Geology topics

Lizabeth Bowen

Publications and source records attributed to Lizabeth Bowen.

At least 37 records · Page 2Linked to original sources

USGS2020

Monitoring nearshore ecosystem health using Pacific razor clams (Siliqua patula) as an indicator species

An emerging approach to ecosystem monitoring involves the use of physiological biomarker analyses in combination with gene transcription assays. For the first time, we employed these tools to evaluate the Pacific razor clam ( Siliqua patula ), which is important both economically and ecologically, as a bioindicator species in the northeast Pacific. Our objectives were to (1) develop biomarker and gene transcription assays with which to monitor the health of the Pacific razor clam, (2) acquire baseline biomarker and gene transcription reference ranges for razor clams, (3) assess the relationship between physiological and gene transcription assays and (4) determine if site-level differences were present. Pacific razor clams were collected in July 2015 and 2016 at three sites within each of two national parks in southcentral Alaska. In addition to determining reference ranges, we found differences in biomarker assay and gene transcription results between parks and sites which indicate variation in both large-scale and local environmental conditions. Our intent is to employ these methods to evaluate Pacific razor clams as a bioindicator of nearshore ecosystem health. Links between the results of the biomarker and gene transcription assays were observed that support the applicability of both assays in ecosystem monitoring. However, we recognize the need for controlled studies to examine the range of responses in physiology and gene transcripts to different stressors. sors.

Alaska↗

USGS2020

Evidence of prevalent heat stress in Yukon River Chinook salmon

Migrating adult Pacific salmon ( Oncorhynchus spp.) are sensitive to warm water (>18 °C), with a range of consequences from decreased spawning success to early mortality. We examined the proportion of Yukon River Chinook salmon ( O. tshawytscha ) exhibiting evidence of heat stress to assess the potential that high temperatures contribute to freshwater adult mortality in a northern Pacific salmon population. Water temperatures greater than 18 °C have occurred almost annually in the Yukon River and correspond with low population abundance since the 1990s. Using gene transcription products and heat shock protein 70 biomarkers validated by field experiment, we identified heat stress in half of Chinook salmon examined (54%, n = 477) across three mainstem locations and three tributaries in 2016–2017. Biomarkers tracked wide variation in water temperature (14–23 °C) within a tributary. The proportion of salmon with heat stress differed between years at four of the six locations, with more prevalent heat stress in the warmer year. This work demonstrates that warming water temperatures are currently affecting northern populations of Pacific salmon.

Alaska↗

USGS2019

Physiological and gene transcription assays to assess responses of mussels to environmental changes

Coastal regions worldwide face increasing management concerns due to natural and anthropogenic forces that have the potential to significantly degrade nearshore marine resources. The goal of our study was to develop and test a monitoring strategy for nearshore marine ecosystems in remote areas that are not readily accessible for sampling. Mussel species have been used extensively to assess ecosystem vulnerability to multiple, interacting stressors. We sampled bay mussels ( Mytilus trossulus ) in 2015 and 2016 from six intertidal sites in Lake Clark and Katmai National Parks and Preserves, in south-central Alaska. Reference ranges for physiological assays and gene transcription were determined for use in future assessment efforts. Both techniques identified differences among sites, suggesting influences of both large-scale and local environmental factors and underscoring the value of this combined approach to ecosystem health monitoring.

Alaska↗

USGS2019

Southern sea otter (Enhydra lutris nereis) population biology at Big Sur and Monterey, California --Investigating the consequences of resource abundance and anthropogenic stressors for sea otter recovery

