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Background Study: Several meta‐analysis studies have investigated the effects of mobile learning on learning performance. However, limited attention has been paid to pedagogy in mobile learning, making quantitative evidence of the effects of pedagogical approaches on learning performance in mobile learning scarce. Filling this gap can therefore help stakeholders understand which mobile pedagogical approaches might work or not under which learning conditions, hence achieving better learning experience and performance. Objectives: To address this gap, this study conducted a meta‐analysis and research synthesis of the effects of integrated pedagogical approaches on students' learning performance in mobile learning. Additionally, this study analysed the field of education, level of education, learning setting, sample size, and mobile device as moderating variables of the effect of pedagogical approaches. Methods: The software Comprehensive Meta‐Analysis V.3 was used for this meta‐analysis, where Hedges' g was calculated for the effect sizes. Specifically, 70 quantitative studies (N = 5575 participants) were coded and analysed. Results: The results indicate that pedagogical approaches in mobile learning have a large effect on students' learning performance (g = 0.93, p < 0.001). The most effective pedagogical approach was project‐based learning (huge effect), while collaborative learning, situated learning and game‐based learning had large effects. Finally, cognitive theory of multimedia learning and inquiry‐based learning had medium effects. The results also indicate that the effect is moderated by the field of education, the level of education, the learning setting, the sample size, and the mobile device. Finally, it is found that study quality might influence the overall effect size. Conclusions: The findings of this study can be beneficial to both researchers and practitioners as they highlight and discuss which pedagogical approaches could be more effective in mobile learning under specific conditions. Further research, on the other hand, should focus on covering additional moderators of learning performance like mobile device type and screen size which is one of the limitations of this study. Lay Description: What is already known about this topic: Mobile learning is widely adopted in education.Mobile learning can enhance learning outcomes. What this paper adds: Pedagogical approaches in mobile learning have different effects on students' learning performance.The most effective pedagogical approach in mobile learning is project‐based learning (huge effect).Which pedagogical approaches could be more effective in mobile learning under specific conditions. Implications for practice and/or policy: This study enriches the ongoing debate on how to design effective mobile learning interventions.This study provides substantial evidence about which pedagogical approaches in mobile learning would be more effective under which circumstances. [ABSTRACT FROM AUTHOR]

Gamification has gained an increasing attention from researchers and practitioners in various domains including education as it can increase learners' engagement and motivation. However, little is known about how educational gamification experiences can be influenced by learners' characteristics. Therefore, this study provides a systematic meta-review of empirical studies related to learners' characteristics and educational gamification experiences. The obtained results from the meta-analysis of forty related articles are: (a) learners' psychological and behavioral outcomes were affected by learners' characteristics in educational gamification systems; (b) quantitative methods, using questionnaires, are the most used method to measure the effect of learners' characteristics on their learning outcomes in educational gamification systems, and this needs to be changed to the new potential of using educational big data and learning analytics approaches; (c) personality traits is the most investigated characteristic followed by player types, but there is a need to further investigate other important factors of learners' characteristics, such as working memory capacity and age; and, (d) a set of game design guidelines that should be taken into consideration while designing educational gamification catering individual difference were proposed. [ABSTRACT FROM AUTHOR]

Governments and private sectors are now putting in place the needed resources and infrastructure to harness the power of emerging technologies in education. One of these technologies is Artificial Intelligence (AI) which gained increasing attention due to its potential to enhance learning and teaching experiences, hence achieving better learning outcomes. However, AIED also comes with several concerns that raise continuous questions about its safe and effective adoption. The application of AIED needs to be planned and executed properly. One of the basic requirements for this to happen is that a comprehensive national policy on the use of AIED is put in place to guide its implementation and evaluate its effectiveness. Limited information exists in the literature on how to write an AIED policy. To address this research gap, this study therefore discusses the features, major components and processes that countries are advised to adopt for a comprehensive AIED policy development. Specifically, this study highlights four features for a good AIED policy, namely contextual, consultative, dynamic, and, implementable and measurable. It further proposes seven steps for an AIED policy development, namely (1) pre-drafting consultation, (2) stakeholder survey, (3) writing draft policy, (4) discussion on draft policy, (5) adoption and communication of policy document, (6) policy implementation plan, and (7) policy evaluation. [ABSTRACT FROM AUTHOR]

While several studies have investigated the effects of educational games in education, less attention has been paid specifically to the effects of educational mobile games in education. To address this gap, this study conducted a meta-analysis and research synthesis of 38 studies (N = 3302 participants) to investigate the effects of educational mobile games on students’ learning performance. The analysis included field of education, level of education, learning setting, intervention duration, and mobile device type as moderating variables of the obtained effects. The findings revealed that educational mobile games have a large effect (g = 0.97) on students’ learning performance, with puzzle games having the largest effect (g = 1.32) on students’ learning performance. Additionally, the analysis found that the obtained effect can be moderated by several variables, including field and level of education, learning setting, intervention duration, and mobile device type. The study findings can help various stakeholders (e.g. educators and game designers or developers) in choosing the appropriate educational mobile games by taking into consideration several related confounding factors. [ABSTRACT FROM AUTHOR]

With the rapid evolution of mobile technology, the adoption of mobile learning in education has also increased. Several studies have conducted various systematic literature reviews to discuss mobile learning from different perspectives, such as its advantages and limitations. However, limited attention has been paid to pedagogy in mobile learning. To address this gap, this study conducts a systematic review of 165 empirical studies on mobile learning to investigate the changing landscape of mobile learning pedagogy. The findings reveal that, despite the ubiquity and flexibility of mobile technologies, most mobile learning studies were conducted in formal settings. The findings also reveal that game-based learning and collaborative learning were the most frequently used pedagogical approaches. Furthermore, redefinition is the most frequently used pedagogical functionality of technology in mobile learning, based on the Substitution Augmentation Modification Redefinition (SAMR) model. The findings of this systematic literature review could be beneficial to both researchers and practitioners in highlighting how mobile learning is designed and implemented, and what gaps should be focused on to enhance pedagogical experiences on mobile devices and thus achieve better mobile learning outcomes. [ABSTRACT FROM AUTHOR]

