[Impact of a primary care pharmacy unit on the optimization of pharmacological treatment of type 2 diabetic patients]. / Impacto de una unidad de farmacia de atención primaria en la optimización del tratamiento farmacológico de pacientes diabéticos tipo 2.

OBJECTIVE: To evaluate the impact of a pharmaceutical intervention on treatment optimization in patients with type 2 diabetes mellitus. DESIGN: Before-after intervention study. SITE: Health centers of the Primary Care Department of Camp de Tarragona. PARTICIPANTS: Patients aged ≥ 18 years, diagnosed with type 2 diabetes mellitus and under treatment with antidiabetic drugs. INTERVENTIONS: Review of pharmacological treatment for type 2 diabetes mellitus and issuance of proposals for its adequacy. MAIN MEASUREMENTS: Demographic and clinical variables were collected to assess the adequacy of antidiabetic treatment. A consensus meeting was arranged with the patients' primary care physician to evaluate the proposals for improvement. The implementation of the proposals and the variation in postintervention glycemic control were assessed. RESULTS: A total of 907 patients (59% men) were included. A total of 782 proposals for intervention were made in 65.8% of the patients reviewed. Of the proposals, 43.5% corresponded to drug discontinuation, 16% to intensification of dosing and 12.6% to exchange for a therapeutic equivalent. Of the consensual proposals, 54.7% were implemented. HbA1c was reduced by 0.2% after the intervention (7.4 vs 7.2%). CONCLUSIONS: Review of the pharmacological treatment of patients with type 2 diabetes mellitus by a pharmacist or pharmacologist facilitates its optimization.

Evaluation of a pharmacist-led intervention to reduce drug-related problems in patients included in a home healthcare program: study protocol for a pragmatic randomized clinical trial.

BACKGROUND: ATDOM is the Catalan home healthcare program at primary care level. Patients in the home care program are usually frail, elderly people with multiple comorbidities. They are often polymedicated, leading to a high risk of drug-related problems (DRPs). Our hypothesis is that the pharmacist-led individualized review of the pharmacotherapeutic plans of ATDOM patients will be effective in improving the quality of treatments by reducing DRPs in terms of indication, adequacy, effectiveness, and safety. METHODS: Aim: To compare the effectiveness of a standardized pharmaceutical intervention for the review and optimization of pharmacological treatments in ATDOM patients with usual management practice. DESIGN: Pragmatic randomized clinical trial with a comparable control group, with prospective follow-up regarding the intervention on the adequacy of the pharmacological treatment of patients in the ATDOM program. SETTING: Primary care teams in the Camp de Tarragona Primary Care Area, Tarragona, Spain. PARTICIPANTS: Four hundred and thirty-two ATDOM patients will be recruited, those who are over 65 years old and who are currently undergoing pharmacological treatment. MEASURES: Effectiveness of a six-month long intervention in reducing DRPs per patient and polypharmacy. Additionally, in the intervention group we will evaluate the implementation of the proposals for change or improvement made by the responsible physician. ANALYSIS: The outcomes will be analyzed on an intent-to-treat basis and the analysis units will be the individual patients. Logistic regression and linear regression models will be used to evaluate the effects of the intervention on dichotomous and continuous variables versus the control arm. ETHICS: The protocol was approved by the Research Ethics Committee of the Jordi Gol Primary Care Research Institute (IDIAPJGol), Barcelona, (19/141-P). DISCUSSION: If the results of the pharmaceutical intervention are favorable, widespread implementation of the program could be possible. It could be extended to all ATDOM patients or outpatients in general. Interdisciplinary teamwork could be strengthened as a result, which would improve the healthcare continuum. TRIAL REGISTRATION: Retrospectively registered. CLINICALTRIALS: gov Identifier NCT05820945; Registered 21 March, 2023.

Interaction effects of pH and land cover on soil microbial diversity are climate-dependent.

