The emergence of the calvarial hematopoietic niche in health and disease.

The diploë region of skull has recently been discovered to act as a myeloid cell reservoir to the underlying meninges. The presence of ossified vascular channels traversing the inner skull of cortex provides a passageway for the cells to traffic from the niche, and CNS-derived antigens traveling through cerebrospinal fluid in a perivascular manner reaches the niche to signal myeloid cell egress. This review will highlight the recent findings establishing this burgeoning field along with the known role this niche plays in CNS aging and disease. It will further highlight the anatomical routes and physiological properties of the vascular structures these cells use for trafficking, spanning from skull to brain parenchyma.

SCRAP: a bioinformatic pipeline for the analysis of small chimeric RNA-seq data.

MicroRNAs (miRNAs) are small non-coding RNAs (sncRNAs) that function in post-transcriptional gene regulation through imperfect base pairing with mRNA targets which results in inhibition of translation and typically destabilization of bound transcripts. Sequence-based algorithms historically used to predict miRNA targets face inherent challenges in reliably reflecting in vivo interactions. Recent strategies have directly profiled miRNA-target interactions by crosslinking and ligation of sncRNAs to their targets within the RNA-induced silencing complex (RISC), followed by high throughput sequencing of the chimeric sncRNA:target RNAs. Despite the strength of these direct profiling approaches, standardized pipelines for effectively analyzing the resulting chimeric sncRNA:target RNA sequencing data are not readily available. Here we present SCRAP, a robust Small Chimeric RNA Analysis Pipeline for the bioinformatic processing of chimeric sncRNA:target RNA sequencing data. SCRAP consists of two parts, each of which are specifically optimized for the distinctive characteristics of chimeric small RNA sequencing reads: first, read processing and alignment and second, peak calling and annotation. We apply SCRAP to benchmark chimeric sncRNA:target RNA sequencing datasets generated by distinct molecular approaches, and compare SCRAP to existing chimeric RNA analysis pipelines. SCRAP has minimal hardware requirements, is cross-platform, and contains extensive annotation to broaden accessibility for processing small chimeric RNA sequencing data and enable insights about the targets of small non-coding RNAs in regulating diverse biological systems.

Mercury Concentrations in Feathers of Albatrosses and Large Petrels at South Georgia: Contemporary Patterns and Comparisons with Past Decades.

Mercury (Hg) is an environmental contaminant that can negatively impact the health of humans and wildlife. Albatrosses and large petrels show some of the highest levels of Hg contamination among birds, with potential repercussions for reproduction and survival. Here, body feather total Hg (THg) concentrations were determined in breeding adults of five species of albatrosses and large petrels in the foraging guild at South Georgia during the mid-2010s. We tested the effects of species, sex and trophic ecology (inferred from stable isotopes) on THg concentrations and compared our results with published values from past decades. Feather THg concentrations differed significantly among species (range: 1.9-49.6 µg g-1 dw), and were highest in wandering albatrosses Diomedea exulans, intermediate in black-browed albatrosses Thalassarche melanophris and northern giant petrels Macronectes halli, and lowest in southern giant petrels M. giganteus and white-chinned petrels Procellaria aequinoctialis. Females were more contaminated than males in all species, potentially due to differences in distributions and diet composition. Across species, THg concentrations were not correlated with feather δ13C or δ15N values, implying that species effects (e.g., breeding and moulting frequencies) may be more important than trophic effects in explaining feather THg concentrations in this foraging guild. Within species, the only significant correlation was between THg and δ13C in wandering albatrosses, which could reflect higher Hg exposure in subtropical waters. Comparisons with THg concentrations from past studies, which reflect contamination from 10 to > 60 years ago, revealed considerable annual variation and some evidence for increases over time for wandering and black-browed albatrosses since before 1950 and from the late 1980s, respectively.

Mercury exposure in an endangered seabird: long-term changes and relationships with trophic ecology and breeding success.