Online and open learning has recently been made prevalent in many regions in order to mitigate educational inequality and to enhance students' learning experiences and outcomes. Previous studies showed that students perform differently in the learning process, where cultural differences matter. However, little is known about how cultural differences affect students' learning behavioral patterns. This study applies a lag sequential analysis approach to understand the behavioral patterns in an online six-week course of 262 students from three cultures, namely Confucian (for Chinese students), Arab (for Tunisian students), and Serbian (for Serbian students). This study then discusses the different learning behavior patterns based on the theoretical framework of Hofstede's National Cultural Dimensions (NCD). The obtained results highlighted that students from each culture behave differently due to several interconnecting factors, such as educational traditions. The results also showed that some of the learning behaviors were not in line with their students' cultures based on NCD, calling for further investigation in this regard. Finally, the results pointed out that culture is a complex dimension, and further investigation is needed to understand the other dimensions that may affect online and open learning behaviors. [ABSTRACT FROM AUTHOR]

Textbooks use images, in addition to text, for delivering knowledge, thereby convey attitudes and values of students including those on gender bias. The gender bias presented in textbook images affects in subtle ways the students' learning outcomes, career choices, and how they perceive science. However, prior research has relied on explicit information presented by textbook images of several subjects to investigate gender representation, overlooking the implicit meaning behind images with a very limited attention to science textbooks. Therefore, this study uses the social semiotic framework to analyse the implicit meaning that images convey related to gender representation in Chinese and Egyptian science textbooks. Specifically, four (two for each country) science textbooks of grade nine were coded and analysed. The findings revealed that gender gap still exists in the images of both Chinese and Egyptian science textbooks. Specifically, females were less represented in the textbook images compared to males, and their role was mostly a caring role. Notably, unlike the Chinese females and the common gender stereotype, Egyptian females were represented in a more active and powerful way compared to males. The findings of this study could help in better designing science textbook images to reduce gender bias. [ABSTRACT FROM AUTHOR]

Open Educational Resources (OER) aim to open up the access to education for everyone, further enhancing learning quality and facilitating knowledge sharing. Since their official adoption in 2012, OER have gained much attention with various studies being conducted to investigate how educators and students perceive these resources. However, less investigation was paid to OER adoption in developing African countries. Therefore, to promote social justice and facilitate OER adoption in these countries, this study investigates the pedagogical beliefs, teaching practices and use of OER in the Republic of Ghana. The mixed method (questionnaire and semi-structured interviews) was adopted to gain an in-depth understanding into the perceptions that Ghanaian educators have based on their experience with OER and how their interpretations or meanings they have derived from their experience affect the use of OER. The reported findings highlighted that while Ghanaian educators have positive pedagogical beliefs about OER and are using them in their teaching practices, several challenges are reported that might hinder OER adoption in Ghana. For instance, educators raised concerns about intellectual property and difficulty of finding OER. Based on these findings, this study provided recommendations for different stakeholders, to facilitate OER adoption in Ghana, and in similar African countries. [ABSTRACT FROM AUTHOR]

The ability of automatically modeling learners' personalities is an important step in building adaptive learning environments. Several studies showed that knowing the personality of each learner can make the learning interaction with the provided learning contents and activities within learning systems more effective. However, the traditional method of modeling personality is using self-reports, such as questionnaire, which is subjective and with several limitations. Therefore, this study presents a new unobtrusive method to model the learners' personalities in an intelligent Moodle (iMoodle) using Learning Analytic (LA) approach with Bayesian network. To evaluate the accuracy of the proposed approach, an experiment was conducted with one hundred thirty-nine learners in a public university. Results showed that recall, precision, F-measure and accuracy values are in acceptance range for three personality dimensions including extraversion, openness, and neuroticism. Moreover, the results showed that the LA approach has a fair agreement with the Big Five Inventory (BFI) in modeling these three personality dimensions. Finally, this study provides several recommendations which can help researchers and practitioners develop effective smart learning environments for both learning and modeling. For example, it is needed to help identify more features of the hardest personality traits, such as agreeableness, using gamification courses. [ABSTRACT FROM AUTHOR]

Although several studies suggested considering gender in online learning, the literature about how male and female students would behave is fragmented. Little attention has been paid to the effect of gender on online learning behavioural patterns. This study aimed at investigating the roles of gender in online learning behaviours by analyzing the gender-related differences of students' online learning behavioural patterns. We used the case study approach with descriptive statistical analysis, lag sequential analysis, and temporal log data analysis to investigate gender-related differences in students' online learning behaviours. The results indicated no significant difference in the counts of occurrence of online single learning behaviours between female and male students. However, differences were observed in online learning behaviour patterns and how the online learning activities were performed over time. Females were more active in learning behaviours associated with achievement reports and peer list viewing. They tended to view their achievement reports before starting the main course learning activities, indicating that female students might be achievement-oriented. The findings provide further insights from a temporal perspective about how gender is associated with online learning. Implications on designing personalized online learning interventions based on considering gender-related differences are also discussed. [ABSTRACT FROM AUTHOR]