Factors regulating the diversity and composition of soil microbial communities include soil properties, land cover and climate. How these factors interact at large scale remains poorly investigated. Here, we used an extensive dataset including 715 locations from 24 European countries to investigate the interactive effects of climatic region, land cover and pH on soil bacteria and fungi. We found that differences in microbial diversity and community composition between land cover types depended on the climatic region. In Atlantic, Boreal and Continental regions, microbial richness was higher in croplands and grasslands than woodlands while richness in Mediterranean areas did not vary significantly among land cover types. These differences were further related to soil pH, as a driver of bacterial and fungal richness in most climatic regions, but the interaction of pH with land cover depended on the region. Microbial community composition differed the most between croplands and woodlands in all regions, mainly due to differences in pH. In the Mediterranean region, bacterial communities in woodlands and grasslands were the most similar, whereas in other regions, grassland and cropland-associated bacteria showed more similarity. Overall, we showed that key factors interact in shaping soil microbial communities in a climate-dependent way at large scale.

Patterns in soil microbial diversity across Europe.

Factors driving microbial community composition and diversity are well established but the relationship with microbial functioning is poorly understood, especially at large scales. We analysed microbial biodiversity metrics and distribution of potential functional groups along a gradient of increasing land-use perturbation, detecting over 79,000 bacterial and 25,000 fungal OTUs in 715 sites across 24 European countries. We found the lowest bacterial and fungal diversity in less-disturbed environments (woodlands) compared to grasslands and highly-disturbed environments (croplands). Highly-disturbed environments contain significantly more bacterial chemoheterotrophs, harbour a higher proportion of fungal plant pathogens and saprotrophs, and have less beneficial fungal plant symbionts compared to woodlands and extensively-managed grasslands. Spatial patterns of microbial communities and predicted functions are best explained when interactions among the major determinants (vegetation cover, climate, soil properties) are considered. We propose guidelines for environmental policy actions and argue that taxonomical and functional diversity should be considered simultaneously for monitoring purposes.

Increasing the number of stressors reduces soil ecosystem services worldwide.

Increasing the number of environmental stressors could decrease ecosystem functioning in soils. Yet this relationship has never been globally assessed outside laboratory experiments. Here, using two independent global standardized field surveys, and a range of natural and human factors, we test the relationship between the number of environmental stressors exceeding different critical thresholds and the maintenance of multiple ecosystem services across biomes. Our analysis shows that, multiple stressors, from medium levels (>50%), negatively and significantly correlates with impacts on ecosystem services, and that multiple stressors crossing a high-level critical threshold (over 75% of maximum observed levels), reduces soil biodiversity and functioning globally. The number of environmental stressors >75% threshold was consistently seen as an important predictor of multiple ecosystem services, therefore improving prediction of ecosystem functioning. Our findings highlight the need to reduce the dimensionality of the human footprint on ecosystems to conserve biodiversity and function.

Soil microbial biodiversity promotes crop productivity and agro-ecosystem functioning in experimental microcosms.

Soil biota contribute substantially to multiple ecosystem functions that are key for geochemical cycles and plant performance. However, soil biodiversity is currently threatened by land-use intensification, and a mechanistic understanding of how soil biodiversity loss interacts with the myriad of intensification elements (e.g., the application of chemical fertilizers) is still unresolved. Here we experimentally simplified soil biological communities in microcosms to test whether changes in the soil microbiome influenced soil multifunctionality including crop productivity (leek, Allium porrum). Additionally, half of microcosms were fertilized to further explore how different levels of soil biodiversity interact with nutrient additions. Our experimental manipulation achieved a significant reduction of soil alpha-diversity (45.9 % reduction in bacterial richness, 82.9 % reduction in eukaryote richness) and resulted in the complete removal of key taxa (i.e., arbuscular mycorrhizal fungi). Soil community simplification led to an overall decrease in ecosystem multifunctionality; particularly, plant productivity and soil nutrient retention capacity were reduced with reduced levels of soil biodiversity. Ecosystem multifunctionality was positively correlated with soil biodiversity (R = 0.79). Mineral fertilizer application had little effect on multifunctionality compared to soil biodiversity reduction, but it reduced leek nitrogen uptake from decomposing litter by 38.8 %. This suggests that natural processes and organic nitrogen acquisition are impaired by fertilization. Random forest analyses revealed a few members of protists (i.e., Paraflabellula), Actinobacteria (i.e., Micolunatus), and Firmicutes (i.e., Bacillus) as indicators of ecosystem multifunctionality. Our results suggest that preserving the diversity of soil bacterial and eukaryotic communities within agroecosystems is crucial to ensure the provisioning of multiple ecosystem functions, particularly those directly related to essential ecosystem services such as food provision.

Population-Based Analysis of Trends in Incidence and Survival of Human Papilloma Virus-Related Oropharyngeal Cancer in a Low-Burden Region of Southern Europe.