The range of the southern sea otter ( Enhydra lutris nereis ) spans most of the central California coast from Half Moon Bay to Gaviota. Some coastal areas within this range are heavily developed and highly impacted by humans, while other areas are wild and largely pristine. Determining the relative importance of food resource abundance, environmental conditions, and anthropogenic increases in pathogens and pollutants to population change in sea otters is critical to understanding limitations to population growth. To investigate the causal links between the sluggish population growth of sea otters in central California and factors that could be driving variation in survival and reproduction, we designed a study to compare two distinct subpopulations—one in an area of low human impact (Big Sur) and one in an area of high human impact (Monterey). Between 2008 and 2011, the U.S. Geological Survey and collaborators conducted a telemetry-based study of sea otters at these two locations. The results of this study were not consistent with the hypothesis that sea otters adjacent to human population centers (Monterey) experience higher exposure to pollutants and pathogens than those in lower impacted areas (Big Sur). In fact, based on serological analysis, female sea otters from Big Sur showed higher exposure rates to Toxoplasma gondii than did female otters from Monterey, while domoic acid exposure appeared to be similar at both sites. Gene expression (specifically transcription) analysis did not indicate any consistent differences between the two populations that would have suggested a response to pathogen or toxin exposure, although there were temporal changes in gene transcription for sea otters at Big Sur following potential exposure to run-off from wildfires that occurred during the study. Together, these metrics suggest that variation in exposure to environmental stressors occurred, but patterns were not clearly attributable to differences in human population densities or land-use patterns. When compared to Monterey, sea otters in Big Sur spent more time feeding, had a higher degree of dietary specialization, were in poorer body condition, and had lower survival rates (both pups and adults). Together, these metrics suggest that otters at Big Sur had greater nutritional stress, consistent with lower per-capita resource abundance. Overall, study results indicate that density-dependent population regulation, mediated by per-capita resource abundance, is the most significant factor currently limiting population growth in the center part of the range. Additionally, spatial and temporal variation in environmental and anthropogenic stressors also can affect sea otter health, although patterns of variation are complex and are not simply a function of proximity to human populations. We also found that exposure to environmental stressors (either natural or anthropogenic in origin) often is associated with resource limitation. Finally, our results indicate that sea otter populations are structured at relatively small spatial scales, and the processes that regulate population abundance (including density-dependent resource abundance) also occur at these smaller, more local scales.

California↗

USGS2019

Complex immune responses and molecular reactions to pathogens and disease in a desert reptile (Gopherus agassizii)

Immune function plays an important role in an animal's defense against infectious disease. In reptiles, immune responses may be complex and counterintuitive, and diagnostic tools used to identify infection, such as induced antibody responses are limited. Recent studies using gene transcription profiling in tortoises have proven useful in identifying immune responses to various intrinsic and extrinsic stressors. As part of a larger experiment with Mojave desert tortoises ( Gopherus agassizii ), we facilitated the transmission of the pathogenic bacteria, Mycoplasma agassizii (Myag), to naïve adults and measured innate and induced immune reactions over time. Specifically, we evaluated clinical condition, presence of Myag in the nasal/oral cavity, induced antibody responses specific to Myag, and measured molecular reactions (gene transcript profiles) in 15 captive tortoises classified as naïve, exposed, or infected and 14 wild tortoises for comparison. Myag was confirmed inside the nasal/oral cavity in exposed tortoises within 30–60 days of introduction to infected animals, yet we did not detect Myag specific induced antibody responses in these individuals until 420–595 days post exposure. Surprisingly, we found no overall differences in the gene transcript profiles between our experimental treatment groups throughout this study. This work highlights the complexities in assessing immune function and diagnosing pathogen related infections in tortoises and other reptiles.

Ecology and Evolution↗

USGS2018

MHC class II DRB diversity predicts antigen recognition and is associated with disease severity in California sea lions naturally infected with Leptospira interrogans

We examined the associations between California sea lion MHC class II DRB (Zaca-DRB) configuration and diversity, and leptospirosis. As Zaca-DRB gene sequences are involved with antigen presentation of bacteria and other extracellular pathogens, we predicted that they would play a role in determining responses to these pathogenic spirochaetes. Specifically, we investigated whether Zaca-DRB diversity (number of genes) and configuration (presence of specific genes) explained differences in disease severity, and whether higher levels of Zaca-DRB diversity predicted the number of specific Leptospira interrogans serovars that a sea lion's serum would react against. We found that serum from diseased sea lions with more Zaca-DRB loci reacted against a wider array of serovars. Specific Zaca-DRB loci were linked to reactions with particular serovars. Interestingly, sea lions with clinical manifestation of leptospirosis that had higher numbers of Zaca-DRB loci were less likely to recover from disease than those with lower diversity, and those that harboured Zaca-DRB.C or –G were 4.5 to 5.3 times more likely to die from leptospirosis, regardless of the infective serovars. We propose that for leptospirosis, a disadvantage of having a wider range of antigen presentation might be increased disease severity due to immunopathology. Ours is the first study to examine the importance of Zaca-DRB diversity for antigen detection and disease severity following natural exposure to infective leptospires.