Mercury (Hg) is an environmental contaminant which, at high concentrations, can negatively influence avian physiology and demography. Albatrosses (Diomedeidae) have higher Hg burdens than all other avian families. Here, we measure total Hg (THg) concentrations of body feathers from adult grey-headed albatrosses (Thalassarche chrysostoma) at South Georgia. Specifically, we (i) analyse temporal trends at South Georgia (1989-2013) and make comparisons with other breeding populations; (ii) identify factors driving variation in THg concentrations and (iii) examine relationships with breeding success. Mean ± s.d. feather THg concentrations were 13.0 ± 8.0 µg g-1 dw, which represents a threefold increase over the past 25 years at South Georgia and is the highest recorded in the Thalassarche genus. Foraging habitat, inferred from stable isotope ratios of carbon (δ13C), significantly influenced THg concentrations-feathers moulted in Antarctic waters had far lower THg concentrations than those moulted in subantarctic or subtropical waters. THg concentrations also increased with trophic level (δ15N), reflecting the biomagnification process. There was limited support for the influence of sex, age and previous breeding outcome on feather THg concentrations. However, in males, Hg exposure was correlated with breeding outcome-failed birds had significantly higher feather THg concentrations than successful birds. These results provide key insights into the drivers and consequences of Hg exposure in this globally important albatross population.

An Outbreak Preparedness and Mitigation Approach in Home Health and Personal Home Care During the COVID-19 Pandemic.

The acute respiratory disease COVID-19, caused by the novel Coronavirus SARS-CoV-2, is a worldwide pandemic affecting millions of people. The methodology that organizations who provide home health and personal home care services are using to respond to this pandemic has not yet been characterized. In this report, we describe our approach to comprehensive outbreak suppression and report an initial case series of COVID-19 positive patients receiving home-based services. We implemented enhanced infection control procedures across our affiliates, and we communicated these protocols to our offices using multi-faceted methods. Using custom built software applications enabling us to track patient and employee cases and exposures, we leveraged current public health recommendations to identify cases and to suppress transmission. In the 100-day period between January 20, 2020 and April 30, 2020, our affiliates provided services to 67 COVID-19 positive patients (<0.3% of census). Twenty patients were referred to home health post hospitalization for COVID-19 related illness, whereas 47 were found to have COVID-19 while living in community settings. Of those who were found to have COVID-19 in the community, 17 (39%) required subsequent hospitalization. Hospitalized patients had an average age of 74.5 ± 18, and 53% were male. There were 13 deaths (76%) among those hospitalized from the community with COVID-19 related illness. A highly coordinated and frequently communicated approach to infection control, case identification and employee screening can be performed by home health and personal home care organizations. Studies that further assess risks and predictors of illness severity in home-based COVID-19 patients are needed.

Lactobacillus rescues postnatal neurobehavioral and microglial dysfunction in a model of maternal microbiome dysbiosis.

Increasing reports of pregnancy events leading to maternal microbiome dysbiosis (MMD) show strong correlates with atypical neurodevelopmental outcomes. However, the mechanism(s) driving microbiome-mediated behavioral dysfunction in offspring remain understudied. Here, we demonstrate the presence of a novel gut commensal bacterium strain, Lactobacillus murinus HU-1, was sufficient to rescue behavioral deficits and brain region-specific microglial activationobserved in MMD-reared murine offspring. We furtheridentified a postnatal window of susceptibility that could prevent social impairments with timed maternal administration of the symbiotic bacterium. Moreover, MMD increased expression of microglial senescence genes, Trp53 and Il1ß, and Cx3cr1 protein in the prefrontal cortex, which correlated with dysfunctional modeling of synapses and accompanied dysbiosis-induced microglial activation. MMD male offspring harboring Lactobacillus murinus HU-1 or lacking Cx3cr1 showed amelioration of these effects. The current study describes a new avenue of influence by which maternally transferred Lactobacillus drives proper development of social behavior in the offspring through microglia-specific regulation of Cx3cr1 signaling.

Improving Pediatric Preparedness in Critical Access Hospital Emergency Departments: Impact of a Longitudinal In Situ Simulation Program.

OBJECTIVES: Critical access hospitals (CAH) see few pediatric patients. Many of these hospitals do not have access to physicians with pediatric training. We sought to evaluate the impact of an in situ pediatric simulation program in the CAH emergency department setting on care team performance during resuscitation scenarios. METHODS: Five CAHs conducted 6 high-fidelity pediatric simulations over a 12-month period. Team performance was evaluated using a validated 35-item checklist representing commonly expected resuscitation team interventions. Checklists were scored by assigning zero point for "yes" and 1 point for "no". A lower final score meant more items on the list had been completed. The Kruskal-Wallis rank test was used to assess for differences in average scores among institutions. A linear mixed effects model with a random institution intercept was used to examine trends in average scores over time. P < 0.05 was considered significant. RESULTS: The Kruskal-Wallis rank test showed no difference in average scores among institutions. (P = 0.90). Checklist scores showed a significant downward trend over time, with a scenario-to-scenario decrease of 0.022 (P < 0.01). One hundred percent of providers surveyed in the last month stated they would benefit from ongoing scenarios. CONCLUSIONS: Regularly scheduled pediatric simulations in the CAH emergency department setting improved team performance over time on expected resuscitation tasks. The program was accepted by providers. Implementation of simulation-based training programs can help address concerns regarding pediatric preparedness in the CAH setting. A future project will look at the impact of the program on patient care and safety.