The adoption of Open Educational Resources (OER) can, on the one hand, increase access and quality in higher education, but on the other hand it is raising concerns among universities and researchers about its economic sustainability. This is mainly because, unlike traditional online learning, in OER-based approaches learners do not have to pay to access learning resources, however the institution incurs costs for the production, maintenance and dissemination of OER. In this context, the United Nations Educational, Scientific and Cultural Organisation (UNESCO) has urgently called for more research on OER sustainability models in its 2019 OER recommendation. To contribute to a better understanding of this issue, this paper used the triangulation method to investigate the potential OER sustainability models that are currently implemented by universities, along with their challenges and possible developments. Through a comprehensive literature review and a 2-round Delphi method with thirty OER experts, ten OER sustainability models have been identified and analysed, where public and internal funding are the most established ones. The findings of this study could support organisations in developing their own OER sustainability strategy, facilitating OER adoption worldwide and therefore contributing to achieving the UN Sustainable Development Goals (SDGs). [ABSTRACT FROM AUTHOR]

There is an ongoing debate in the literature about the ways of using technology to enhance students' Computational Thinking (CT). This special issue further enriches this debate by investigating how educational technology could be used, and for which purposes, to facilitate learning CT. It includes six papers demonstrating the innovative design of curricula and the use of various technologies to teach CT for students in different educational levels. Based on these papers, this special issue points out that more research is needed to investigate the best educational practices that could be used to teach CT rather than focusing on the technology itself. It also reveals that future work could cover smart learning analytics and precision education to better model students' individual differences, hence effectively supporting learning CT. [ABSTRACT FROM AUTHOR]

The lack of teachers and equipment is a major obstacle to the implementation of Computational Thinking (CT) in education, particularly for rural schools. Although CT education has been investigated for many years, less attention has been paid to lower primary schools in rural areas. This study contributes to filling this gap by investigating the impact of three different learning approaches on the CT of grade-two primary school students in a rural area in China. Seventy-seven students were randomly assigned to three learning approaches, namely traditional lectures, Game-Based Learning (GBL) using a newly designed board game in classrooms, and GBL with parental involvement. The findings showed that both GBL approaches (i.e., with and without parents) significantly enhanced the students' CT skills compared to the traditional approach. The findings also showed that the GBL approach with parental involvement significantly enhanced students' attitudes toward learning CT compared with the other two approaches. [ABSTRACT FROM AUTHOR]

Trichobezoars are foreign and indigestible materials in the gastrointestinal tract and are usually found in psychiatric females, who often deny eating their own hair, but also at situations of gastric dysmotility and prior gastric surgery. Although rare, gastric trichobezoar should not be forgotten as a differential diagnosis in females presenting with vague epigastric pain. Its treatment well in time will prevent complications. [ABSTRACT FROM AUTHOR]

Although several studies have been conducted to summarize the progress of open educational resources (OER) in specific regions, only a limited number of studies summarize OER in Africa. Therefore, this paper presents a systematic literature review to explore trends, themes, and patterns in this emerging area of study, using content and bibliometric analysis. Findings indicated three major strands of OER research in Africa: (1) OER adoption is only limited to specific African countries, calling for more research and collaboration between African countries in this field to ensure educational equity; (2) most of the OER initiatives in Africa have focused on the creation process and neglected other important perspectives, such as dissemination and open educational practices (OEP) using OER; and (3) on top of the typical challenges for OER adoption (e.g., infrastructure), other personal challenges were identified within the African context, including culture, language, and personality. The findings of this study suggest that more initiatives and cross-collaborations with African and non-African countries in the field of OER are needed to facilitate OER adoption in the region. Additionally, it is suggested that researchers and practitioners should consider individual differences, such as language, personality and culture, when promoting and designing OER for different African countries. Finally, the findings can promote social justice by providing insights and future research paths that different stakeholders (e.g., policy makers, educators, practitioners, etc.) should focus on to promote OER in Africa. [ABSTRACT FROM AUTHOR]

Background: Hydatid disease is endemic in Mediterranean countries and most commonly occurs in the liver followed by the lung. A primary localization in the retroperitoneum is extremely rare. Case presentation: We report the case of a 29-year-old Tunisian patient presenting with progressive left flank pain and skin urticaria. On abdominal ultrasonography and computed tomography scan, a ruptured retroperitoneal hydatid cyst was diagnosed, which was confirmed by positive hydatid serology. The treatment consisted of resection of protruding dome. The evolution was favorable. No local recurrence was detected during postoperative follow-up. Conclusions: Primary retroperitoneal hydatid cyst is extremely rare and has uncommon presentation, but we should learn the keys to its diagnosis. In endemic regions, high suspicion for this disease is justified regardless of localization. [ABSTRACT FROM AUTHOR]

Background: Hydatid disease is endemic in Mediterranean countries and most commonly occurs in the liver followed by the lung. A primary localization in the retroperitoneum is extremely rare.Case Presentation: We report the case of a 29-year-old Tunisian patient presenting with progressive left flank pain and skin urticaria. On abdominal ultrasonography and computed tomography scan, a ruptured retroperitoneal hydatid cyst was diagnosed, which was confirmed by positive hydatid serology. The treatment consisted of resection of protruding dome. The evolution was favorable. No local recurrence was detected during postoperative follow-up.Conclusions: Primary retroperitoneal hydatid cyst is extremely rare and has uncommon presentation, but we should learn the keys to its diagnosis. In endemic regions, high suspicion for this disease is justified regardless of localization. [ABSTRACT FROM AUTHOR]

The rapid advancements in online education have pointed to a new open learning approach using Open Educational Resources (OER). In this approach, educators and learners can freely access or redistribute educational resources that have been released online in the public domain under an open licence. Whereas this approach looks appealing in reducing learning costs, as well as in enhancing learning quality and facilitating knowledge sharing, several challenges might hinder the adoption of OER, such as locating and selecting the most appropriate resources among the thousands that are published and that are available online, and trusting them. This paper elaborates on those challenges and suggests an emerging technologies-based perspective for addressing the efficient inclusion of OER. To this end, this paper discusses how the integration of emerging yet essential technologies, such as Artificial Intelligence (AI) and blockchain, with big learning data and educational data mining algorithms could have a profound impact on enhancing OER-based learning and teaching. The dynamics of incorporating these technologies to solve several OER challenges are demonstrated through numerous examples, and the potential limitations are also discussed. The paper concludes with visions of the future, possible research challenges and directions. [ABSTRACT FROM AUTHOR]