Introduction: Human papilloma virus (HPV)-related oropharyngeal carcinoma (OPC) can be considered a new subtype of cancer with different clinical characteristics and prognosis than that related to tobacco. Its incidence is increasing worldwide. Its epidemiology has been widely studied in areas such as North America and Northern Europe, but less is known in Southern Europe. Methods: We analyzed the epidemiology of OPC using the database from Girona's population-based Cancer Registry, in the North-East of Spain, from 1994 to 2018. To analyze differences between neoplasms related to human papillomavirus or not, we determined the immunohistochemical expression of p16 in cases within four time periods: 1997-1999, 2003-2005, 2009-2011, and 2016-2018. Results: Oropharyngeal cancer incidence increased significantly from 2001 to 2018 with an Annual Percentage of Change (APC) of 4.1. OPC p16-positive cases increased with an APC of 11.1. In the most recent period, 2016-2018, 38.5% of OPC cases were p16-positive. European age-standardized incidence rate was 4.18 cases/100.000 inhabitants-year for OPC cancer and 1.58 for those p16-positive. Five-year observed survival was 66.3% for p16-positive OPC and 37.7% for p16-negative. Conclusions: Although with lower burden than in other regions, p16-positive oropharyngeal cancer is increasing in our area and has a better prognosis than p16-negative OPC.

Differences in the Impact of COVID-19 on Pathology Laboratories and Cancer Diagnosis in Girona.

INTRODUCTION: The recent COVID-19 pandemic has compromised socio-health care, with consequences for the diagnosis and follow-up of other pathologies. The aim of this study was to evaluate the impact of COVID-19 on cancer diagnosis in Girona, Spain. METHODOLOGY: Observational study of samples received in two pathology laboratories during 2019-2020 (tertiary hospital in Girona and county hospital in Figueres). Date, sample type, and location and morphology were available. Samples were recoded to determine malignancy and grouped by location. Comparisons were made by calendar year and period of exposure to COVID-19. RESULTS: 102,360 samples were included: 80,517 from Girona and 21,843 from Figueres. The reduction in activity in the pathology laboratories in 2020 compared to the previous year was 25.4% in Girona and 27.5% in Figueres. The reduction in cancer diagnoses in 2020 compared to 2019 was 6.8% in Girona and 21% in Figueres. In both laboratories, a decrease was observed in the diagnoses of neoplasms of the lip, oral cavity and pharynx, larynx, colon, rectum and anus, kidney and urinary system, melanoma, and central nervous system. A statistically significant higher probability of a sample received in the pathology laboratory displaying malignancy during COVID-19 was found (Girona: OR = 1.28, 95% CI: 1.23-1.34; Figueres: OR = 1.10, 95% CI: 1.01-1.20) with respect to the COVID-19-free period. CONCLUSIONS: The COVID-19 pandemic has resulted in a reduction in cancer diagnoses by pathology departments that varies according to tumor location and type of hospital. Despite this, the optimization of care resources and the recovery effort have partially reduced the impact of the pandemic in certain neoplasms.

[Patient safety incidents reported before and after the start of the COVID-19 pandemic in Primary Care in Tarragona]. / Incidentes de seguridad del paciente notificados antes y después del inicio de la pandemia de COVID-19 en atención primaria en Tarragona.

OBJECTIVE: To analyse and compare the epidemiology of patient safety incidents reported in Primary Health Care, before and after the start of the COVID-19 pandemic. DESIGN AND SETTING: Analytical descriptive study comparing reported incidents from March 1st 2019 to February 28th 2020, and from March 1st 2020 to February 28th 2021, notified through the TPSC Cloud™ platform accessible from the Intranet corporative in 25 Primary Health Care centres from Tarragona district, in Catalonia (Spain). MEASUREMENTS: Data obtained from voluntary notifications, through electronic, standardized and anonymized forms. VARIABLES: Centre, professional, incident type, risk matrix, causal factors and contributing factors, and avoidability. STATISTICAL ANALYSIS: Every notification was included in descriptive analysis, and another one specifically for adverse events, comparing both periods. RESULTS: 2231 incidents were reported. Comparing both periods, during the pandemic a reduction in the number of reported incidents was observed (only represented 20% of the total). However, the percentage of reported notifications from health care professionals and adverse events that required observation were increased. Causal factors related to attendance and diagnosis were incremented whereas the causal factors related to medication were decreased. In addition, an increase in contributing factors related to the professional was observed. Avoidability was high (>95%) in both periods. CONCLUSIONS: During the pandemic, fewer patient safety incidents have been reported, but proportionally more adverse events, most of which are preventable. The professional himself becomes the main contributing factor.

