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Green turtles Chelonia mydas have been subject to high levels of anthropogenic exploitation, with harvesting at their nesting sites especially pronounced throughout the late 19th and early 20th centuries, leading to worldwide declines. Due to their delayed sexual maturity, long-term protection and monitoring is crucial to allow and accurately demonstrate population recovery. Subsequent to their exploitation, Aldabra Atoll (Republic of Seychelles) has offered the longest continuous protection for nesting green turtles anywhere in the Western Indian Ocean, beginning in 1968. Here, we document the continuing recovery of that population by estimating clutch production within 12 mo nesting seasons over 50 yr of monitoring. An estimated mean of 15297 clutches were laid annually between December 2014 and November 2019. This represents an increase of 173% since Aldabra’s intensive monitoring programme was initiated in 1980, and 410-�665% since 1968. Clutch number increases were recorded at all but 1 of 6 monitored beach groups around the atoll but were most pronounced at Settlement Beach, where exploitation of nesting females was historically most intense. Seasonality data since 2000 showed a year-round nesting season, with elevated activity in April-June peaking on average in May, and a potential shift to later in the year over time. This study highlights the considerable contribution of Aldabra Atoll to regional green turtle numbers and the benefit of long-term protection and monitoring at what can be considered a global reference site for this species.

Ice fabrics – the distribution of crystal orientations in a polycrystal – are key for understanding and predicting ice flow dynamics. Despite their importance, the characteristics and evolution of fabrics produced outside of the deformation regimes of pure and simple shear flow has largely been neglected, yet they are a common occurrence within ice sheets. Here, we use a recently developed numerical model (SpecCAF) to classify all fabrics produced over a continuous spectrum of incompressible two-dimensional deformation regimes and temperatures. The model has been shown to accurately predict ice fabrics produced in experiments, where the ice has been deformed in either uniaxial compression or simple shear. Here we use the model to reveal fabrics produced in regimes intermediate to pure and simple shear, as well as those that are more rotational than simple shear. We find that intermediate deformation regimes between pure and simple shear result in a smooth transition between a fabric characterised by a girdle and a secondary cluster pattern. Highly rotational deformation regimes are revealed to produce a weak girdle fabric. Furthermore, we provide regime diagrams to help constrain deformation conditions of measured ice fabrics. We also obtain predictions for the strain scales over which fabric evolution takes place at any given temperature. The use of our model in large-scale ice flow models and for interpreting fabrics observed in ice cores and seismic anisotropy provides new tools supporting the community in predicting and interpreting ice flow in a changing climate.

Abstract Background Populus trichocarpa is an important forest tree species for the generation of lignocellulosic ethanol. Understanding the genomic basis of biomass production and chemical composition of wood is fundamental in supporting genetic improvement programs. Considerable variation has been observed in this species for complex traits related to growth, phenology, ecophysiology and wood chemistry. Those traits are influenced by both polygenic control and environmental effects, and their genome architecture and regulation are only partially understood. Genome wide association studies (GWAS) represent an approach to advance that aim using thousands of single nucleotide polymorphisms (SNPs). Genotyping using exome capture methodologies represent an efficient approach to identify specific functional regions of genomes underlying phenotypic variation. Results We identified 813 K SNPs, which were utilized for genotyping 461 P. trichocarpa clones, representing 101 provenances collected from Oregon and Washington, and established in California. A GWAS performed on 20 traits, considering single SNP-marker tests identified a variable number of significant SNPs (p-value

Abstract Background The United Kingdom (UK) is experiencing a general practitioner (GP) workforce retention crisis. Research has focused on investigating why GPs intend to quit, but less is known about the acceptability and effectiveness of policies and strategies to improve GP retention. Using evidence from research and key stakeholder organisations, we generated a set of potential policies and strategies aimed at maximising GP retention and tested their appropriateness for implementation by systematically consulting with GPs. Methods 28 GP Partners and GPs working in national stakeholder organisations from South West England and London were purposively sampled, and asked to take part in a RAND/UCLA Appropriateness Method panel. Panellists were asked to read an evidence briefing summary, and then complete an online survey on two occasions. During each round, participants rated the appropriateness of policies and strategies aimed at improving GP retention using a nine point scale (1 ‘extremely inappropriate’ to 9 ‘extremely appropriate’). Fifty-four potential policies and strategies (equating to 100 statements) were tested, focusing on factors influencing job satisfaction (e.g. well-being, workload, incentives and remuneration, flexible working, human resources systems). Ratings were analysed for panel consensus and categorised based on appropriateness (‘appropriate’, ‘uncertain’, ‘inappropriate’). Results 12/28 GPs approached agreed to take part, 9/28 completed two rounds of the online survey between February and June 2018. Panellists identified 24/54 policy and strategy areas (41/100 statements) as ‘appropriate’. Examples included providing GP practices ‘at risk’ of experiencing GP shortages with a toolkit for managing recruitment and retention, and interventions to facilitate peer support to enhance health and wellbeing, or support portfolio careers. Strategies to limit GP workload, and manage patient demand were also endorsed. Conclusions The panel of experienced GPs identified a number of practical ways to improve GP retention through interventions that might enhance job satisfaction and work-life balance. Future research should evaluate the impact of implementing these recommendations.

