Urban environment and health: a cross-sectional multiregional project based on population health surveys in Spain (DAS-EP project) - study protocol.

INTRODUCTION: The European Environment Agency estimates that 75% of the European population lives in cities. Despite the many advantages of city life, the risks and challenges to health arising from urbanisation need to be addressed in order to tackle the growing burden of disease and health inequalities in cities. This study, Urban environment and health: a cross-sectional multiregional project based on population health surveys in Spain (DAS-EP project), aims to investigate the complex association between the urban environmental exposures (UrbEEs) and health. METHODS AND ANALYSIS: DAS-EP is a Spanish multiregional cross-sectional project that combines population health surveys (PHS) and geographical information systems (GIS) allowing to collect rich individual-level data from 17 000 adult citizens participating in the PHS conducted in the autonomous regions of the Basque Country, Andalusia, and the Valencian Community, and the city of Barcelona in the years 2021-2023. This study focuses on the population living in cities or metropolitan areas with more than 100 000 inhabitants. UrbEEs are described by objective estimates at participants' home addresses by GIS, and subjective indicators present in PHS. The health outcomes included in the PHS and selected for this study are self-perceived health (general and mental), prevalence of chronic mental disorders, health-related quality of life, consumption of medication for common mental disorders and sleep quality. We aim to further understand the direct and indirect effects between UrbEEs and health, as well as to estimate the impact at the population level, taking respondents' sociodemographic and socioeconomic characteristics, and lifestyle into consideration. ETHICS AND DISSEMINATION: The study was approved by the regional Research Ethics Committee of the Basque Country (Ethics Committee for Research Involving Medicinal Products in the Basque Country; PI2022138), Andalusia (Biomedical Research Ethics Committee of the Province of Granada; 2078-N-22), Barcelona (CEIC-PSMar; 2022/10667) and the Valencian Community (Ethics Committee for Clinical Research of the Directorate General of Public Health and Center for Advanced Research in Public Health; 20221125/04). The results will be communicated to the general population, health professionals, and institutions through conferences, reports and scientific articles.

Sociodemographic, lifestyle, and environmental determinants of vitamin D levels in pregnant women in Spain.

INTRODUCTION: Vitamin D deficiency (<20 ng/mL circulating levels) is a worldwide public health concern and pregnant women are especially vulnerable, affecting the health of the mother and the fetus. This study aims to evaluate the sociodemographic, lifestyle, and environmental determinants associated with circulating vitamin D levels in Spanish pregnant women. METHODS: We used data from the Spanish INMA ("Infancia y Medio Ambiente") prospective birth cohort study from the regions of Gipuzkoa, Sabadell, and Valencia. 25-hydroxyvitamin D3 (25(OH)D3) was measured in plasma collected in the first trimester of pregnancy. Information on 108 determinants was gathered: 13 sociodemographic, 48 lifestyle including diet, smoking and physical activity, and 47 environmental variables, representing the urban and the chemical exposome. Association of the determinants with maternal 25(OH)D3 levels was estimated in single- and multiple-exposure models. Machine learning techniques were used to predict 25(OH)D3 levels below sufficiency (30 ng/mL). RESULTS: The prevalence of < 30 ng/mL 25(OH)D3 levels was 51 %. In the single-exposure analysis, older age, higher socioeconomic status, taking vitamin D, B12 and other sup*plementation, and higher humidity, atmospheric pressure and UV rays were associated with higher levels of 25(OH)D3 (IQR increase of age: 1.2 [95 % CI: 0.6, 1.8] ng/mL 25(OH)D3). In the multiple-exposures model, most of these associations remained and others were revealed. Higher body mass index, PM2.5 and high deprivation area were associated with lower 25(OH)D3 levels (i.e., Quartile 4 of PM2.5 vs Q1: -3.6 [95 % CI: -5.6, -1.5] ng/mL of 25(OH)D3). History of allergy and asthma, being multiparous, intake of vegetable fat, vitamin B6, alcohol consumption and molybdenum were associated with higher levels. The machine learning classification model confirmed some of these associations. CONCLUSIONS: This comprehensive study shows that younger age, higher body mass index, higher deprived areas, higher air pollution and lower UV rays and humidity are associated with lower 25(OH)D3 levels.