Population-based analysis of the prevalence of BRAF mutation in patients diagnosed with cutaneous melanoma and its significance as a prognostic factor.

The prevalence of BRAF mutation has been reported in between 38% and 48% of melanoma patients, based on mainly Stage III or metastatic melanoma, however, information based on population-based studies is scarce. We performed a population-based retrospective cohort study to determine the prevalence of the BRAF mutation in patients diagnosed with in situ and infiltrating cutaneous malignant melanoma in the province of Girona between 2009 and 2011. Using the database of the Girona Cancer Registry, we performed BRAF mutation analysis based on paraffin-embedded tissue. This data was then correlated with other known clinical and histological prognostic factors for survival. We found 286 incident cases of cutaneous melanoma in the Girona Cancer Registry database. Excluding missing cases, BRAF-mutated patients constituted 38.9% of "in situ" melanoma cases and 53.8% of invasive melanoma cases. Five-year relative survival was not statistically different between BRAF-mutated patients (93.6%; 95% CI: 87.1-100.5) and non-mutated patients (84.3%, 95% CI: 75.3-94.8). Only stage was significant as a prognostic factor for survival based on multivariate analysis. From our population-based study, we conclude that BRAF mutation is not an independent prognostic factor for melanoma survival.

Analysis of Patient Safety Incidents in Primary Care Reported in an Electronic Registry Application.

OBJECTIVES: (1) To describe the epidemiology of patient safety (PS) incidents registered in an electronic notification system in primary care (PC) health centres; (2) to define a risk map; and (3) to identify the critical areas where intervention is needed. DESIGN: Descriptive analytical study of incidents reported from 1 January to 31 December 2018, on the TPSC Cloud™ platform (The Patient Safety Company) accessible from the corporate website (Intranet) of the regional public health service. SETTING: 24 Catalan Institute of Health PC health centres of the Tarragona region (Spain). PARTICIPANTS: Professionals from the PC health centres and a Patient Safety Functional Unit. MEASUREMENTS: Data obtained from records voluntarily submitted to an electronic, standardised and anonymised form. Data recorded: healthcare unit, notifier, type of incident, risk matrix, causal and contributing factors, preventability, level of resolution and improvement actions. RESULTS: A total of 1544 reports were reviewed and 1129 PS incidents were analysed: 25.0% of incidents did not reach the patient; 66.5% reached the patient without causing harm, and 8.5% caused adverse events. Nurses provided half of the reports (48.5%), while doctors reported more adverse events (70.8%; p < 0.01). Of the 96 adverse events, 46.9% only required observation, 34.4% caused temporary damage that required treatment, 13.5% required (or prolonged) hospitalization, and 5.2% caused severe permanent damage and/or a situation close to death. Notably, 99.2% were considered preventable. The main critical areas were: communication (27.8%), clinical-administrative management (25.1%), care delivery (23.5%) and medicines (18.4%); few incidents were related to diagnosis (3.6%). CONCLUSIONS: PS incident notification applications are adequate for reporting incidents and adverse events associated with healthcare. Approximately 75% and 10% of incidents reach the patient and cause some damage, respectively, and most cases are considered preventable. Adequate and strengthened risk management of critical areas is required to improve PS.

Effectiveness of New Tools to Define an Up-to-Date Patient Safety Risk Map: A Primary Care Study Protocol.

BACKGROUND: Reducing incidents related to health care interventions to improve patient safety is a health policy priority. To strengthen a culture of safety, reporting incidents is essential. This study aims to define a patient safety risk map using the description and analysis of incidents within a primary care region with a prior patient safety improvement strategy organisationally developed and promoted. METHODS: The study will be conducted in two phases: (1) a cross-sectional descriptive observational study to describe reported incidents; and (2) a quasi-experimental study to compare reported incidents. The study will take place in the Camp de Tarragona Primary Care Management (Catalan Institute of Health). In Phase 1, all reactive notifications collected within one year (2018) will be analysed; during Phase 2, all proactive notifications of the second and third weeks of June 2019 will be analysed. Adverse events will also be assessed. Phases 1 and 2 will use a digital platform and the proactive tool proSP to notify and analyse incidents related to patient safety. EXPECTED RESULTS: To obtain an up-to-date, primary care patient safety risk map to prioritise strategies that result in safer practices.