The design, implementation, and outcome of educational robots in special education have not been sufficiently examined in a systematic way. In particular, learner-based and contextual factors, as well as the essential roles played by various stakeholders have not been addressed when robots are used as a learning tool in special education. Therefore, a systematic review using Activity Theory was conducted to analyze 30 studies in robot-assisted special education. Content analysis of the studies reported relevant information with respect to each activity component - (a) subject (learners with disabilities), (b) technology (robots supported by instructional design), (c) object (target skills or behaviors), (d) rules (implementation procedure and performance measures), (e) community (learners with disabilities, special education professionals, and parents), (f) division of labor (among learners, professionals and parents), and (g) outcome (performance of target skills or behaviors). Furthermore, the study identified existing gaps from the robot-assisted special education studies (e.g., lack of parental engagement), challenges (e.g., difficulty with standardizing performance measures due to heterogeneity of learner profiles), and contradictions (e.g., opposing views among experts on the role of robots in social interactions). Finally, recommendations were made under each activity component. The study concluded that both general and domain-specific guidelines should be created for each disability category proposed in this review to assist practitioners who wish to use robots to assist special education. [ABSTRACT FROM AUTHOR]

Bleeding during pregnancy may not be due to obstetric causes. Pregnancy is a predisposing factor for some disorders due to physiological changes. These obstetric bleedings are rare but are responsible for high materno-fetal mortality. Prognosis depends on the speed of diagnosis as well as on multidisciplinary management. Splenic artery aneurysm (SAA) rupture during pregnancy is rare with a dreadful prognosis. Commo n clinical signs including abdominal pain associated with hypotension and anemia are very misleading for the obstetrician who usually suspects retroplacental hematoma or uterine rupture. We report the case of a pregnant patient requiring emergency laparotomy due to the detection of splenic artery aneurysm rupture on imaging test. [ABSTRACT FROM AUTHOR]

Learner modeling is a crucial step in the learning personalization process. It allows taking into consideration the learner's profile to make the learning process more efficient. Most studies refer to an explicit method, namely questionnaire, to model learners. Questionnaires are time consuming and may not be motivating for learners. Thus, this paper presents a new approach for Modeling the learner's Personality, introvert/extrovert, using Educational Games (MoPEG). The proposed approach includes three phases, namely design of the educational game, collection of traces and personality prediction. To evaluate the efficiency of MoPEG, an experiment was conducted with thirty learners where their personality modeling results using MoPEG are compared to the Big Five Inventory (BFI) questionnaire. The obtained results showed that the accuracy level of MoPEG is significant with an 80% of similarity. Besides, based on the Kappa method, used by psychologists to measure the similarity of two instruments. The obtained results highlighted an agreement degree of MoPEG with the level "good". [ABSTRACT FROM AUTHOR]

The overarching aim of this field study was to examine causal links between in-situ exposure to complex mixtures of micropollutants from wastewater treatment plants and effects on freshwater microbial communities in the receiving streams. To reach this goal, we assessed the toxicity of serial dilutions of micropollutant mixtures, extracted from deployed passive samplers at the discharge sites of four Swiss wastewater treatment plants, to in situ periphyton from upstream and downstream of the effluents. On the one hand, comparison of the sensitivities of upstream and downstream periphyton to the micropollutant mixtures indicated that algal and bacterial communities composing the periphyton displayed higher tolerance towards these micropollutants downstream than upstream. On the other hand, molecular analyses of the algal and bacterial structure showed a clear separation between upstream and downstream periphyton across the sites. This finding provides an additional line of evidence that micropollutants from the wastewater discharges were directly responsible for the change in the community structure at the sampling sites by eliminating the micropollutant-sensitive species and favouring the tolerant ones. What is more, the fold increase of algal and bacterial tolerance from upstream to downstream locations was variable among sampling sites and was strongly correlated to the intensity of contamination by micropollutants at the respective sites. Overall, our study highlights the sensitivity of the proposed approach to disentangle effects of micropollutant mixtures from other environmental factors occurring in the field and, thus, establishing a causal link between exposure and the observed ecological effects on freshwater microbial communities. [ABSTRACT FROM AUTHOR]

With the accelerated use of silver nanoparticles (AgNP) in commercial products, streams will increasingly serve as recipients of, and repositories for, AgNP. This raises concerns about the potential toxicity of these nanomaterials in the environment. Here we aimed to assess the impacts of chronic AgNP exposure on the metabolic activities and community structure of fungal and bacterial plant litter decomposers as central players in stream ecosystems. Minimal variation in the size and surface charge of AgNP indicated that nanoparticles were rather stable during the experiment. Five days of exposure to 0.05 and 0.5 µM AgNP in microcosms shifted bacterial community structure but had no effect on a suite of microbial metabolic activities, despite silver accumulation in the decomposing leaf litter. After 25 days, however, a broad range of microbial endpoints, as well as rates of litter decomposition, were strongly affected. Declines matched with the total silver concentration in the leaves and were accompanied by changes in fungal and bacterial community structure. These results highlight a distinct sensitivity of litter-associated microbial communities in streams to chronic AgNP exposure, with effects on both microbial functions and community structure resulting in notable ecosystem consequences through impacts on litter decomposition and further biogeochemical processes. [ABSTRACT FROM AUTHOR]