Residential green and blue spaces and working memory in children aged 6-12 years old. Results from the INMA cohort.

Availability of green and blue spaces in the area of residence has been related to various health outcomes during childhood, including neurodevelopment. Some studies have shown that children living in greener and/or bluer areas score better on cognitive tasks although the evidence is inconsistent. These protective effects are hypothesized to occur in part through reductions in air pollution exposure and odds of attention-deficit/hyperactivity disorder (ADHD). This study analysed the effects of residential green and blue spaces on working memory of children in the Spanish INfancia y Medio Ambiente (INMA) birth cohort and the potential joint mediating role of air pollution and ADHD. The study samples were composed of 1738 six-to eight-year-olds (M = 7.53, SD = 0.68, 49% female) and 1449 ten-to twelve-year-olds (M = 11.18, SD = 0.69, 50% female) living in Asturias, Gipuzkoa, Sabadell or Valencia, Spain. Individual Normalized Difference Vegetation Index (NDVI) values in 100-, 300- and 500-m buffers and availability of green and blue spaces >5000 m2 in 300-m buffers were calculated using Geographic Information Systems software. Individual NO2 values for the home environment were estimated using ESCAPE's land use regression models. ADHD diagnosis was reported by participants' parents via a questionnaire. Working memory was measured with numbers and colours (in the younger group only) N-back tests (2- and 3-back d'). Mixed-effects models informed of the beneficial effects of NDVI in a 300-m buffer on numerical working memory in the younger sample although the results were not consistent for all d' scores considered and failed to detect significant effects through the candidate mediators. Availability of major blue spaces did not predict working memory performance. Provision of green spaces may play a role in children's working memory but further research is required.

Social inequalities, green and blue spaces and mental health in 6-12 years old children participating in the INMA cohort.

Availability of green and blue spaces in the area of residence has been related to various health outcomes during childhood, including mental health. These environmental exposures are not evenly distributed among socioeconomic groups, which may increase social inequalities in mental health. The mechanisms through which natural environments may promote mental health are numerous and diverse. This study aimed to explore 1) the potential associations of socioeconomic variables (SES and maternal education attainment) with mental health scores and residential greenness, blueness and NO2 metrics, and, 2) the association between greenness and blueness metrics and mental health scores of children in the Spanish INfancia y Medio Ambiente (INMA) birth cohort at two different time points. The study samples were composed of 1738 six-to eight-year-olds (49% female) and 1449 ten-to twelve-year-olds (living in Asturias, Gipuzkoa, Sabadell and Valencia, Spain. Individual Normalized Difference Vegetation Index (NDVI) values in 100-, 300- and 500-m buffers and availability of green and blue spaces >5000 m2 in 300-m buffers were calculated using Geographic Information Systems software. Residential NO2 values were estimated using land use regression models. Internalizing, externalizing and total problems scores were obtained with the Strengths and Difficulties Questionnaire (SDQ). Linear and logistic mixed-effects models revealed unequal distribution of environmental exposures by SES and maternal education but did not show statistically significant associations between greenness and blueness metrics and mental health indicators. The protective effect of green and blue spaces on children's mental health could not be confirmed in this study and therefore further research is required.

Does Time and Size Matter in Retrograde Intrarenal Surgery? Results Analysis Using a Low-Pressure Technique.