California↗

USGS2018

Genetics

In the current context of environmental changes, it is easy to see how extrinsic factors, such as shifts in sea surface temperature, food availability and accumulation of pollutants, can impact the health of marine mammals. However, intrinsic factors, including the genetic constitution of an individual, are also largely responsible for shaping health, particularly in terms of immune system effectiveness. In the previous edition of this book, the chapter on genetics thoroughly addressed the techniques available for identification of species, populations, stocks and individuals, studying social organization, and determining the relationships among individuals in a group. We have written the current chapter with an emphasis on how each individual’s genetic constitution and the prevalence of particular genetic variants is relevant to marine mammal health and disease. The chapter first presents a brief conceptual framework for understanding how genetics shape health and disease. We next outline common genetic techniques and current tools and technologies that are emerging in marine mammal health studies. Finally, the scope, pitfalls and limitations of these tools are discussed.

Book chapter↗

USGS2018

Development and utility of a gene transcription panel for desert bighorn sheep (Ovis canadensis nelsoni)

Respiratory disease is a key factor impacting the success of the ongoing conservation and recovery of wild sheep populations (WAFWA 2017). Although the primary pathogens involved in the bighorn sheep pneumonia complex have been identified, the wide variability in herd response following infection is not well understood (Cassirer et al. 2018). The response of populations infected with Mycoplasma ovipneumoniae has been variable, from minimal to extensive herd mortality followed by years to decades of either poor lamb recruitment or little expression of disease and minimal impact on lamb survival (Coggins and Mathews 1992, Jorgenson et al. 1997, Cassirer et al. 2018). This variation is thought to be caused by differences in pathogen virulence, intrinsic or extrinsic factors that impact individual or herd immunity, including lungworm ( Protostrongylus spp.) or mite ( Psoroptes ovis ) infections, malnutrition, inbreeding, harsh weather conditions, or stress associated with overcrowding (Risenhoover et al. 1988, Bailey 1990, Jones and Worley 1994, Monello et al. 2001). Although substantial management strategies have been implemented, they have been ineffective in halting the spread of the epizootic (Cassirer et al. 2018).

Conference Paper↗

USGS2017

Using gene transcription to assess ecological and anthropological stressors in brown bears

Increasingly, population- and ecosystem-level health assessments are performed using sophisticated molecular tools. Advances in molecular technology enable the identification of synergistic effects of multiple stressors on the individual physiology of different species. Brown bears ( Ursus arctos ) are an apex predator; thus, they are ideal candidates for detecting potentially ecosystem-level systemic perturbations using molecular-based tools. We used gene transcription to analyze 130 brown bear samples from three National Parks and Preserves in Alaska. Although the populations we studied are apparently stable in abundance and exist within protected and intact environments, differences in transcript profiles were noted. The most prevalent differences were among locations. The transcript patterns among groups reflect the influence of environmental factors, such as nutritional status, disease, and xenobiotic exposure. However, these profiles also likely represent baselines for each unique environment by which future measures can be made to identify early indication of population-level changes due to, for example, increasing Arctic temperatures. Some of those environmental changes are predicted to be potentially positive for brown bears, but other effects such as the manifestation of disease or indirect effects of oceanic acidification may produce negative impacts.

Alaska↗

USGS2017

An evaluation of the efficacy of using environmental DNA (eDNA) to detect giant gartersnakes (Thamnophis gigas)

Detecting populations of rare or cryptic species is essential for their conservation. For species like giant gartersnakes ( Thamnophis gigas ), conventional survey methods can be expensive and inefficient. These sampling difficulties might be overcome by modern techniques that detect deoxyribonucleic acid (DNA) shed by organisms into the environment (eDNA). We evaluated the efficacy of detecting giant gartersnake eDNA in water samples from the laboratory and at locations with known giant gartersnake populations in the Sacramento Valley of California, and failed to detect giant gartersnake DNA in most laboratory and all field samples. Aspects of giant gartersnake biology—such as highly keratinized skin and spending extensive time in the terrestrial environment, as well as hot, sunny, and turbid conditions in wetlands and canals of the Sacramento Valley—likely contributed to low detection probabilities. Although detection of eDNA shows promise under many conditions, further development is needed before sampling for eDNA is a viable option for detecting giant gartersnake populations.