The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin.

Ischemia causes AKI as a result of ATP depletion, and rapid recovery of ATP on reperfusion is important to minimize tissue damage. ATP recovery is often delayed, however, because ischemia destroys the mitochondrial cristae membranes required for mitochondrial ATP synthesis. The mitochondria-targeted compound SS-31 accelerates ATP recovery after ischemia and reduces AKI, but its mechanism of action remains unclear. Here, we used a polarity-sensitive fluorescent analog of SS-31 to demonstrate that SS-31 binds with high affinity to cardiolipin, an anionic phospholipid expressed on the inner mitochondrial membrane that is required for cristae formation. In addition, the SS-31/cardiolipin complex inhibited cytochrome c peroxidase activity, which catalyzes cardiolipin peroxidation and results in mitochondrial damage during ischemia, by protecting its heme iron. Pretreatment of rats with SS-31 protected cristae membranes during renal ischemia and prevented mitochondrial swelling. Prompt recovery of ATP on reperfusion led to rapid repair of ATP-dependent processes, such as restoration of the actin cytoskeleton and cell polarity. Rapid recovery of ATP also inhibited apoptosis, protected tubular barrier function, and mitigated renal dysfunction. In conclusion, SS-31, which is currently in clinical trials for ischemia-reperfusion injury, protects mitochondrial cristae by interacting with cardiolipin on the inner mitochondrial membrane.

Project CAPE: a high-fidelity, in situ simulation program to increase Critical Access Hospital Emergency Department provider comfort with seriously ill pediatric patients.

OBJECTIVES: Variation exists between the qualities of emergency department (ED) care provided to urban versus rural pediatric patients. We implemented a pediatric simulation program in the Critical Access Hospital (CAH) ED setting and evaluated whether this training would increase provider comfort with seriously ill children. METHODS: Five CAH hospitals conducted 6 scenarios for 12 months. Baseline surveys assessed ED staff exposure to and comfort with children. Surveys were repeated after 6 and 12 months. Respondents' answers were matched longitudinally. Changes in responses over time were analyzed using paired t tests for continuous variables. Changes in frequencies and percentages of categorical variables over time were analyzed using χ test. Scenario participants completed an additional survey at the end of each simulation. RESULTS: The baseline survey was completed by 104 of 150 eligible participants, giving a 71% response rate. Fifty-eight percent completed at least 1 additional survey. On survey 1, mean provider comfort score for procedures was 69 (0-100 point scale). Scores increased 6 points from surveys 1 to 2 and a total of 6.5 points from surveys 1 to 3 (P < 0.05).One hundred fifty postscenario surveys were completed. Of the providers, 83.7% believed that scenario participation increased their comfort with children. One hundred percent of the providers in month 12 felt that they would benefit from additional scenarios. CONCLUSIONS: An in situ pediatric simulation program can be implemented effectively in CAH EDs and results in increased comfort with pediatric patients. Such a program could be used as the core feature of a CAH education program aimed at improving the quality of pediatric emergency services provided at these safety net institutions.

Plastic ingestion and trace element contamination of Manx shearwaters Puffinus puffinus on the Faroe Islands.

Procellariiform seabirds can accumulate high levels of plastic in their gastrointestinal tracts, which can cause physical damage and potentially provides a contamination route for trace elements. We examined plastic ingestion and trace element contamination of fledgling Manx shearwaters Puffinus puffinus that were harvested for human consumption in 2003 and 2018 on Skúvoy, Faroe Islands (North Atlantic Ocean). Overall, 88% of fledglings contained plastic in their gastrointestinal tracts, with a mean (± SD) of 7.2 ± 6.6 items weighing 0.007 ± 0.016 g. Though the incidence was similar, fledglings ingested significantly more plastic in 2018 compared to 2003. Hepatic trace element concentrations were unrelated to plastic ingestion. Hepatic carbon (δ13C) and nitrogen (δ15N) stable isotope values were significantly lower in birds sampled in 2018 versus 2003, potentially reflecting further offshore feeding at lower trophic levels. Future research is needed to understand the extent of plastic ingestion by Faroe Islands seabirds.