PURPOSE: Kidney stone disease affects 5% of the population and is associated with non-negligible morbidity. Retrograde intrarenal surgery and percutaneous nephrolithotomy are the treatments of choice. We analyzed the results from our patients who underwent retrograde intrarenal surgery at controlled pressure. MATERIALS AND METHODS: We conducted an observational, descriptive, retrospective study of 403 patients who underwent retrograde intrarenal surgery at the Hospital Clínico Universitario Lozano Blesa (Zaragoza, Spain) between January 2013 and December 2019. RESULTS: The mean surgical time was 111.1 minutes, with a mean stone volume of 3.5 cm3 (maximum volume, 38.3 cm3). A total of 70 patients (17.3%) developed postoperative Clavien-Dindo complications-64 minor (91.4%) and 6 major (8.6%). In addition, 28 patients (6.9%) presented with an early complication (<3 months), with urinary tract infection and pyelonephritis being the most common. The stone-free rate was 69.0%, with a retreatment rate of 4.7%. CONCLUSIONS: Sex was statistically significantly related to the onset of minor Clavien postoperative complications (p = 0.001). Similarly, corticosteroid use was associated with the onset of major Clavien complications (p = 0.030). Neither surgical time nor stone volume was found to be statistically significantly related to the onset of Clavien postoperative complications or early complications.

Does Time and Size Matter in Retrograde Intrarenal Surgery? Results Analysis Using a Low-Pressure Technique

Purpose: Kidney stone disease affects 5% of the population and is associated with non-negligible morbidity. Retrograde intrarenal surgery and percutaneous nephrolithotomy are the treatments of choice. We analyzed the results from our patients who underwent retrograde intrarenal surgery at controlled pressure. Materials and Methods: We conducted an observational, descriptive, retrospective study of 403 patients who underwent retrograde intrarenal surgery at the Hospital Clínico Universitario Lozano Blesa (Zaragoza, Spain) between January 2013 and December 2019. Results: The mean surgical time was 111.1 minutes, with a mean stone volume of 3.5 cm3 (maximum volume, 38.3 cm3). A total of 70 patients (17.3%) developed postoperative Clavien-Dindo complications—64 minor (91.4%) and 6 major (8.6%). In addition, 28 patients (6.9%) presented with an early complication (<3 months), with urinary tract infection and pyelonephritis being the most common. The stone-free rate was 69.0%, with a retreatment rate of 4.7%. Conclusions: Sex was statistically significantly related to the onset of minor Clavien postoperative complications (p = 0.001). Similarly, corticosteroid use was associated with the onset of major Clavien complications (p = 0.030). Neither surgical time nor stone volume was found to be statistically significantly related to the onset of Clavien postoperative complications or early complications (AU)

Environmental Noise Exposure and Sleep Habits among Children in a Cohort from Northern Spain.

Environmental noise is considered the second most serious environmental risk factor in Europe. However, little evidence exists regarding its impact on health and sleep in children, and the results are inconclusive. In this study, we aim to analyse the effect of environmental noise exposure on 11-year-old children's sleep habits. Data were collected from 377 participants in the INMA-Gipuzkoa (INfancia y Medio Ambiente) cohort project using both parent-reported and actigraphic sleep measures. The results revealed that 60% of children have a day-evening-night environmental noise exposure (Lden) of above 55 dB, which is defined as a "high noise level". No differences in noise exposure were observed between different socioeconomic groups. However, no effect of environmental noise was found on sleep variables. The paper highlights the importance of studying how environmental noise may affect children's sleep.

Achieving high immunogenicity against poliovirus with fractional doses of inactivated poliovirus vaccine in Ecuador-results from a cross-sectional serological survey.