A major challenge in environmental risk assessment of pollutants is establishing a causal relationship between field exposure and community effects that integrates both structural and functional complexity within ecosystems., Pollution-induced community tolerance (PICT) is a concept that evaluates whether pollutants have exerted a selection pressure on natural communities. PICT detects whether a pollutant has eliminated sensitive species from a community and thereby increased its tolerance. PICT has the potential to link assessments of the ecological and chemical status of ecosystems by providing causal analysis for effect-based monitoring of impacted field sites., Using PICT measurements and microbial community endpoints in environmental assessment schemes could give more ecological relevance to the tools that are now used in environmental risk assessment. Here, we propose practical guidance and a list of research issues that should be further considered to apply the PICT concept in the field. [ABSTRACT FROM AUTHOR]

Ecology and ecotoxicology have different historical roots, despite their similar names, but are slowly converging to meet the challenge of addressing the massive global proliferation and release of chemicals in the environment. The conceptual, methodological, review and standard research papers in this special issue reflect this emerging trend of blending ecological and ecotoxicological perspectives to assess impacts in freshwater ecosystems., Assessing community and ecosystem impacts of chemical contaminants is complex, however, and will require approaches that explicitly consider biological and chemical diversity as well as the natural variability of environmental factors at multiple spatial and temporal scales., Central themes of the papers in this issue are (i) the importance of indirect effects of chemical contaminants on species interactions and food webs; (ii) effects of multiple stressors, especially interactions between contaminants and environmental factors; (iii) consequences of chemical exposure on ecosystem processes such as primary production and litter decomposition; (iv) the need to account for context dependency and (v) potentially harmful community and ecosystem effects of emerging contaminants, among which nanoparticles are prominently represented., Collectively, these papers show that integrating ecological principles into the design and implementation of ecotoxicological research is essential for assessing and predicting contaminant impacts on biological communities and ecosystems. Conversely, applied ecology and bioassessment would benefit from concepts and approaches developed in ecotoxicology and from fully embracing chemical contaminants as key drivers of community structure and ecosystem processes. [ABSTRACT FROM AUTHOR]

With the rapid growth of technology enhanced learning, new mediums for learning have emerged. One of these mediums is computer based learning where the main concern is how to design a computer based learning system which takes into consideration the learners' differences. Personality is considered as one of the most critical sources of individual differences. This study investigates how personality differences within learners can affect computer based learning, through a comprehensive review of the literature. The highlighted results from the obtained nineteen studies are: (a) the most referred to personality model in computer based learning is MBTI; (b) personality traits affect how learners prefer learning content and learning approach like collecting information, communicating with instructor and peer, study behavior, acting and performing; (c) a new model of personality variables should be considered in computer based learning by taking all interested researchers and practitioners into accounts; and (d) the traditional questionnaire approach which is still the pre-dominant method to identify the learner's personality; and this needs to be changed with new potential of big data and learning analytics. Furthermore, this study presents a new implicit approach using learning analytics instead of questionnaire-based approach to identify the learner's personality. [ABSTRACT FROM AUTHOR]

The rapid proliferation of silver nanoparticles (AgNP) in industry and the environment requires realistic toxicity assessments based on approaches that consider the biological complexity of ecosystems. Here we assessed the acute toxicity of carbonate-coated AgNP and, for comparison, AgNO3(Ag+) by using a model system consisting of decomposing plant litter and the associated fungal and bacterial decomposers as central players in the functioning of stream ecosystems. Little variation in size and surface charge during the experiment indicated that the AgNP used were essentially stable. AgNP disrupted bacterial growth (≤83% reduction in protein biosynthesis, EC50 = 0.3 μM), clearly affected fungal growth (≤61% reduction in ergosterol synthesis, EC50 = 47 μM) with both endpoints more sensitive to AgNP than to Ag+. Fungal reproduction, in contrast, was stimulated by AgNP, but not Ag+, at concentrations up to 25 μM. Both AgNP and Ag+ also stimulated extracellular alkaline phosphatase but reduced leucine aminopeptidase, whereas β-glucosidase was stimulated by AgNP and reduced by Ag+. Importantly, the provision of cysteine, a chelating ligand that complexes free Ag+, failed to alleviate AgNP toxicity to microbial growth, clearly demonstrating particle-mediated toxicity independent of the presence of ionic silver. This contrasts with the observed inhibition of leucine aminopeptidase by Ag+, which accounted for 2–6% of the total silver in treatments receiving AgNP. These results show that although outcomes of AgNP and Ag+ exposure assessed by different functional endpoints vary widely, AgNP strongly interferes with bacterial growth and a range of other microbial processes, resulting in severe consequences for natural microbial communities and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Highlights: [•] Antioxidant enzymes activities (AEA) are changing throughout biofilm growth. [•] AEA in control and in biofilms exposed to oxyfluorfen have similar ranges of variation. [•] Oxyfluorfen chronic exposure affected structure (diversity) and function (catalase). [•] AEA in acute toxicity tests: a tool to compare previous exposure to oxidative stress. [•] After chronic exposure, catalase responded to higher levels of oxidative stress. [Copyright &y& Elsevier]