Objective This study aimed to develop a risk prediction model identifying general practices at risk of workforce supply–demand imbalance.Design This is a secondary analysis of routine data on general practice workforce, patient experience and registered populations (2012 to 2016), combined with a census of general practitioners’ (GPs’) career intentions (2016).Setting/Participants A hybrid approach was used to develop a model to predict workforce supply–demand imbalance based on practice factors using historical data (2012–2016) on all general practices in England (with over 1000 registered patients n=6398). The model was applied to current data (2016) to explore future risk for practices in South West England (n=368).Primary outcome measure The primary outcome was a practice being in a state of workforce supply–demand imbalance operationally defined as being in the lowest third nationally of access scores according to the General Practice Patient Survey and the highest third nationally according to list size per full-time equivalent GP (weighted to the demographic distribution of registered patients and adjusted for deprivation).Results Based on historical data, the predictive model had fair to good discriminatory ability to predict which practices faced supply–demand imbalance (area under receiver operating characteristic curve=0.755). Predictions using current data suggested that, on average, practices at highest risk of future supply–demand imbalance are currently characterised by having larger patient lists, employing more nurses, serving more deprived and younger populations, and having considerably worse patient experience ratings when compared with other practices. Incorporating findings from a survey of GP’s career intentions made little difference to predictions of future supply–demand risk status when compared with expected future workforce projections based only on routinely available data on GPs’ gender and age.Conclusions It is possible to make reasonable predictions of an individual general practice’s future risk of undersupply of GP workforce with respect to its patient population. However, the predictions are inherently limited by the data available.

Abstract Background Around 17% of people attending UK cardiac rehabilitation programmes have depression. Optimising psychological wellbeing is a rehabilitation goal, but provision of psychological care is limited. We developed and piloted an Enhanced Psychological Care (EPC) intervention embedded within cardiac rehabilitation, aiming to test key areas of uncertainty to inform the design of a definitive randomised controlled trial (RCT) and economic evaluation. Methods An external pilot randomised controlled trial (RCT) randomised eight cardiac rehabilitation teams (clusters) to either usual care of cardiac rehabilitation provision (UC), or EPC in addition to UC. EPC comprised mental health care coordination and patient-led behavioural activation with nurse support. Adults eligible for cardiac rehabilitation following an acute coronary syndrome and identified with new-onset depressive symptoms during an initial nurse assessment were eligible. Measures were performed at baseline and 5- and 8-month follow-ups and compared between EPC and UC. Team and participant recruitment and retention rates, and participant outcomes (clinical events, depression, anxiety, health-related quality of life, patient experiences, and resource use) were assessed. Results Eight out of twenty teams were recruited and randomised. Of 614 patients screened, 55 were eligible and 29 took part (5%, 95% CI 3 to 7% of those screened), with 15 patient participants cluster randomised to EPC and 14 to UC. Nurse records revealed that 8/15 participants received the maximum number of EPC sessions offered; and 4/15 received no sessions. Seven out of fifteen EPC participants were referred to another NHS psychological service compared to none in UC. We followed up 27/29 participants at 5 months and 17/21 at 8 months. The mean difference (EPC minus UC) in depressive symptoms (Beck Depression Inventory) at follow-up (adjusting for baseline score) was 1.7 (95% CI − 3.8 to 7.3; N = 26) at 5 months and 4.4 (95% CI − 1.4 to 10.2; N = 17) at 8 months. Discussion While valued by patients and nurses, organisational and workload constraints are significant barriers to EPC implementation. There remains a need to develop and test new models of psychological care within cardiac rehabilitation. Our study offers important data to inform the design of future trials of similar interventions. Trial registration ISRCTN34701576. Registered on 29 May 2014. Funding details: UK NIHR HTA Programme (project 12/189/09).

