications of this strain are unknown, it has not been associated with population-wide mortality events. The presence of this strain does not decrease the potential risk from the introduction of a pathogenic M. ovipneumoniae strain associated with severe disease in other wildlife populations; therefore, continued monitoring for signs of disease and additional strains is important.

LABORATORY CONCORDANCE STUDY FOR THE MOLECULAR DETECTION OF MYCOPLASMA OVIPNEUMONIAE.

As part of a respiratory pathogen survey of Alaska wildlife, we conducted a concordance study to assess Mycoplasma ovipneumoniae detection among three different PCR assays using a total of 346 nasal swabs sampled from four species (Dall's sheep, Ovis dalli dalli; mountain goats, Oreamnos americanus; caribou, Rangifer tarandus granti; and moose, Alces alces gigas), and two taxonomic subfamilies (Bovidae subfamily Caprinae and Cervidae subfamily Capreolinae). A federal research laboratory performed two PCR assays (LM40 and intergenic spacer region [IGS]), and a state diagnostic laboratory performed the third (universal Mycoplasma [UM]). Overall concordance was good, ranging from 93% to 99%, which was probably a result of low detection rate of M. ovipneumoniae. Due to differences in positive agreement, the quality of concordance between LM40 and both IGS and UM was considered fair. However, the quality of concordance between IGS and UM was excellent. All three PCR methods detected M. ovipneumoniae in a non-Caprinae species (caribou), and the LM40-PCR assay also detected M. ovipneumoniae in additional Caprinae species. The LM40-PCR assay detected M. ovipneumoniae in a larger number of samples than did the other two assays (IGS, UM). Because of potential differences in detection rates, it is critical to consider test parameters when evaluating a host population for the presence of M. ovipneumoniae.

Variation in bioaccumulation of persistent organic pollutants based on octanol-air partitioning: Influence of respiratory elimination in marine species.

Risk assessments of persistent organic pollutants (POPs) are often based on octanol-water (KOW) partitioning dynamics and may not adequately reflect bioaccumulation in air-breathing organisms. It has been suggested that compounds with low KOW and high octanol-air partitioning (KOA) coefficients have the potential to bioaccumulate in air-breathing organisms, including marine mammals. Here we evaluate differences in concentrations of POPs for two trophically matched Arctic species, spotted seal (Phoca largha) and sheefish (Stenodus leucichthys). We compared concentrations of 108 POPs in matched tissues (liver and muscle) across three ranges of KOW. We found a significant positive correlation between POP concentration and log KOA in spotted seal tissues for low log KOW compounds (log KOW <5.5, p<0.05). This provides further evidence for empirical models and observed bioaccumulation patterns in air-breathing organisms, and highlights the potential for bioaccumulation of these compounds in Arctic marine mammals.

Mercury and methylmercury distribution in tissues of sculpins from the Bering Sea.

Fish skeletal muscle is often used to monitor mercury concentrations and is used by regulatory agencies to develop fish consumption advisories. However, the distribution of mercury species (MeHg+ and THg) in muscle tissue and other organs is not well understood in a number of fish species. Here we evaluate the spatial distribution of THg and MeHg+ in skeletal muscle and internal organs (heart, liver, and kidney) of 19 sculpin representing three species: Myoxocephalus scorpius (shorthorn sculpin n = 13), Myoxocephalus jaok (plain sculpin, n = 4), and Megalocottus platycephalus (belligerent sculpin, n = 2). Four subsamples of muscle were taken along the lateral aspect of each fish, from muscle A (cranial) to muscle D (caudal). Using Games-Howell post hoc procedure to compare mean concentrations of all tissues, muscle samples were significantly different from internal organs, although there was no difference between muscle-sampling locations. THg concentrations (ww) were higher in muscle (muscle A through D mean ± SD, 0.30 ± 0.19 mg/kg) than that in heart (0.06 ± 0.05 mg/kg), kidney (0.08 ± 0.06 mg/kg), and liver (0.09 ± 0.08 mg/kg). Percent MeHg+ decreased with age in both skeletal muscle and organs (p < 0.05). In contrast to some previous reports for other fish species, this study found significantly higher THg concentrations in muscle than in the liver. This study highlights the importance of using muscle samples when evaluating potential Hg exposure in risk assessments for piscivorous wildlife and human populations, and assumptions related to organ mercury concentrations should be examined with care.

Mercury concentrations in hair from neonatal and juvenile Steller Sea Lions (Eumetopias jubatus): implications based on age and region in this northern Pacific marine sentinel piscivore.

Mercury is a global contaminant of concern for the fetus and the neonate of piscivores. Methylmercury, produced within marine ecosystems, is of particular concern as a readily absorbed neurotoxicant transported across the blood brain barrier and transplacentally. In the North Pacific Ocean, Steller sea lions are broadly distributed apex predators and, as such, integrate complex food webs and the associated exposure and possible adverse effects of toxic and infectious agents. Hair, including lanugo, was examined using regional and age groupings to assess mercury concentrations in young Alaskan Steller sea lions. The highest concentrations of mercury occurred in the youngest animals, likely via in utero exposure. Based on the adverse developmental outcomes of methylmercury toxicity this specific cohort is of concern. Regionally, higher concentrations of mercury were observed in the endangered western population of Steller sea lions and mirrored patterns observed in human biomonitoring studies of Alaskan coastal communities. These data have broader implications with respect to human and ecosystem health as Steller sea lions rely on similar prey species and foraging areas as those targeted by commercial fisheries and subsistence users and are therefore valuable sentinels of marine ecosystem health.