California↗

USGS2017

Coupling gene-based and classic veterinary diagnostics improves interpretation of health and immune function in the Agassiz’s desert tortoise (Gopherus agassizii)

The analysis of blood constituents is a widely used tool to aid in monitoring of animal health and disease. However, classic blood diagnostics (i.e. hematologic and plasma biochemical values) often do not provide sufficient information to determine the state of an animal’s health. Field studies on wild tortoises and other reptiles have had limited success in drawing significant inferences between blood diagnostics and physiological and immunological condition. However, recent research using gene transcription profiling in the threatened Mojave desert tortoise ( Gopherus agassizii ) has proved useful in identifying immune or physiologic responses and overall health. To improve our understanding of health and immune function in tortoises, we evaluated both standard blood diagnostic (body condition, hematologic, plasma biochemistry values, trace elements, plasma proteins, vitamin A levels) and gene transcription profiles in 21 adult tortoises (11 clinically abnormal; 10 clinically normal) from Clark County, NV, USA. Necropsy and histology evaluations from clinically abnormal tortoises revealed multiple physiological complications, with moderate to severe rhinitis or pneumonia being the primary cause of morbidity in all but one of the examined animals. Clinically abnormal tortoises had increased transcription for four genes (SOD, MyD88, CL and Lep), increased lymphocyte production, biochemical enzymes and organics, trace elements of copper, and decreased numbers of leukocytes. We found significant positive correlations between increased transcription for SOD and increased trace elements for copper, as well as genes MyD88 and Lep with increased inflammation and microbial insults. Improved methods for health assessments are an important element of monitoring tortoise population recovery and can support the development of more robust diagnostic measures for ill animals, or individuals directly impacted by disturbance.

Conservation Physiology↗

USGS2017

Southern sea otter range expansion and habitat use in the Santa Barbara Channel, California

The re-colonization of the Santa Barbara channel by sea otters brings these ESA-listed marine mammals closer to active oil and gas production facilities, shipping lanes and naturally occurring oil and gas seeps. However, the degree to which sea otters may actually be affected by human-caused oil spills or exposure to natural oil seeps is currently unknown. Between 2012 and 2014, the U.S. Geological Survey and collaborating agencies conducted a telemetry-based study of sea otters in Santa Barbara channel, in order to provide critical information for resource managers (specifically the Bureau of Ocean Energy Management, henceforth BOEM, and the U.S. Fish and Wildlife Service, henceforth USFWS) about the spatial ecology, population status, and potential population threats to sea otters in Santa Barbara Channel, with particular reference to exposure to manmade structures and sources of oil and natural gas. Analysis of spatial monitoring data using a Bayesian-based synoptic model allowed for description of sea otter home ranges, identification of hot-spots of use, and insights into habitat selection behavior by male and female sea otters. Important findings included the deeper modal depth preferred by males versus females, strong preferences by both sexes for areas with persistent kelp canopy, and greater use of soft-sediment areas by males. The synoptic model also provided the ability to predict population-level density distribution for each sex in new habitats: by calculating the value of these probability density distributions at the known locations of natural seeps, we were able to identify those seeps with higher potential for sea otter encounters. The relative probability of occurrence at locations near to some seeps was sufficiently high (about 1% likelihood of occurrence for some of our study animals) that one would anticipate occasional encounters. Data on male and female survival, reproductive success, activity budgets, and body condition all indicated that sea otters in Santa Barbara Channel are not resource limited, and thus we would expect to see continued strong population growth in this area. However, the principal cause of death for study animals was lethal bites by white sharks, suggesting that shark bite mortality represents the single biggest threat to continued population growth in the Santa Barbara Channel.

California↗

USGS2017

Gene transcription patterns in response to low level petroleum contaminants in Mytilus trossulus from field sites and harbors in southcentral Alaska

The 1989 Exxon Valdez oil spill damaged a wide range of natural resources, including intertidal communities, and post-spill studies demonstrated acute and chronic exposure and injury to an array of species. Standard toxicological methods to evaluate petroleum contaminants have assessed tissue burdens, with fewer assays providing indicators of health or physiology, particularly when contaminant levels are low and chronic. Marine mussels are a ubiquitous and crucial component of the nearshore environment, and new genomic technologies exist to quantify molecular responses of individual mussels to stimuli, including exposure to polycyclic aromatic hydrocarbons (PAHs). We used gene-based assays of exposure and physiological function to assess chronic oil contamination using the Pacific blue mussel, Mytilus trossulus . We developed a diagnostic gene transcription panel to investigate exposure to PAHs and other contaminants and its effects on mussel physiology and health. During 2012–2015, we analyzed mussels from five field sites in western Prince William Sound, Alaska, with varying oil histories from the 1989 Exxon Valdez oil spill, and from three boat harbors in the area. Gene transcription patterns of mussels from harbors were consistent with elevated exposure to PAHs or other contaminants, whereas transcription patterns of mussels sampled from shorelines in areas affected by the oil spill indicated no PAH exposure.