Abstract: Understanding the interactive effects of multiple stressors on ecosystems has started to become a major concern. The aim of our study was therefore to evaluate the consequences of a long-term exposure to environmental concentrations of Cu, Zn and As on the pollution-induced community tolerance (PICT) of lotic biofilm communities in artificial indoor channels. Moreover, the specificity of the PICT was assessed by evaluating the positive and negative co-tolerance between these metals. Photosynthetic efficiency and substrate-induced respiration (SIR), targeting the autotrophic and heterotrophic communities respectively were used in short-term inhibition bioassays with Cu, Zn and As to assess sensitivities of pre-exposed biofilms to the metals tested. Diversity profiles of a phototrophic, eukaryotic and prokaryotic community in biofilms following the different treatments were determined and analyzed with principal component analysis. The results demonstrated that pre-exposure to metals induced structural shifts in the community and led to tolerance enhancements in the phototrophic and heterotrophic communities. On the other hand, whatever the functional parameter used (i.e. photosynthesis and SIR), communities exposed to Cu were more tolerant to Zn and vice versa. Furthermore, only phototrophic communities pre-exposed to As developed tolerance to Cu but not to Zn, whereas no co-tolerance between Cu and As was observed in the heterotrophic communities. Finally, phototrophic and heterotrophic communities exposed to Cu and Zn became more sensitive to As, reflecting a negative co-tolerance between these metals. Overall, our findings support the fact that although the mode of action of the different metals is an important driver for the structure and thus the tolerance of the communities, it appears that the detoxification modes are the most important factors for the occurrence of positive or negative co-tolerance. [Copyright &y& Elsevier]

Abstract: Aquatic ecosystems face variable exposure to pesticides, especially during floodings which are associated with short bursts of high contaminant concentrations that influence biological systems. A study was undertaken to highlight the impact of the herbicide diuron applied in mixture with the fungicide tebuconazole on natural periphyton during flooding events. Periphyton were grown in two series of two lotic outdoor mesocosms: one series was non-contaminated while the other was exposed to chronic contamination. After 4weeks, one channel of each series was exposed to three successive pulses, with each pulse followed by one week of recovery. Impacts on periphyton were assessed by using Denaturing Gel Gradient Electrophoresis to characterize eukaryotic community structure. At a functional scale, photosynthetic efficiency was quantified during each pulse, and the induced tolerance to diuron was estimated by performing short-term inhibition tests based on photosynthetic efficiency. Moreover, pesticide concentrations in the water column and periphyton matrix were measured. Diuron was adsorbed in the periphyton during each pulse and desorbed 13h after pulse end. The different pulses affected the eukaryotic community structures of the control biofilms, but not of the chronically exposed ones. During the first pulse, photosynthetic efficiency was correlated with pesticide concentration in the water phase, and there was no difference between periphyton from chronically contaminated channels and control channels. However, during the second and third pulses, the photosynthetic efficiency of periphyton chronically exposed to pesticides appeared to be less impacted by the acute pulsed exposure of pesticide. These changes were consistent with the acquisition of induced tolerance to diuron since only after the third pulse that periphyton from chronic channel became tolerant to diuron. Our experimental study indicates that the effects of pulsed acute exposures to pesticides on periphyton depended on whether the communities had previously been exposed to the same stressors or not. [Copyright &y& Elsevier]

Abstract: Pollution-induced community tolerance (PICT) concept is based on the assumption that the toxicant exerts selection pressure on the biological communities when exposure reaches a critical level for a sufficient period of time and therefore sensitive species are eliminated. However, induced tolerance of microbial biofilm communities cannot be attributed solely to the presence of toxicants in rivers but also to various environmental factors, such as amount of nutrients. An experimental study was undertaken to highlight the potential impact of a phosphorus gradient on the sensitivity of periphytic microbial community to Cu and diuron. Biofilms were exposed to real-world levels of chronic environmental contamination of toxicants with a phosphorus gradient. Biofilm sensitivity to Cu and diuron was assessed by performing short-term inhibition tests based on photosynthetic efficiency to target photoautotrophs, extracellular enzyme activity (β-glucosidase and leucine-aminopeptidase) and substrate-induced respiration activity to target heterotrophs. The impact of P-gradient associated to pollution was evaluated by measuring pesticide concentrations in biofilms, biomass parameters (chla, AFDW), bacterial cell density, photosynthetic efficiency and community structure (using 18S and 16S rDNA gene analysis to target eukaryotes and DGGE and HPLC pigment analysis to target bacteria and photoautotrophs). The obtained results show that depending on the studied toxicant and the used structural or functional parameter, the effect of the phosphorus gradient was variable. This highlights the importance of using a range of parameters that target all the biological communities in the biofilm. The PICT method can be regarded as a good tool for assessing anthropogenic environmental contamination, but it is necessary to dissociate the real impact of toxicants from environmental factors. [Copyright &y& Elsevier]