Background: UK general practice faces a workforce crisis, with general practitioner (GP) shortages, organisational change, substantial pressures across the whole health-care system and an ageing population with increasingly complex health needs. GPs require lengthy training, so retaining the existing workforce is urgent and important. Objectives: (1) To identify the key policies and strategies that might (i) facilitate the retention of experienced GPs in direct patient care or (ii) support the return of GPs following a career break. (2) To consider the feasibility of potentially implementing those policies and strategies. Design: This was a comprehensive, mixed-methods study. Setting: This study took place in primary care in England. Participants: General practitioners registered in south-west England were surveyed. Interviews were with purposively selected GPs and primary care stakeholders. A RAND/UCLA Appropriateness Method (RAM) panel comprised GP partners and GPs working in national stakeholder organisations. Stakeholder consultations included representatives from regional and national groups. Main outcome measures: Systematic review – factors affecting GPs’ decisions to quit and to take career breaks. Survey – proportion of GPs likely to quit, to take career breaks or to reduce hours spent in patient care within 5 years of being surveyed. Interviews – themes relating to GPs’ decision-making. RAM – a set of policies and strategies to support retention, assessed as ‘appropriate’ and ‘feasible’. Predictive risk modelling – predictive model to identify practices in south-west England at risk of workforce undersupply within 5 years. Stakeholder consultation – comments and key actions regarding implementing emergent policies and strategies from the research. Results: Past research identified four job-related ‘push’ factors associated with leaving general practice: (1) workload, (2) job dissatisfaction, (3) work-related stress and (4) work–life balance. The survey, returned by 2248 out of 3370 GPs (67%) in the south-west of England, identified a high likelihood of quitting (37%), taking a career break (36%) or reducing hours (57%) within 5 years. Interviews highlighted three drivers of leaving general practice: (1) professional identity and value of the GP role, (2) fear and risk associated with service delivery and (3) career choices. The RAM panel deemed 24 out of 54 retention policies and strategies to be ‘appropriate’, with most also considered ‘feasible’, including identification of and targeted support for practices ‘at risk’ of workforce undersupply and the provision of formal career options for GPs wishing to undertake portfolio roles. Practices at highest risk of workforce undersupply within 5 years are those that have larger patient list sizes, employ more nurses, serve more deprived and younger populations, or have poor patient experience ratings. Actions for national organisations with an interest in workforce planning were identified. These included collection of data on the current scope of GPs’ portfolio roles, and the need for formal career pathways for key primary care professionals, such as practice managers. Limitations: The survey, qualitative research and modelling were conducted in one UK region. The research took place within a rapidly changing policy environment, providing a challenge in informing emergent policy and practice. Conclusions: This research identifies the basis for current concerns regarding UK GP workforce capacity, drawing on experiences in south-west England. Policies and strategies identified by expert stakeholders after considering these findings are likely to be of relevance in addressing GP retention in the UK. Collaborative, multidisciplinary research partnerships should investigate the effects of rolling out some of the policies and strategies described in this report. Study registration: This study is registered as PROSPERO CRD42016033876 and UKCRN ID number 20700. Funding: The National Institute for Health Research Health Services and Delivery Research programme.