Safety and Effectiveness Assessment of Ultraviolet-C Disinfection in Aircraft Cabins.

INTRODUCTION: Aircraft cabins, susceptible to disease transmission, require effective strategies to minimize the spread of airborne diseases. This paper reviews the James Reason Swiss Cheese Theory in mitigating these risks, as implemented by the International Civil Aviation Organization during the COVID-19 pandemic. It also evaluates the use of airborne ultraviolet-C (UV-C) light as an additional protective measure.METHODS: Our approach involved a thorough literature review by experts and a detailed risk-vs.-benefit analysis. The review covered existing research to understand the scientific foundation, while the analysis used established techniques to assess the impact of influenza and COVID-19 in terms of infections, deaths, and economic costs.RESULTS: Integrating UV-C light in aircraft cabins, when applied with appropriate scientific understanding and engineering safeguards, has the potential to reduce in-flight disease transmission. This additional mitigation strategy can work synergistically with existing measures.DISCUSSION: The research and risk-vs.-benefit analysis present strong evidence for the safety and effectiveness of continuous UV-C disinfection in aircraft cabins. It suggests that UV-C light, maintained below exposure limits, can be a valuable addition to existing measures against disease transmission during flights.Belland K, Garcia D, DeJohn C, Allen GR, Mills WD, Glaudel SP. Safety and effectiveness assessment of ultraviolet-C disinfection in aircraft cabins. Aerosp Med Hum Perform. 2024; 95(3):147-157.

A Novel Home-Based Medication Management Program and Its Influence on Hospitalization Rates among Home Health Care Recipients.

Patients do not take their medicine as prescribed 50% of the time, and of medication-related hospital admissions in the United States, 33% to 69% are due to poor medication adherence, at a cost of approximately $100 billion a year. Continue CareRx (CCRx) is a novel home-based medication management program that includes adherence packaging alongside medication reconciliation, review, and education by clinicians. We hypothesized that home health patients receiving the CCRx service may have a lower hospitalization rate than control home health patients. Between May 1, 2021, and March 31, 2023, 113 home health patients whose insurance covered the program were enrolled in CCRx. Home health patients not eligible for the program due to a noncovered pharmacy insurance benefit made up the control group (n = 21,304), which was matched with the CCRx group on age range (45-99 years old) and gender (67% women). Hospitalization rate was calculated in both groups and compared using generalized estimating equations analysis. The control group had a total of 7015 hospitalizations during the study period during 2,128,738 total managed days, whereas the CCRx group had 21 hospitalizations during 23,622 total managed days. These translated into rates of 1203 hospitalizations per 1000 per year for the control group, and 324 hospitalizations per 1000 per year for the CCRx group. The results showed that there was a significant main effect of group in predicting individual annual hospitalization rate (Wald χ2 = 56.415, P < .01). Specifically, being in the control group was associated with a 43.42-fold increase in the likelihood of a higher hospitalization rate (95% Wald CI for odds ratios: 7.24-230.44). Home health recipients enrolled in CCRx experienced a 73.1% lower hospitalization rate than controls. Making the program more widely available to patients receiving home health care may present a significant opportunity to reduce hospitalizations in this group.

Growth-suppressor microRNAs mediate synaptic overgrowth and behavioral deficits in Fragile X mental retardation protein deficiency.

Abnormal neuronal and synapse growth is a core pathology resulting from deficiency of the Fragile X mental retardation protein (FMRP), but molecular links underlying the excessive synthesis of key synaptic proteins remain incompletely defined. We find that basal brain levels of the growth suppressor let-7 microRNA (miRNA) family are selectively lowered in FMRP-deficient mice and activity-dependent let-7 downregulation is abrogated. Primary let-7 miRNA transcripts are not altered in FMRP-deficiency and posttranscriptional misregulation occurs downstream of MAPK pathway induction and elevation of Lin28a, a let-7 biogenesis inhibitor. Neonatal restoration of brain let-7 miRNAs corrects hallmarks of FMRP-deficiency, including dendritic spine overgrowth and social and cognitive behavioral deficits, in adult mice. Blockade of MAPK hyperactivation normalizes let-7 miRNA levels in both brain and peripheral blood plasma from Fmr1 KO mice. These results implicate dysregulated let-7 miRNA biogenesis in the pathogenesis of FMRP-deficiency, and highlight let-7 miRNA-based strategies for future biomarker and therapeutic development.

Deleterious effects of mercury contamination on immunocompetence, liver function and egg volume in an antarctic seabird.