Influence of prior comorbidities and chronic medications use on the risk of COVID-19 in adults: a population-based cohort study in Tarragona, Spain.

OBJECTIVE: To investigate possible relationships between pre-existing medical conditions (including common comorbidities and chronic medications) and risk for suffering COVID-19 disease in middle-aged and older adults. DESIGN: Population-based retrospective cohort study. SETTING: Twelve primary care centres (PCCs) in Tarragona (Spain). PARTICIPANTS: 79 083 people (77 676 community-dwelling and 1407 nursing-home residents), who were all individuals aged >50 years affiliated to the 12 participating PCCs. OUTCOMES: Baseline cohort characteristics (age, sex, vaccinations, comorbidities and chronic medications) were established at study start (1st. March 2020) and primary outcome was time to COVID-19 confirmed by PCR among cohort members throughout the epidemic period (from 1st. March 2020 to 23rd. May 2020). Risk for suffering COVID-19 was evaluated by Cox regression, estimating multivariable HRs adjusted for age, sex, comorbidities and medications use. RESULTS: During the study period, 2324 cohort members were PCR-tested, with 1944 negative and 380 positive results, which means an incidence of 480.5 PCR-confirmed COVID-19 cases per 100 000 persons-period. Assessing the total study cohort, only age (HR 1.02; 95% CI 1.01 to 1.03; p=0.002), nursing-home residence (HR 21.83; 95% CI 16.66 to 28.61; p<0.001) and receiving diuretics (HR 1.35; 95% CI 1.04 to 1.76; p=0.026) appeared independently associated with increased risk. Smoking (HR 0.62; 95% CI 0.41 to 0.93; p=0.022), ACE inhibitors (HR 0.68; 95% CI 0.47 to 0.99; p=0.046) and antihistamine (HR 0.47; 95% CI 0.22 to 1.01; p=0.052) were associated with a lower risk. Among community-dwelling individuals, cancer (HR 1.52; 95% CI 1.03 to 2.24; p=0.035), chronic respiratory disease (HR 1.82; 95% CI 1.08 to 3.07; p=0.025) and cardiac disease (HR 1.53; 95% CI 1.06 to 2.19; p=0.021) emerged to be also associated with an increased risk. Receiving ACE inhibitors (HR 0.66; 95% CI 0.44 to 0.99; p=0.046) and influenza vaccination (HR 0.63; 95% CI 0.44 to 0.91; p=0.012) was associated with decreased risk. CONCLUSION: Age, nursing-home residence and multiple comorbidities appear predisposing for COVID-19. Conversely, receiving ACE inhibitors, antihistamine and influenza vaccination could be protective, which should be closely investigated in further studies specifically focused on these concerns.

Use of distinct anti-hypertensive drugs and risk for COVID-19 among hypertensive people: A population-based cohort study in Southern Catalonia, Spain.

The use of some anti-hypertensive drugs in the current COVID-19 pandemic has become controversial. This study investigated possible relationships between anti-hypertensive medications use and COVID-19 infection risk in the ambulatory hypertensive population. This is a population-based retrospective cohort study involving 34 936 hypertensive adults >50 years in Tarragona (Southern Catalonia, Spain) who were retrospectively followed through pandemic period (from 01/03/2020 to 30/04/2020). Two data sets including demographic/clinical characteristics (comorbidities and cardiovascular medications use) and laboratory PCR codes for COVID-19 were linked to construct an anonymized research database. Cox regression was used to calculate multivariable hazard ratios (HRs) and estimate the risk of suffering COVID-19 infection. Across study period, 205 PCR-confirmed COVID-19 cases were observed, which means an overall incidence of 586.8 cases per 100 000 persons-period. In multivariable analyses, only age (HR: 1.03; 95% CI: 1.02-1.05; P < .001) and nursing home residence (HR: 19.60; 95% CI: 13.80-27.84; P < .001) appeared significantly associated with increased risk of COVID-19. Considering anti-hypertensive drugs, receiving diuretics (HR: 1.22; 95% CI: 0.90-1.67; P = .205), calcium channel blockers (HR: 1.29; 95%CI: 0.91-1.82; P = .148), beta-blockers (HR: 0.97; 95% CI: 0.68-1.37; P = .844), and angiotensin-converting enzyme inhibitors (HR: 0.83; 95% CI: 0.61-1.13; P = .238) did not significantly alter the risk of PCR-confirmed COVID-19, whereas receiving angiotensin II receptor blockers was associated with an almost statistically significant reduction risk (HR: 0.67; 95% CI: 0.44-1.01; P = .054). In conclusion, our data support that receiving renin-angiotensin-aldosterone system inhibitors does not predispose for suffering COVID-19 infection in ambulatory hypertensive people. Conversely, receiving angiotensin II receptor blockers could be related with a reduced risk.