Background: Around 19% of people screened by UK cardiac rehabilitation programmes report having moderate or severe symptoms of depression. These individuals are at an increased risk of cardiac mortality and morbidity, reduced quality of life and increased use of health resources compared with their non-depressed counterparts. Maximising psychological health is a goal of cardiac rehabilitation, but psychological care is patchy. Objective(s): To examine the feasibility and acceptability of embedding enhanced psychological care (EPC) within cardiac rehabilitation, we tested the feasibility of developing/implementing EPC and documented the key uncertainties associated with undertaking a definitive evaluation. Design: A two-stage multimethods study; a feasibility study and a qualitative evaluation, followed by an external pilot cluster randomised controlled trial (RCT) with a nested qualitative study. Setting: UK comprehensive cardiac rehabilitation teams. Participants: Adults eligible for cardiac rehabilitation following an acute coronary syndrome with new-onset depressive symptoms on initial nurse assessment. Patients who had received treatment for depression in the preceding 6 months were excluded. Interventions: The EPC intervention comprised nurse-led mental health-care co-ordination and behavioural activation within cardiac rehabilitation. The comparator was usual cardiac rehabilitation care. Main outcome measures: Measures at baseline, and at the 5- (feasibility and pilot) and 8-month follow-ups (pilot only). Process measures related to cardiac team and patient recruitment, and participant retention. Outcomes included depressive symptoms, cardiac mortality and morbidity, anxiety, health-related quality of life and service resource use. Interviews explored participant and nurses’ views and experiences. Results: Between September 2014 and May 2015, five nurses from four teams recruited participants into the feasibility study. Of the 203 patients screened, 30 were eligible and nine took part (the target was 20 participants). At interview, participants and nurses gave valuable insights into the EPC intervention design and delivery. Although acceptable, the EPC delivery was challenging for nurses (e.g. the ability to allocate sufficient time within existing workloads) and the intervention was modified accordingly. Between December 2014 and February 2015, 8 out of 20 teams approached agreed to participate in the pilot RCT [five were randomised to the EPC arm and three were randomised to the usual-care (UC) arm]. Of the 614 patients screened, 55 were eligible and 29 took part (the target was 43 participants). At baseline, the trial arms were well matched for sex and ethnicity, although the EPC arm participants were younger, from more deprived areas and had higher depression scores than the UC participants. A total of 27 out of 29 participants were followed up at 5 months. Interviews with 18 participants (12 in the EPC arm and six in the UC arm) and seven nurses who delivered EPC identified that both groups acknowledged the importance of receiving psychological support embedded within routine cardiac rehabilitation. For those experiencing/delivering EPC, the intervention was broadly acceptable, albeit challenging to deliver within existing care. Limitations: Both the feasibility and the pilot studies encountered significant challenges in recruiting patients, which limited the power of the pilot study analyses. Conclusions: Cardiac rehabilitation nurses can be trained to deliver EPC. Although valued by both patients and nurses, organisational and workload constraints were significant barriers to implementation in participating teams, suggesting that future research may require a modified approach to intervention delivery within current service arrangements. We obtained important data informing definitive research regarding participant recruitment and retention, and optimal methods of data collection. Future research: Consideration should be given to the delivery of EPC by dedicated mental health practitioners, working closely with cardiac rehabilitation services. Trial registration: Current Controlled Trials ISRCTN34701576. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 30. See the NIHR Journals Library website for further project information.

Studies of annual and geographic variation in eusocial bee populations suggest that more stringent environmental conditions result in stronger reproductive skew favouring queens, while moderate conditions favour increasing worker reproduction. To test these predictions, we compared the phenology and colony development of H. ligatus nesting in St. Catharines, Ontario, Canada to a previously studied aggregation 90 km north of St. Catharines, in Victoria, Ontario. Despite the close proximity of these two locations, St. Catharines has markedly shorter winters and longer summers. Comparisons between St. Catharines in 2006 and Victoria in the 1980s and 1990s incorporate both geographic differences in climate and temporal differences due to climate change. We predicted that St. Catharines foundress queens should emerge from hibernation and initiate nests earlier in spring, giving them time to produce more workers. Since earlier studies indicated that queens have difficulty suppressing worker reproduction in larger colonies, we also predicted higher rates of worker ovarian development in St. Catharines. In spring and summer 2006, we excavated 65 H. ligatus nests, comparing their contents to 713 specimens collected in pan traps. As predicted, nests were initiated about a month earlier in St. Catharines than in Victoria, but contrary to prediction, fewer workers were produced in St. Catharines. St. Catharines workers were just as likely to have developed ovaries as Victoria workers. About 40% of St. Catharines workers were classified as reproductive, and larger reproductive workers tended to have higher ovarian scores. Early queen mortality in the longer nest cycle of St. Catharines bees may have enhanced opportunities for worker reproduction despite their smaller numbers. Novel features of H. ligatus sociobiology in St. Catharines included evidence that queens can initiate new nests following the loss of their first brood, overlap between worker and gyne production within some nests, and high rates of independent nest founding by worker-sized females, suggesting that many worker-brood females overwinter. Overall, the distinctly warmer climate of St. Catharines compared to Victoria led to earlier nest initiation and lengthening of the flight season, but not to the predicted differences in colony social organisation or queen-worker reproductive skew. A second objective of our study was to assess how well pan trap collections capture important information about demographic and social parameters important in assessing social variability in sweat bees. Nest excavations and pan traps produced similar results, suggesting that pan traps are a good alternative when nest excavations are impossible.