Mercury (Hg) is a globally important pollutant that can negatively impact metabolic, endocrine and immune systems of marine biota. Seabirds are long-lived marine top predators and hence are at risk of bioaccumulating high Hg concentrations from their prey. Here, we measured blood total mercury (THg) concentrations and relationships with physiology and breeding parameters of breeding brown skuas (Stercorarius antarcticus) (n = 49 individuals) at Esperanza/Hope Bay, Antarctic Peninsula. Mean blood THg concentrations were similar in males and females despite the differences in body size and breeding roles, but differed between study years. Immune markers (hematocrit, Immunoglobulin Y [IgY] and albumin) were negatively correlated with blood THg concentrations, which likely indicates a disruptive effect of Hg on immunity. Alanine aminotransferase (GPT) activity, reflecting liver dysfunction, was positively associated with blood THg. Additionally, triacylglycerol and albumin differed between our study years, but did not correlate with Hg levels, and so were more likely to reflect changes in diet and nutritional status rather than Hg contamination. Egg volume correlated negatively with blood THg concentrations. Our study provides new insights into the sublethal effects of Hg contamination on immunity, liver function and breeding parameters in seabirds. In this Antarctic species, exposure to sublethal Hg concentrations reflects the short-term risks which could make individuals more susceptible to environmental stressors, including ongoing climatic changes.

A quantitative analysis of Final Palaeolithic/earliest Mesolithic cultural taxonomy and evolution in Europe.

Archaeological systematics, together with spatial and chronological information, are commonly used to infer cultural evolutionary dynamics in the past. For the study of the Palaeolithic, and particularly the European Final Palaeolithic and earliest Mesolithic, proposed changes in material culture are often interpreted as reflecting historical processes, migration, or cultural adaptation to climate change and resource availability. Yet, cultural taxonomic practice is known to be variable across research history and academic traditions, and few large-scale replicable analyses across such traditions have been undertaken. Drawing on recent developments in computational archaeology, we here present a data-driven assessment of the existing Final Palaeolithic/earliest Mesolithic cultural taxonomy in Europe. Our dataset consists of a large expert-sourced compendium of key sites, lithic toolkit composition, blade and bladelet production technology, as well as lithic armatures. The dataset comprises 16 regions and 86 individually named archaeological taxa ('cultures'), covering the period between ca. 15,000 and 11,000 years ago (cal BP). Using these data, we use geometric morphometric and multivariate statistical techniques to explore to what extent the dynamics observed in different lithic data domains (toolkits, technologies, armature shapes) correspond to each other and to the culture-historical relations of taxonomic units implied by traditional naming practice. Our analyses support the widespread conception that some dimensions of material culture became more diverse towards the end of the Pleistocene and the very beginning of the Holocene. At the same time, cultural taxonomic unit coherence and efficacy appear variable, leading us to explore potential biases introduced by regional research traditions, inter-analyst variation, and the role of disjunct macroevolutionary processes. In discussing the implications of these findings for narratives of cultural change and diversification across the Pleistocene-Holocene transition, we emphasize the increasing need for cooperative research and systematic archaeological analyses that reach across research traditions.

A pan-European dataset revealing variability in lithic technology, toolkits, and artefact shapes ~15-11 kya.

Comparative macro-archaeological investigations of the human deep past rely on the availability of unified, quality-checked datasets integrating different layers of observation. Information on the durable and ubiquitous record of Paleolithic stone artefacts and technological choices are especially pertinent to this endeavour. We here present a large expert-sourced collaborative dataset for the study of stone tool technology and artefact shape evolution across Europe between ~15.000 and 11.000 years before present. The dataset contains a compendium of key sites from the study period, and data on lithic technology and toolkit composition at the level of the cultural taxa represented by those sites. The dataset further encompasses 2D shapes of selected lithic artefact groups (armatures, endscrapers, and borers/perforators) shared between cultural taxa. These data offer novel possibilities to explore between-regional patterns of material culture change to reveal scale-dependent processes of long-term technological evolution in mobile hunter-gatherer societies at the end of the Pleistocene. Our dataset facilitates state-of-the-art quantitative analyses and showcases the benefits of collaborative data collation and synthesis.

Projecting water withdrawal and supply for future decades in the U.S. under climate change scenarios.