Alaska↗

USGS2016

Negative impacts of invasive plants on conservation of sensitive desert wildlife

Habitat disturbance from development, resource extraction, off-road vehicle use, and energy development ranks highly among threats to desert systems worldwide. In the Mojave Desert, United States, these disturbances have promoted the establishment of nonnative plants, so that native grasses and forbs are now intermixed with, or have been replaced by invasive, nonnative Mediterranean grasses. This shift in plant composition has altered food availability for Mojave Desert tortoises ( Gopherus agassizii ), a federally listed species. We hypothesized that this change in forage would negatively influence the physiological ecology, immune competence, and health of neonatal and yearling tortoises. To test this, we monitored the effects of diet on growth, body condition, immunological responses (measured by gene transcription), and survival for 100 captive Mojave tortoises. Tortoises were assigned to one of five diets: native forbs, native grass, invasive grass, and native forbs combined with either the native or invasive grass. Tortoises eating native forbs had better body condition and immune functions, grew more, and had higher survival rates (>95%) than tortoises consuming any other diet. At the end of the experiment, 32% of individuals fed only native grass and 37% fed only invasive grass were found dead or removed from the experiment due to poor body conditions. In contrast, all tortoises fed either the native forb or combined native forb and native grass diets survived and were in good condition. Health and body condition quickly declined for tortoises fed only the native grass ( Festuca octoflora ) or invasive grass ( Bromus rubens ) with notable loss of fat and muscle mass and increased muscular atrophy. Bromus rubens seeds were found embedded in the oral mucosa and tongue in most individuals eating that diet, which led to mucosal inflammation. Genes indicative of physiological, immune, and metabolic functions were transcribed at lower levels for individuals fed B. rubens , indicating potential greater susceptibility to disease or other health-related problems. This study highlights the negative indirect effects of invasive grasses, such as red brome, in desert ecosystems, and provides definitive evidence of a larger negative consequence to health, survival, and ultimately population recruitment for Mojave Desert tortoises than previously understood.

Ecosphere↗

USGS2016

Cessation of oil exposure in harlequin ducks after the Exxon Valdez oil spill: Cytochrome P4501A biomarker evidence

The authors quantified hepatic hydrocarbon-inducible cytochrome P4501A (CYP1A) expression, as ethoxyresorufin-O-deethylase (EROD) activity, in wintering harlequin ducks ( Histrionicus histrionicus ) captured in Prince William Sound, Alaska (USA), during 2011, 2013, and 2014 (22–25 yr following the 1989 Exxon Valdez oil spill). Average EROD activity was compared between birds from areas oiled by the spill and those from nearby unoiled areas. The present study replicated studies conducted from 1998 to 2009 demonstrating that harlequin ducks using areas oiled in 1989 had elevated EROD activity, indicative of oil exposure, up to 2 decades post spill. In the present study, it was found that average EROD activity during March 2011 was significantly higher in wintering harlequin ducks captured in oiled areas relative to unoiled areas, which the authors interpret to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 22 yr after the original spill. However, the 2011 results also indicated reductions in exposure relative to previous years. Average EROD activity in birds from oiled areas was approximately 2 times that in birds from unoiled areas in 2011, compared with observations from 2005 to 2009, in which EROD activity was 3 to 5 times higher in oiled areas. It was also found that average EROD activity during March 2013 and March 2014 was not elevated in wintering harlequin ducks from oiled areas. The authors interpret these findings to indicate that exposure of harlequin ducks to residual Exxon Valdez oil abated within 24 yr after the original spill. The present study finalizes a timeline of exposure, extending over 2 decades, for a bird species thought to be particularly vulnerable to oil contamination in marine environments

Alaska↗

USGS2016

Gene transcript profiling in sea otters post-Exxon Valdez oil spill: A tool for marine ecosystem health assessment