• Investigation of the effect of gender and personality on perceiving game elements. • The experiment was conducted in a public university with 189 undergraduate students who took three online gamified courses, based on the self-determination theory, during two academic years. • Gender and personality can affect students' perceptions toward different game elements. • Gender moderates the effect of personality on students' perception of the implemented game elements. While many studies have reported the effectiveness of gamification in motivating students and making learning more fun, some others have reported contradictory findings regarding the potential of implementing game elements in an online gamified course. It is recognized that designing a successful gamification is a challenging process. Previous studies have shown that students' individual differences may impact their gamification experiences. This study complements the available body of research by examining the effect of gender and personality differences on students' perception of gamification in education. An experiment was conducted in a public university with 189 undergraduate students who took three online gamified courses, based on the self-determination theory, during two academic years. The results showed that gender and personality can affect students' perception of specific game elements. For instance, females are more likely to find feedback useful than males. Additionally, students low in extraversion are more likely to find a progress bar useful than students high in extraversion. The results also showed that gender moderates the effect of personality on students' perception of the implemented game elements. For instance, males low in extraversion are more likely to perceive badges' usefulness in gamified courses than males high in extraversion, whereas females low in conscientiousness are more likely to enjoy feedback than females high in conscientiousness. The findings of this study can help designers and educators personalize their gamified courses' design based on personality and gender. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study was undertaken to highlight the potential ecotoxicological impact of the herbicide diuron on biofilms during flooding events in a small river (Morcille) in the Beaujolais vineyard area (France). We investigated the responses of chronically contaminated biofilms exposed to short-term pulses (3h) of diuron. Biofilms were grown in indoor microcosms that were either non-contaminated or exposed to low-level chronic contamination, and not exposed, or exposed to single or double pulses of two environmental concentrations (7 and 14μgL−1) of diuron. Exposure to pollution and its impact on biofilms were assessed by measuring pesticide concentrations in biofilms, biomass parameters (chl a, AFDW), community structure (using 18S and 16S rDNA gene analysis by DGGE, and HPLC pigment analysis to target eukaryotes, bacteria and photoautotrophs, respectively) and by performing a physiological test. Control biofilms displayed very low diuron concentrations, whereas the herbicide was found in the contaminated biofilms. Nevertheless, diuron concentrations were not higher in the pulsed biofilms than in the non-pulsed ones. AFDW and chl a in vivo fluorescence increased in both microcosms during the experiment and biomass was higher in chronically exposed biofilms than in control ones. The impact on biomass was higher for the control double-pulsed biofilms than for the non-pulsed ones. Carbon incorporation by the chronically exposed biofilms was greater during the first 28 days of growth than during the first 28 days of growth in the control biofilms. Both single and double pulses inhibited carbon incorporation of all biofilm communities, especially of the control ones. Short-term inhibition of photosynthesis was never significantly different in exposed and non-exposed biofilms. Few differences in the pigment structure were found between chronically exposed and control biofilms, but pulses impacted on the pigment structure of all biofilm communities. Bacterial structural differences were observed between single-pulsed and non-pulsed biofilms, but not between double-pulsed and non-pulsed biofilms. The different pulses affected the eukaryotic community structures of the control biofilms, but not of the chronically exposed ones. Unlike the bacterial communities, the control eukaryotic communities were structurally different from the chronically exposed ones. This preliminary experimental study indicates that exposure to environmental concentrations of diuron and other agricultural contaminants and further exposure to diuron can have measurable effects on small river biofilm communities. The effects of a pulsed acute exposure to diuron on biofilms depended on whether the biofilms had previously been exposed to the same stressors or not. [Copyright &y& Elsevier]

Abstract Blockchain is becoming a core technology in all application domains as it brings several advantages, such as immutability, transparency, high availability, strong data consistency, and interoperability. Despite these advantages, blockchain systems still have several concerns that might significantly reduce their effectiveness, including motivational, human concerns and miners’ involvement and participation. Gamification, on the other hand, was proposed as a solution for these concerns, among others. However, little is known in the literature on the use of gamification for blockchain systems, calling for more investigation in this regard. Therefore, this study conducts a systematic literature review to investigate why and how gamification is used in blockchain systems. Specifically, 41 studies were included and analyzed in this systematic review. The obtained results highlighted that gamification is integrated into blockchain systems to achieve different purposes, including motivating users/miners and increasing data validation and trust. Additionally, the findings revealed that Ethereum is the most used blockchain platform, where points and challenges are the most used game elements in blockchain systems. Furthermore, when using gamification as an incentive mechanic in blockchain, there is no difference in the effect of the consensus algorithm on miners’ motivation. The findings of this study provide insights into the ways of integrating gamification to enhance blockchain systems, as well as reveal future research directions to consider before deploying the next generation of gamified blockchain systems. [ABSTRACT FROM AUTHOR]

Background: Peritoneal cystic echinococcosis happens usually after traumatic rupture or after surgical treatment. Primary peritoneal cystic echinococcosis is a very rare case that constitutes a diagnostic and therapeutic challenge. Case report: A 30-year-old Tunisian man was admitted for hypogastric pain since 4 months. He has a 10 cm hypogastric mass. Biological-tests were normal. A computed tomography Scan showed a cystic mass on the pelvis measuring 13 × 17 cm without echinococcosis cyst in the liver. The patient was operated and we found a cystic mass of 17 cm located on the Douglas cul-de-sac that suggest a pelvic hydatid cyst. We have performed an aspiration of the cyst confirms the diagnosis followed by injection of hypertonic solution, extarction of the germinal layer and a maximal reduction of the pericyst. The postoperative course was uneventful. Conclusion: Trough our case, we try to focus on the diagnosis and therapeutic options of this rare entity that we should think of in front of a patient with isolated peritoneal cyst especially in endemic country. [ABSTRACT FROM AUTHOR]

Climate change, biodiversity loss, and chemical pollution are planetary‐scale emergencies requiring urgent mitigation actions. As these "triple crises" are deeply interlinked, they need to be tackled in an integrative manner. However, while climate change and biodiversity are often studied together, chemical pollution as a global change factor contributing to worldwide biodiversity loss has received much less attention in biodiversity research so far. Here, we review evidence showing that the multifaceted effects of anthropogenic chemicals in the environment are posing a growing threat to biodiversity and ecosystems. Therefore, failure to account for pollution effects may significantly undermine the success of biodiversity protection efforts. We argue that progress in understanding and counteracting the negative impact of chemical pollution on biodiversity requires collective efforts of scientists from different disciplines, including but not limited to ecology, ecotoxicology, and environmental chemistry. Importantly, recent developments in these fields have now enabled comprehensive studies that could efficiently address the manifold interactions between chemicals and ecosystems. Based on their experience with intricate studies of biodiversity, ecologists are well equipped to embrace the additional challenge of chemical complexity through interdisciplinary collaborations. This offers a unique opportunity to jointly advance a seminal frontier in pollution ecology and facilitate the development of innovative solutions for environmental protection. [ABSTRACT FROM AUTHOR]