Background: In January 2018, Ecuador changed its routine immunization schedule by replacing one full dose of inactivated poliovirus vaccine (IPV) administered intramuscularly at 2 months of age with two doses of fractional IPV (1/5th of full dose, fIPV) administered intradermally at 2 and 4 months of age; and bivalent oral poliovirus vaccine (serotypes 1 and 3, bOPV) continues to be used. We compared seroprevalence and titres of polio antibodies achieved by the past and the current immunization schedules. Methods: This was a cross-sectional serological survey in children in Ecuador who received bOPV and either one IPV dose in 2017 or two fIPV doses in 2018. One blood sample was collected between October 2020 and March 2021 and analysed for presence of poliovirus neutralizing antibodies at CDC, Atlanta by microneutralization assay. Findings: We obtained 321 analysable samples from 329 (97·6%) enrolled children (160 received IPV and 161 fIPV). For serotype 2, seroprevalence was 50·0% (CI95%= 44·2-55·8%) for IPV and 83·2% (CI95%=78·5-87·1%) for fIPV recipients (p<0·001). Median antibody titers for serotype 2 were significantly lower for IPV than for fIPV recipients (3·0, CI95%= 3 - 3·5 vs. 4·8, CI95%= 4·5 - 5·2, p<0·001). Seroprevalence for serotypes 1 and 3 was above 90% and was not significantly different between IPV and fIPV recipients. Interpretation: Ecuador achieved significantly better poliovirus serotype 2 immunogenicity with two fIPV doses than with one IPV dose, while preserving vaccine supply and reducing costs. Our data provide further evidence that fIPV is a beneficial and potentially a cost-effective option in polio immunization. Funding: WHO obtained funds for the study from Rotary International.

Do prepubertal hormones, 2D:4D index and psychosocial context jointly explain 11-year-old preadolescents' involvement in bullying?

BACKGROUND: Bullying is a type of aggressive behavior that occurs repeatedly and intentionally in school environments and where there is a power imbalance. The main objective of this study was to analyze the association that hormones and the psychosocial context jointly have with bullying behavior. METHOD: Participants were 302 11-year-old preadolescents from the Gipuzkoan cohort of the INMA Project. Bullying was assessed using the Olweus Bully/victim Questionnaire. Prenatal sexual hormones were assessed by calculating 2D:4D ratio and in order to measure prepubertal testosterone and cortisol levels saliva samples were collected within a week of each other. Additionally, various psychosocial factors were evaluated: executive function, family context, school environment and social context. To analyze our complex hypothesis, six metamodels were tested using structural equation modeling. RESULTS: In relation to victims, results showed that victimization was related to worse school environment' perception in boys, and higher stress and conflict in the family in girls. In the case of their involvement in bullying as a bully, lower salivary cortisol levels, worse school environment' perception and lower peers and social support was related to being more frequently involved as a bully in boys, while having more family stress and conflict was related with being a bully in girls. CONCLUSIONS: This approach makes it possible not only to explore the different biological and psychosocial factors affect bullying behavior, but also to explore associations between the predictor variables.

Is Brief Exposure to Green Space in School the Best Option to Improve Attention in Children?

The positive effects of Green Spaces on health are thought to be achieved through the mechanisms of mitigation, instoration and restoration. One of the benefits of Green Spaces may be the restoration of attention and so the objective of this research is testing empirically whether exposure to a green environment improves attention in school children. For so doing, we first used a split-unit statistical design in each of four schools, then combined the primary results via meta-analysis. The Attention Network Test (ANT) was used to measure attention before and after exposure and a total of 167 seven-year-old students participated in the experiments. Overall, our experimental results do not support the hypothesis that students' exposure to activities in green vs. grey spaces affected their performance in ANT. This was so despite the fact that neither age nor gender biases have been detected and despite that our experiments have been proved to be sufficiently statistically powerful. It would be advisable to consider air pollution and noise. We also recommend that participants attend the experiment with mental exhaustion to maximize the ability to detect significant changes.

Does the perceived neighborhood environment promote mental health during pregnancy? Confirmation of a pathway through social cohesion in two Spanish samples.