The sustainability of water resources in future decades is likely to be affected by increases in water demand due to population growth, increases in power generation, and climate change. This study presents water withdrawal projections in the United States (U.S.) in 2050 as a result of projected population increases and power generation at the county level as well as the availability of local renewable water supplies. The growth scenario assumes the per capita water use rate for municipal withdrawals to remain at 2005 levels and the water use rates for new thermoelectric plants at levels in modern closed-loop cooling systems. In projecting renewable water supply in future years, median projected monthly precipitation and temperature by sixteen climate models were used to derive available precipitation in 2050 (averaged over 2040-2059). Withdrawals and available precipitation were compared to identify regions that use a large fraction of their renewable local water supply. A water supply sustainability risk index that takes into account additional attributes such as susceptibility to drought, growth in water withdrawal, increased need for storage, and groundwater use was developed to evaluate areas at greater risk. Based on the ranking by the index, high risk areas can be assessed in more mechanistic detail in future work.

Engineering case report. Toluene and methyl ethyl ketone exposure from a commercially available contact adhesive.

A maintenance worker became ill after working indoors over the course of 3 days with a commercially available contact adhesive containing toluene and methyl ethyl ketone. Respiratory protection or local exhaust ventilation was not used. The worker subsequently suffered from numerous medical symptoms including tremors and elevated blood pressure. Magnetic resonance imaging documented the occurrence of encephalopathy. The worker has alleged that the cause of these effects was exposure to the vapors from the contact adhesive. The objective of this study was to characterize/estimate the level of the worker's exposure by obtaining air samples in an exposure chamber while performing similar activities under similar conditions. We found that the worker may have been exposed to approximately 159 ppm toluene and 58 ppm methyl ethyl ketone 8-hr time-weighted averages for 8 hr of adhesive application. The maximum 15-min average exposures were 233 ppm toluene and 85 ppm methyl ethyl ketone.

Provision of Home-Based Primary Care to Individuals With Intellectual and/or Developmental Disability Is Associated With a Lower Hospitalization Rate Than a Traditional Primary Care Model.

OBJECTIVES: The objective of this study was to determine if providing home-based primary care (HBPC) to individuals with intellectual and/or developmental disabilities (IDD) was associated with a lower hospitalization rate than a control group receiving traditional primary care. DESIGN AND INTERVENTION: Individuals with IDD living in supported residential settings in Ohio were offered HBPC. Individuals electing HBPC made up the intervention group. Those who did not opt for HBPC continued to receive traditional primary care services and made up the control group. Hospitalizations were tracked in both groups. SETTING AND PARTICIPANTS: The 757 study participants had IDD diagnoses and received residential support services throughout the study period. METHODS: Annualized hospitalization rate was determined in both groups and was compared using generalized estimating equations while controlling for patients' age and hospitalization rate in the year prior to the study. RESULTS: The results showed that group membership had a significant effect on the hospitalization rate (Wald χ2 = 20.71, P < .01). Being in the control group was associated with a 2.12-fold increase in annual hospitalization rate for a given patient. The overall population hospitalization rate was 329 hospitalizations per 1000 per year in the HBPC-receiving individuals and 619 hospitalizations per 1000 per year in the control group. CONCLUSIONS AND IMPLICATIONS: We found that individuals with IDD receiving HBPC were hospitalized at a lower rate than a control group receiving traditional primary care. Expanding access to HBPC may be a worthwhile priority for organizations that support individuals with IDD.

Spatial and sex differences in mercury contamination of skuas in the Southern Ocean.

Antarctic marine ecosystems are often considered to be pristine environments, yet wildlife in the polar regions may still be exposed to high levels of environmental contaminants. Here, we measured total mercury (THg) concentrations in blood samples from adult brown skuas Stercorarius antarcticus lonnbergi (n = 82) from three breeding colonies south of the Antarctic Polar Front in the Southern Ocean (southwest Atlantic region): (i) Bahía Esperanza/Hope Bay, Antarctic Peninsula; (ii) Signy Island, South Orkney Islands; and, (iii) Bird Island, South Georgia. Blood THg concentrations increased from the Antarctic Peninsula towards the Antarctic Polar Front, such that Hg contamination was lowest at Bahía Esperanza/Hope Bay (mean ± SD, 0.95 ± 0.45 µg g-1 dw), intermediate at Signy Island (3.42 ± 2.29 µg g-1 dw) and highest at Bird Island (4.47 ± 1.10 µg g-1 dw). Blood THg concentrations also showed a weak positive correlation with δ15N values, likely reflecting the biomagnification process. Males had higher Hg burdens than females, which may reflect deposition of Hg into eggs by females or potentially differences in their trophic ecology. These data provide important insights into intraspecific variation in contamination and the geographic transfer of Hg to seabirds in the Southern Ocean.