Using a panel of genes stimulated by oil exposure in a laboratory study, we evaluated gene transcription in blood leukocytes sampled from sea otters captured from 2006–2012 in western Prince William Sound (WPWS), Alaska, 17–23 years after the 1989 Exxon Valdez oil spill (EVOS). We compared WPWS sea otters to reference populations (not affected by the EVOS) from the Alaska Peninsula (2009), Katmai National Park and Preserve (2009), Clam Lagoon at Adak Island (2012), Kodiak Island (2005) and captive sea otters in aquaria. Statistically, sea otter gene transcript profiles separated into three distinct clusters: Cluster 1, Kodiak and WPWS 2006–2008 (higher relative transcription); Cluster 2, Clam Lagoon and WPWS 2010–2012 (lower relative transcription); and Cluster 3, Alaska Peninsula, Katmai and captive sea otters (intermediate relative transcription). The lower transcription of the aryl hydrocarbon receptor (AHR), an established biomarker for hydrocarbon exposure, in WPWS 2010–2012 compared to earlier samples from WPWS is consistent with declining hydrocarbon exposure, but the pattern of overall low levels of transcription seen in WPWS 2010–2012 could be related to other factors, such as food limitation, pathogens or injury, and may indicate an inability to mount effective responses to stressors. Decreased transcriptional response across the entire gene panel precludes the evaluation of whether or not individual sea otters show signs of exposure to lingering oil. However, related studies on sea otter demographics indicate that by 2012, the sea otter population in WPWS had recovered, which indicates diminishing oil exposure.

Alaska↗

USGS2016

Longitudinal evaluation of leukocyte transcripts in killer whales ( Orcinus Orca )

Early identification of illness and/or presence of environmental and/or social stressors in free-ranging and domestic cetaceans is a priority for marine mammal health care professionals. Incorporation of leukocyte gene transcript analysis into the diagnostic tool kit has the potential to augment classical diagnostics based upon ease of sample storage and shipment, inducible nature and well-defined roles of transcription and associated downstream actions. Development of biomarkers that could serve to identify “insults” and potentially differentiate disease etiology would be of great diagnostic value. To this end, a modest number of peripheral blood leukocyte gene transcripts were selected for application to a domestic killer whale population with a focus on broad representation of inducible immunologically relevant genes. Normalized leukocyte transcript values, longitudinally acquired from 232 blood samples derived from 26 clinically healthy whales, were not visibly influenced temporally nor by sex or the specific Park in which they resided. Stability in leukocyte transcript number during periods of health enhances their potential use in diagnostics through identification of outliers. Transcript levels of two cytokine genes, IL-4 and IL-17, were highly variable within the group as compared to the other transcripts. IL-4 transcripts were typically absent. Analysis of transcript levels on the other genes of interest, on an individual animal basis, identified more outliers than were visible when analyzed in the context of the entire population. The majority of outliers (9 samples) were low, though elevated transcripts were identified for IL-17 from 2 animals and one each for Cox-2 and IL-10. The low number of outliers was not unexpected as sample selection was intentionally directed towards animals that were clinically healthy at the time of collection. Outliers may reflect animals experiencing subclinical disease that is transient and self-limiting. The immunologic knowledge derived from longitudinal immunologic studies in killer whales, as was the target of the present study, has the potential to improve diagnostics and health related decision making for this and other domestic and free-ranging cetacean species.

Veterinary Immunology and Immunopathology↗

USGS2015

Gene transcription in polar bears ( Ursus maritimus ) from disparate populations

Polar bears in the Beaufort (SB) and Chukchi (CS) Seas experience different environments due primarily to a longer history of sea ice loss in the Beaufort Sea. Ecological differences have been identified as a possible reason for the generally poorer body condition and reproduction of Beaufort polar bears compared to those from the Chukchi, but the influence of exposure to other stressors remains unknown. We use molecular technology, quantitative PCR, to identify gene transcription differences among polar bears from the Beaufort and Chukchi Seas as well as captive healthy polar bears. We identified significant transcriptional differences among a priori groups (i.e., captive bears, SB 2012, SB 2013, CS 2013) for ten of the 14 genes of interest (i.e., CaM, HSP70, CCR3, TGFβ, COX2, THRα, T-bet, Gata3, CD69, and IL17); transcription levels of DRβ, IL1β, AHR, and Mx1 did not differ among groups. Multivariate analysis also demonstrated separation among the groups of polar bears. Specifically, we detected transcript profiles consistent with immune function impairment in polar bears from the Beaufort Sea, when compared with Chukchi and captive polar bears. Although there is no strong indication of differential exposure to contaminants or pathogens between CS and SB bears, there are clearly differences in important transcriptional responses between populations. Further investigation is warranted to refine interpretation of potential effects of described stress-related conditions for the SB population.

Polar Biology↗