Physical neighborhood attributes such as greenness, walkability and environmental pollution may have an influence on people's behavior and health. It has been claimed that part of such effects may come from the promotion of physical activity and the strengthening of social cohesion. In this study, we recruited samples of pregnant women in two Spanish cities (Donostia-San Sebastián, 440 participants and Barcelona, 360 participants) who filled in a questionnaire and wore an accelerometer for 1 week during the first trimester of pregnancy. The influence of perceived residential greenness, walkability and environmental pollution on mental health (GHQ-12) was tested in two structural equation models that included light physical activity, moderate-to-vigorous physical activity and social cohesion as mediators. Two solutions showing excellent and good fits (Donostia-San Sebastián: X2(3) = 2.56, p = .465, CFI = 1, RMSEA < 0.001; Barcelona: X2(6) = 4.86, p = .566, CFI = 1, RMSEA = 0.048) consistently showed that neighborhood attributes promote mental health through social cohesion in the two cities. Stratified analyses revealed that the social cohesion-mental health effect was only statistically significant for low and medium socioeconomic status groups in the Donostia-San Sebastián sample. Pathways through physical activity were not confirmed.

Combined effects of urban pollution and hydrological stress on ecosystem functions of Mediterranean streams.

Urban pollution and hydrological stress are common stressors of stream ecosystems, but their combined effects on ecosystem functioning are still unclear. We measured a set of functional processes and accompanying environmental variables in locations upstream and downstream of urban sewage inputs in 13 streams covering a wide range of water pollution levels and hydrological variability. Sewage inputs seriously impaired stream chemical characteristics and led to complex effects on ecosystem functioning. Biofilm biomass accrual, whole-reach nutrient uptake and metabolism (ecosystem respiration) were generally subsidized, whereas organic matter decomposition and biofilm phosphorus uptake capacity decreased with increasing pollutant concentrations. Hydrological stress affected stream ecosystem functioning but its effect was minor compared to the effects of urban pollution, due to the large inter-site variability of the streams. Changes appeared mainly linked to the concentration of pharmaceutically active compounds, followed by other chemical characteristics and by hydrology. The results point to the need to further improve sewage treatment, especially as climate change will stress riverine organisms and reduce the dilution capacity of the receiving streams.

Testing the Multiple Pathways of Residential Greenness to Pregnancy Outcomes Model in a Sample of Pregnant Women in the Metropolitan Area of Donostia-San Sebastián.

Residential greenness may positively impact diverse human health indicators through the reduction of air pollution, the improvement of psychological health, and the promotion of physical activity. Previous studies indicate a weak but positive association with pregnancy outcomes. Our aim was to test the multiple pathways from residential greenness to pregnancy outcomes model, using residential NO2 concentrations, psychological health, and moderate-to-vigorous physical activity (MVPA) during the first trimester of pregnancy, in a sample of 440 pregnant women residing in Donostia, Spain. Three metrics of residential greenness were calculated around each participant's home address: normalized difference vegetation index (NDVI) within 300 m, and green space (>5000 m2) availability within 300 and 500 m. Residential NO2 concentrations, psychological health, and MVPA were explored as mediators of the associations between these metrics and the following pregnancy outcomes: birth weight (BW), low birth weight (LBW), prematurity, small for gestational age (SGA), and large for gestational age (LGA). Educational attainment, parity, and body mass index (BMI) were treated as covariates. Counterfactual mediation analyses showed very low to null statistical support for an association between any of the greenspace metrics and pregnancy outcomes in the full sample. Green space availability (300 m) was associated with lower BW and showed a marginal protective effect against LGA.

Trait-based functional dietary analysis provides a better insight into the foraging ecology of bats.