Francisella noatunensis subsp. orientalis (Fno) is the causative agent of piscine francisellosis, an emerging infectious disease in Asia and Latin America. In this study two outbreaks of francisellosis were diagnosed in the UK on the basis of histopathology, electron microscopy, PCR, bacterial isolation and fulfillment of Koch's postulates. Furthermore, a phenotypic fingerprint based on biochemical analyses, metabolic activity, chemotaxonomic composition, and antimicrobial assays was generated for the novel isolates, the Fno type strain Ehime-1 from Asia and other Fno from Latin America. The genetic relatedness between the novel Fno and other Francisellaceae species was investigated by sequencing and comparing the 16SrRNA gene, 8 housekeeping genes (individually and concatenated) and the 16SrRNA-ITS-23SrRNA sequence. The phenotypic profiling indicated a high degree of similarity among the Fno strains as all were able to metabolize dextrin, N-acetyl-D glucosamine, D-fructose, α-D-glucose, D-mannose, methyl pyruvate, acetic acid, α-keto butyric acid, L-alaninamide, L-alanine, L-alanylglycine, L-asparagine, L-glutamic acid, L-proline, L-serine, L-threonine, inosine, uridine, glycerol, D L-α-glycerol phosphate, glucose-1-phosphate, and glucose-6-phosphate. The chemotaxonomic analyses indicated that 24:1 (20.3%), 18:1n-9 (16.9%), 24:0 (13.1%) 14:0 (10.9%), 22:0 (7.8%), 16:0 (7.6%), and 18:0 (5.5%) were the predominant structural fatty acids in Fno. The antimicrobial assays showed little variation between the isolates and high susceptibility to enrofloxacin, gentamicin, neomycin, streptomycin, amikacin, ciprofloxacin, gatifloxacin, nitrofurantoin, tobramycin, kanamycin, tetracycline, oxytetracycline, florfenicol, oxolinic acid, and streptomycin in all the Fno analyzed. In all the phylogenetic trees the Fno strains clustered together in independent branches confirming a high degree of homogeneity. Interestingly in five of the 11 trees i.e., mutS, putA, rpoB, 16SrRNA-ITS-23SrRNA, and concatenated sequence the two Francisella noatunensis ssp. diverged more from each other than from the closely related Francisella philomiragia (Fp). The phenotypic and genetic characterization confirmed the Fno isolates represent a solid phylo-phenetic taxon that in the current context of the genus seems to be misplaced within the species Fn. We propose the use of the present polyphasic approach in future studies to characterize strains of Fnn and Fp and verify their current taxonomic rank of Fno and other aquatic Francisella spp.

Tyrosine and phenolic ring de-iodination of thyroid hormones (TH) is crucial for regulating their physiological activity. Furthermore, reactions such as de-carboxylation to thyronamines (TAM) and de-amination to thyroacetic acids (TAc) produce TH metabolites (THM) with distinct biological properties. This needs to be considered when studying effects of TH and THM. The accurate and precise quantitative analysis of TH and THM in cell culture supernatants and cell lysates are key procedures required for studying the in vitro metabolism of TH. We report here the development of a liquid-liquid extraction/isotope dilution-liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) method for the quantification of 9 thyronines (TN) and 6 TAM in human hepatocellular carcinoma Hep G2 cell lysate extracts. In addition, we adapted the method to quantify TH, TAM and TAc, in cell lysates of FBS-depleted rat thyroid epithelium PCCL3 cells. The methods for both cell lines were validated by rigorous assessment of linearity, limits of quantification and detection (LLOQ and LLOD respectively), intra- and inter-day accuracy, precision, process efficiency (PE), matrix effect (ME) and relative recovery (RE). Calibration curves covering 11 concentrations (based on 400 μl of lysate) were linear in the range 0.016-50 nM and 0.010-50 nM for Hep G2 and PCCL3 cells respectively. The lower limits of quantification were in the range 0.031 to 1 nM. We applied the PCCL3 version of the LC-MS/MS method to the analysis of lysed cell extracts from PCCL3 cells that had been incubated with 3-iodo-L-thyronine (T1), 3-iodothyronamine (3-T1AM) and 3-iodothyroacetic acid (3-T1Ac). Over the course of 30 minutes incubation 3-T1AM was de-iodinated to 4-[4-(2-aminoethylphenoxy)]phenol (thyronamine, T0AM) and de-aminated to 3-T1Ac respectively, whilst T1 underwent de-iodination to T0. This data indicates avid metabolism of these mono-iodinated compounds and the utility of LC-MS/MS to quantify such cellular metabolism.