Multiple Stressors Determine Community Structure and Estimated Function of River Biofilm Bacteria.

Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress, and pesticide exposure. We used 24 artificial streams on which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e., a simulated low-flow situation) was the most relevant, since it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57 to 89% of all significant interactions), followed by synergisms (11 to 43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities.IMPORTANCE Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g., toxic chemicals, increased water temperatures, and hydrological alterations) cooccurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.

Effects of multiple stressors on river biofilms depend on the time scale.

Global change exposes ecosystems to a myriad of stressors differing in their spatial (i.e. surface of stressed area) and temporal (i.e. exposure time) components. Among freshwater ecosystems, rivers and streams are subject to physical, chemical and biological stressors, which interact with each other and might produce diverging effects depending on exposure time. We conducted a manipulative experiment using 24 artificial streams to examine the individual and combined effects of warming (1.6 °C increase in water temperature), hydrological stress (simulated low-flow situation) and chemical stress caused by pesticide exposure (15.1-156.7 ng L-1) on river biofilms. We examined whether co-occurring stressors could lead to non-additive effects, and if these differed at two different exposure times. Specifically, structural and functional biofilm responses were assessed after 48 hours (short-term effects) and after 30 days (long-term effects) of exposure. Hydrological stress caused strong negative impacts on river biofilms, whereas effects of warming and pesticide exposure were less intense, although increasing on the long term. Most stressor combinations (71%) resulted in non-significant interactions, suggesting overall additive effects, but some non-additive interactions also occurred. Among non-additive interactions, 59% were classified as antagonisms after short-term exposure to the different stressor combinations, rising to 86% at long term. Our results indicate that a 30-day exposure period to multiple stressors increases the frequency of antagonistic interactions compared to a 48-hour exposure to the same conditions. Overall, the impacts of multiple-stressor occurrences appear to be hardly predictable from individual effects, highlighting the need to consider temporal components such as duration when predicting the effects of multiple stressors.

Desiccation events change the microbial response to gradients of wastewater effluent pollution.

While wastewater treatment plant (WWTP) effluents have become increasingly recognized as a stressor for receiving rivers, their effects on river microbial communities remain elusive. Moreover, global change is increasing the frequency and duration of desiccation events in river networks, and we ignore how desiccation might influence the response of microbial communities to WWTP effluents. In this study, we evaluated the interaction between desiccation events and WWTP effluents under different dilution capacities. Specifically, we used artificial streams in a replicated regressional design, exposing first a section of the streams to a 7-day desiccation period and then the full stream to different levels of a realistic WWTP effluent dilution, from 0% to 100% of WWTP effluent proportion of the total stream flow. The microbial community response was assessed by means of high-throughput sequencing of 16S rRNA gene amplicons and quantitative PCR targeting ecologically-relevant microbial groups. Threshold Indicator Taxa Analysis (TITAN) was used, together with model fitting, to determine community thresholds and potential indicator taxa. Results show significant interactions between WWTP effluents and desiccation, particularly when sediment type is considered. Indicator taxa included members of Proteobacteria, Actinobacteria and Cyanobacteria, with abrupt changes in community structure at WWTP effluent proportion of the total flow above 50%, which is related to nutrient levels ranging 4.6-5.2 mg N-NO3-L-1, 0.21-0.32 mg P-PO43-L-1 and 7.09-9.00 mg DOC L-1. Our work indicates that situations where WWTP effluents account for >50% of the total river flow might risk of dramatic microbial community structure changes and should be avoided.

The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems: A latitudinal study across Europe.

Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06-2.78 ng L-1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8-159 pg L-1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.