The degree of trophic specialization determines the ability of predators to cope with changing foraging conditions, but in predators that prey on hundreds of species it is challenging to assess, especially when prey identity varies among predator individuals and across space and time. Here, we test the hypothesis that a bat species foraging on flying insects like moths will show ample flexibility in trophic niche, and this irrespective of phylogenetic relationships among moths, so as to cope with a high diversity of prey types that vary across seasons. We predict that individual bats will show functional dietary differences consistent with energetic requirements and hunting skills. We used DNA metabarcoding to determine the diet of 126 Mediterranean horseshoe bats (Rhinolophus euryale) from two different sites during three seasons. Simultaneously, we measured moth availability and characterized the traits of 290 moth taxa. Next, we explored the relationship between phylogeny and traits of all consumed and available moth taxa. Finally, we assessed the relationship between individual traits of bats and traits related to prey profitability, for which we used the RLQ and fourth-corner statistical techniques. Seasonality was the main factor explaining the functional dietary variation in adult bats, with moths consumed irrespective of their phylogenetic relationships. While adults consumed moths with a broad range in wing loading, body mass and echolocation detection ability, juveniles consumed slower, smaller and lighter moths, which suggests that young individuals may undergo some fitness gain and/or psychomotor learning process during which they would acquire more effective foraging skills. Our approach revealed a degree of functional flexibility in the trophic niche previously unknown for an insectivorous bat. Rhinolophus euryale consumed a wide variety of moth taxa differing in profitability throughout seasons and between ontogenetic stages. We showed the validity of trait-based approaches to gain new insights in the trophic specialization of predators consuming hundreds of species of prey.

Testing wastewater treatment plant effluent effects on microbial and detritivore performance: A combined field and laboratory experiment.

The amount of pollutants and nutrients entering rivers via point sources is increasing along with human population and activity. Although wastewater treatment plants (WWTPs) greatly reduce pollutant loads into the environment, excess nutrient loading is a problem in many streams. Using a Community and Ecosystem Function (CEF) approach, we quantified the effects of WWTP effluent on the performance of microbes and detritivores associated to organic matter decomposition, a key ecosystem process. We measured organic matter breakdown rates, respiration rates and exo-enzymatic activities of aquatic microbes. We also measured food consumption and growth rates and RNA to body-mass ratios (RNA:BM) of a dominant amphipod Echinogammarus berilloni. We predicted responses to follow a subsidy-stress pattern and differences between treatments to increase over time. To examine temporal effects of effluent, we performed a laboratory microcosm experiment under a range of effluent concentrations (0, 20, 40, 60, 80 and 100%), taking samples over time (days 8, 15 and 30; 4 and 10 replicates to assess microbe and detritivore performance respectively, per treatment and day). This experiment was combined with a field in situ Before-After Control-Impact Paired (BACIP) experiment whereby we added WWTP effluent poured (10 L s-1 during 20-40 min every 2 h) into a stream and collected microbial and detritivore samples at days 8 and 15 (5 and 15 replicates to assess the microbe and detritivore performance respectively, per period, reach and sampling day). Responses were clearer in the laboratory experiment, where the effluent caused a general subsidy response. Field measures did not show any significant response, probably because of the high dilution of the effluent in stream water (average of 1.6%). None of the measured variables in any of the experiments followed the predicted subsidy-stress response. Microbial breakdown, respiration rates, exo-enzymatic activities and invertebrate RNA:BM increased with effluent concentrations. Differences in microbial respiration and exo-enzymatic activities among effluent treatments increased with incubation time, whereas microbial breakdown rates and RNA:BM were consistent over time. At the end of the laboratory experiment, microbial respiration rates increased 156% and RN:BM 115% at 100% effluent concentration. Detritivore consumption and growth rates increased asymptotically, and both responses increased with by incubation time. Our results indicate that WWTP effluent stimulates microbial activities and alters detritivore performance, and stream water dilution may mitigate these effects.

Climate and Human Pressure Constraints Co-Explain Regional Plant Invasion at Different Spatial Scales.