Hepatitis C is a major cause of preventable morbidity and mortality. Prisoners are a key population for hepatitis C control programs, and with the advent of highly effective therapies, prisons are increasingly important sites for hepatitis C diagnosis and treatment. Accurate estimates of hepatitis C prevalence among prisoners are needed in order to plan and resource service provision, however many prevalence estimates are based on surveys compromised by limited and potentially biased participation. We aimed to compare estimates derived from three different data sources, and to assess whether the use of self-report as a supplementary data source may help researchers assess the risk of selection bias. We used three data sources to estimate the prevalence of hepatitis C antibodies in a large cohort of Australian prisoners-prison medical records, self-reported status during a face-to-face interview prior to release from prison, and data from a statewide notifiable conditions surveillance system. Of 1,315 participants, 33.8% had at least one indicator of hepatitis C seropositivity, however less than one third of these (9.5% of the entire cohort) were identified by all three data sources. Among participants of known status, self-report had a sensitivity of 80.1% and a positive predictive value of 97.8%. Any one data source used in isolation would have under-estimated the prevalence of hepatitis C in this cohort. Using multiple data sources in studies of hepatitis C seroprevalence among prisoners may improve case detection and help researchers assess the risk of selection bias due to non-participation in serological testing.

With increasing interest in the use of triploid salmon in commercial aquaculture, gaining an understanding of how economically important pathogens affect triploid stocks is important. To compare the susceptibility of diploid and triploid Atlantic salmon (Salmo salar L.) to viral pathogens, fry were experimentally infected with Salmonid alphavirus sub-type 1 (SAV1), the aetiological agent of pancreas disease (PD) affecting Atlantic salmon aquaculture in Europe. Three groups of fry were exposed to the virus via different routes of infection: intraperitoneal injection (IP), bath immersion, or cohabitation (co-hab) and untreated fry were used as a control group. Mortalities commenced in the co-hab challenged diploid and triploid fish from 11 days post infection (dpi), and the experiment was terminated at 17 dpi. Both diploid and triploid IP challenged groups had similar levels of cumulative mortality at the end of the experimental period (41.1% and 38.9% respectively), and these were significantly higher (p < 0.01) than for the other challenge routes. A TaqMan-based quantitative PCR was used to assess SAV load in the heart, a main target organ of the virus, and also liver, which does not normally display any pathological changes during clinical infections, but exhibited severe degenerative lesions in the present study. The median viral RNA copy number was higher in diploid fish compared to triploid fish in both the heart and the liver of all three challenged groups. However, a significant statistical difference (p < 0.05) was only apparent in the liver of the co-hab groups. Diploid fry also displayed significantly higher levels of pancreatic and myocardial degeneration than triploids. This study showed that both diploid and triploid fry are susceptible to experimental SAV1 infection. The lower virus load seen in the triploids compared to the diploids may possibly be related to differences in cell metabolism between the two groups, however, further investigation is necessary to confirm this and also to assess the outcome of PD outbreaks in other developmental stages of the fish when maintained in commercial production systems.

The importance and consequences of extreme events on the global carbon budget are inadequately understood. This includes the differential impact of extreme events on various ecosystem components, lag effects, recovery times, and compensatory processes. In the summer of 2007 in Barrow, Arctic Alaska, there were unusually high air temperatures (the fifth warmest summer over a 65-year period) and record low precipitation (the lowest over a 65-year period). These abnormal conditions were associated with substantial desiccation of the Sphagnum layer and a reduced net Sphagnum CO2 sink but did not affect net ecosystem exchange (NEE) from this wet-sedge arctic tundra ecosystem. Microbial biomass, NH4+ availability, gross primary production (GPP), and ecosystem respiration (Reco) were generally greater during this extreme summer. The cumulative ecosystem CO2 sink in 2007 was similar to the previous summers, suggesting that vascular plants were able to compensate for Sphagnum CO2 uptake, despite the impact on other functions and structure such as desiccation of the Sphagnum layer. Surprisingly, the lowest ecosystem CO2 sink over a five summer record (2005–2009) was observed during the 2008 summer (~70% lower), directly following the unusually warm and dry summer, rather than during the extreme summer. This sink reduction cannot solely be attributed to the potential damage to mosses, which typically contribute ~40% of the entire ecosystem CO2 sink. Importantly, the return to a substantial cumulative CO2 sink occurred two summers after the extreme event, which suggests a substantial resilience of this tundra ecosystem to at least an isolated extreme event. Overall, these results show a complex response of the CO2 sink and its sub-components to atypically warm and dry conditions. The impact of multiple extreme events requires further investigation.