Toxicokinetics of mercury in blood compartments and hair of fish-fed sled dogs.

BACKGROUND: Understanding mercury (Hg) distribution in blood and the importance of hair as an excretory pathway is critical for evaluating risk from long term dietary Hg exposure. The major objective of this study was to characterize changes in total Hg concentrations in specific blood compartments and hair over time due to long term piscivory. METHODS: Eight sled dogs (Canis lupus familiaris) were fed either a fish and kibble diet (n = 4), or a fish-free control diet (n = 4) for 12 weeks. Concentrations of Hg were monitored throughout the exposure period, and for 10 weeks post exposure, until Hg concentrations in all blood compartments of one of the exposed dogs dropped below detection limit. Additionally, foreleg hair was sampled during acclimation and weeks 0 and 12. RESULTS: Hg was detected primarily in whole blood and packed cells, although it was sporadically detected at low concentrations in plasma and serum in two of the fish fed dogs. Dogs ingested an estimated average of 13.4 ± 0.58 µg Hg per kg body weight per day. Hg was detectable in whole blood and packed cells within a week of exposure. Detected concentrations continued to rise until plateauing at approximately 3-6 weeks of exposure at a mean of 9.2 ± 1.97 ng/g (ppb) in whole blood. Hg concentration decreased post exposure following 1st order elimination. The mean half-life (t1/2) in whole blood for Hg was 7 weeks. Mean Hg in hair for the fish-fed dogs at week 12 was 540 ± 111 ppb and was significantly greater (about 7-fold) than the Hg hair concentration for the control dogs. The hair to blood ratio for Hg in fish-fed dogs was 59.0 ± 7.6:1. CONCLUSIONS: This study found the sled dog model to be an effective method for investigating and characterizing blood Hg distribution (whole blood, serum, plasma, packed cells) and toxicokinetics associated with a piscivorous diet, especially for Hg-exposed fur bearing mammals (such as polar bears). Although hair excretion and hair to blood Hg ratios were not similar to human concentrations and ratios, the sled dog toxicokinetics of Hg in blood, was more similar to that of humans than traditional laboratory animals (such as the rat).

Streptococcus phocae isolated from a spotted seal (Phoca largha) with pyometra in Alaska.

A spotted seal harvested by subsistence hunters in Kotzebue Sound, Alaska (USA), showed a grossly enlarged uterus and associated lymph nodes. Streptococcus phocae was isolated from the purulent uterine discharge. Histopathologic examination revealed inflammation that was limited to the uterine mucosa. Lymph nodes draining the affected organ were reactive but no evidence of active infection was found in the lymph nodes. This report is the first Streptococcus phocae isolated from spotted seals as well as the first report of pyometra as the main pathologic finding associated with this pathogen. Isolation of this pathogen from Alaska expands the reported range to arctic pinnipeds. Zoonotic potential remains unknown.

Agrochemicals increase trematode infections in a declining amphibian species.

Global amphibian declines have often been attributed to disease, but ignorance of the relative importance and mode of action of potential drivers of infection has made it difficult to develop effective remediation. In a field study, here we show that the widely used herbicide, atrazine, was the best predictor (out of more than 240 plausible candidates) of the abundance of larval trematodes (parasitic flatworms) in the declining northern leopard frog Rana pipiens. The effects of atrazine were consistent across trematode taxa. The combination of atrazine and phosphate--principal agrochemicals in global corn and sorghum production--accounted for 74% of the variation in the abundance of these often debilitating larval trematodes (atrazine alone accounted for 51%). Analysis of field data supported a causal mechanism whereby both agrochemicals increase exposure and susceptibility to larval trematodes by augmenting snail intermediate hosts and suppressing amphibian immunity. A mesocosm experiment demonstrated that, relative to control tanks, atrazine tanks had immunosuppressed tadpoles, had significantly more attached algae and snails, and had tadpoles with elevated trematode loads, further supporting a causal relationship between atrazine and elevated trematode infections in amphibians. These results raise concerns about the role of atrazine and phosphate in amphibian declines, and illustrate the value of quantifying the relative importance of several possible drivers of disease risk while determining the mechanisms by which they facilitate disease emergence.

Prevalence of skeletal and eye malformations in frogs from north-central United States: estimations based on collections from randomly selected sites.

Skeletal malformation rates for several frog species were determined in a set of randomly selected wetlands in the north-central USA over three consecutive years. In 1998, 62 sites yielded 389 metamorphic frogs, nine (2.3%) of which had skeletal or eye malformations. A subset of the original sites was surveyed in the following 2 yr. In 1999, 1,085 metamorphic frogs were collected from 36 sites and 17 (1.6%) had skeletal or eye malformations, while in 2000, examination of 1,131 metamorphs yielded 16 (1.4%) with skeletal or eye malformations. Hindlimb malformations predominated in all three years, but other abnormalities, involving forelimb, eye, and pelvis were also found. Northern leopard frogs (Rana pipiens) constituted the majority of collected metamorphs as well as most of the malformed specimens. However, malformations were also noted in mink frogs (R. septentrionalis), wood frogs (R. sylvatica), and gray tree frogs (Hyla spp.). The malformed specimens were found in clustered sites in all three years but the cluster locations were not the same in any year. The malformation rates reported here are higher than the 0.3% rate determined for metamorphic frogs collected from similar sites in Minnesota in the 1960s, and thus, appear to represent an elevation of an earlier baseline malformation rate.