Alien species invasion represents a global threat to biodiversity and ecosystems. Explaining invasion patterns in terms of environmental constraints will help us to assess invasion risks and plan control strategies. We aim to identify plant invasion patterns in the Basque Country (Spain), and to determine the effects of climate and human pressure on that pattern. We modeled the regional distribution of 89 invasive plant species using two approaches. First, distance-based Moran's eigenvector maps were used to partition variation in the invasive species richness, S, into spatial components at broad and fine scales; redundancy analysis was then used to explain those components on the basis of climate and human pressure descriptors. Second, we used generalized additive mixed modeling to fit species-specific responses to the same descriptors. Climate and human pressure descriptors have different effects on S at different spatial scales. Broad-scale spatially structured temperature and precipitation, and fine-scale spatially structured human population density and percentage of natural and semi-natural areas, explained altogether 38.7% of the total variance. The distribution of 84% of the individually tested species was related to either temperature, precipitation or both, and 68% was related to either population density or natural and semi-natural areas, displaying similar responses. The spatial pattern of the invasive species richness is strongly environmentally forced, mainly by climate factors. Since individual species responses were proved to be both similarly constrained in shape and explained variance by the same environmental factors, we conclude that the pattern of invasive species richness results from individual species' environmental preferences.

Plasticity to salinity and transgenerational effects in the nonnative shrub Baccharis halimifolia: Insights into an estuarine invasion.

PREMISE OF THE STUDY: Abiotic constraints act as selection filters for plant invasion in stressful habitats. Adaptive phenotypic plasticity and transgenerational effects play a major role in colonization of heterogeneous habitats when the scale of environmental variation is smaller than that of gene flow. We investigated how plasticity and parental salinity conditions influence the performance of the invasive dioecious shrub Baccharis halimifolia, which replaces heterogeneous estuarine communities in Europe with monospecific and continuous stands. METHODS: In two greenhouse experiments, we grew plants derived from seeds and cuttings collected through interspersed patches differing in edaphic salinity from an invasive population. We estimated parental environmental salinity from leaf Na(+) content in parental plants, and we measured fitness and ion homeostasis of the offspring grown in contrasting salinity conditions. KEY RESULTS: Baccharis halimifolia tolerates high salinity but experiences drastic biomass reduction at moderate salinity. At moderate salinity, responses to salinity are affected by the parental salinity: flowering initiation in seedlings and male cuttings is positively correlated with parental leaf Na(+) content, and biomass is positively correlated with maternal leaf Na(+) in female cuttings and seedlings. Plant height, leaf production, specific leaf area, and ionic homeostasis at the low part of the gradient are also affected by parental salinity, suggesting enhanced shoot growth as parental salinity increases. CONCLUSIONS: Our results support plasticity to salinity and transgenerational effects as factors with great potential to contribute to the invasive ability of B. halimifolia through estuarine communities of high conservation value.

Can environmental constraints determine random patterns of plant species co-occurrence?

Plant community ecologists use the null model approach to infer assembly processes from observed patterns of species co-occurrence. In about a third of published studies, the null hypothesis of random assembly cannot be rejected. When this occurs, plant ecologists interpret that the observed random pattern is not environmentally constrained - but probably generated by stochastic processes. The null model approach (using the C-score and the discrepancy index) was used to test for random assembly under two simulation algorithms. Logistic regression, distance-based redundancy analysis, and constrained ordination were used to test for environmental determinism (species segregation along environmental gradients or turnover and species aggregation). This article introduces an environmentally determined community of alpine hydrophytes that presents itself as randomly assembled. The pathway through which the random pattern arises in this community is suggested to be as follows: Two simultaneous environmental processes, one leading to species aggregation and the other leading to species segregation, concurrently generate the observed pattern, which results to be neither aggregated nor segregated - but random. A simulation study supports this suggestion. Although apparently simple, the null model approach seems to assume that a single ecological factor prevails or that if several factors decisively influence the community, then they all exert their influence in the same direction, generating either aggregation or segregation. As these assumptions are unlikely to hold in most cases and assembly processes cannot be inferred from random patterns, we would like to propose plant ecologists to investigate specifically the ecological processes responsible for observed random patterns, instead of trying to infer processes from patterns.

Carcinoma epidermoide en prepucio / Epidermoid carcinoma of the prepuce

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