Plastics, especially microplastics (<5 mm in length), are anthropogenic polymer particles that have been detected in almost all environments. Microplastics are extremely persistent pollutants and act as long-lasting reactive surfaces for additives, organic matter, and toxic substances. Biofilms are microbial assemblages that act as a sink for particulate matter, including microplastics. They are ubiquitous in freshwater ecosystems and provide key services that promote biodiversity and help sustain ecosystem function. Here, we provide a conceptual framework to describe the transient storage of microplastics in fluvial biofilm and develop hypotheses to help explain how microplastics and biofilms interact in fluvial ecosystems. We identify lines of future research that need to be addressed to better manage microplastics and biofilms, including how the sorption and desorption of environmental contaminants in microplastics affect biofilms and how microbial exchange between microplastics and the biofilm matrix affects biofilm characteristics like antibiotic resistance, speciation, biodiversity, species composition, and function. We also address the uptake mechanisms of microplastics by consumers and their propagation through the food web. [ABSTRACT FROM AUTHOR]

The severe acute respiratory syndrome coronavirus 2 (SARS COV2) had rapidly spread and caused a global pandemic worldwide. The most common symptoms in adults are respiratory with dry cough, dyspnea, and fever. Occasionally, extra-respiratory presentations may be seen such as gastrointestinal involvement with diarrhea, vomiting or abdominal pain. Acute intestinal intussusception is the most common cause of bowel obstruction in infants (2–4 months of age) but rarely could it be encountered in adult. It is a very rare gastro-intestinal manifestation of COVID-19 with an invagination of a segment of the bowel within a more distal one. The part that prolapses into the other is called the intussusceptum, and the part that receives it is called the intussuscipiens. Most of COVID-19 cases of AII are reported in the pediatric population between 4 and 10 months. Only a single case of small bowel obstruction secondary to ileo-colic intussusception in a COVID-19 infection adult was published on April 2021. We present here a challenging case of intussusception secondary to COVID-19 infection in an adult in the absence of respiratory symptoms. Our study presents the first case in Africa of AII in adult patients due to COVID-19. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNP) are increasingly used as antimicrobials in consumer products. Subsequently released into aquatic environments, they are likely to come in contact with microbial communities like periphyton, which plays a key role as a primary producer in stream ecosystems. At present, however, very little is known about the effects of nanoparticles on processes mediated by periphyton communities. We assessed the effects of citrate-coated silver nanoparticles and silver ions (dosed as AgNO3) on five functional end points reflecting community and ecosystem-level processes in periphyton: photosynthetic yield, respiration potential, and the activity of three extracellular enzymes. After 2 h of exposure in experimental microcosms, AgNP and AgNO3 inhibited respiration and photosynthesis of periphyton and the activities of two of the three extracellular enzymes. Addition of a chelating ligand that complexes free silver ions indicated that, in most cases, toxicity of AgNP suspensions was caused by Ag(l) dissolved from the particles. However, these suspensions inhibited one of the extracellular enzymes (leucine aminopeptidase), pointing to a specific nanopartide effect independent of the dissolved Ag(l). Thus, our results show that both silver nanoparticles and silver ions have potential to disrupt basic metabolic functions and enzymatic resource acquisition of stream periphyton. [ABSTRACT FROM AUTHOR]

Blended Learning (BL) is one of the most used methods in education to promote active learning and enhance students' learning outcomes. Although BL has existed for over a decade, there are still several challenges associated with it. For instance, the teachers' and students' individual differences, such as their behaviors and attitudes, might impact their adoption of BL. These challenges are further exacerbated by the COVID-19 pandemic, as schools and universities had to combine both online and offline courses to keep up with health regulations. This study conducts a systematic review of systematic reviews on BL, based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, to identify BL trends, gaps and future directions. The obtained findings highlight that BL was mostly investigated in higher education and targeted students in the first place. Additionally, most of the BL research is coming from developed countries, calling for cross-collaborations to facilitate BL adoption in developing countries in particular. Furthermore, a lack of ICT skills and infrastructure are the most encountered challenges by teachers, students and institutions. The findings of this study can create a roadmap to facilitate the adoption of BL. The findings of this study could facilitate the design and adoption of BL which is one of the possible solutions to face major health challenges, such as the COVID-19 pandemic. [ABSTRACT FROM AUTHOR]

Introduction: the treatment of large biliocystic fistulas is not unanimous among authors in the absence of consensus or a high level of evidence. There is a controversy over the use of a radical approach which allows the fistula to be sutured in a healthy area or conservative treatment that poses repair issues. The purpose of this study is to compare different conservative techniques to treat large biliocystic fistulas. Methods: we conducted a retrospective study of 54 patients with large fistulas in the Department of General Surgery at the Habib Bourguiba University Hospital in Sfax over a period of 9 years (2010 - 2018). Results: fourty-four patients were enrolled in the study. Abdominal ultrasound suggested opening of the bile ducts in 18 cases (47.4%) while computed tomography (CT) scan suggested opening in 28 patients (68.3%). The treatment of fistulas was based on DITFO (internal trans-fistulary drainage) in 18 cases (33.3%), cystobiliary disconnection (PERDROMO) in 11 cases (20.4%) and bipolar drainage in 25 cases. Specific surgical morbidity rate was 31.5% and it was dominated by postoperative biliary fistula in 18.5% of cases. DITFO technique was associated with shorter hospital stay (p=0.028) and lower morbidity rates (22.2%) with no statistically significant difference. Conclusion: DITFO technique is the gold standard technique in the treatment of biliocystic fistula because it is associated with lower morbidity rates and the shortest hospital stay. [ABSTRACT FROM AUTHOR]

Regarding the huge size of the stomal prolapse, a computed tomography (CT) showed a Strangulated peristomal eventration. In this case, clinical examination cannot distinguish it from strangulated stomal prolapse and we insist that we should perform a CT scan in front of a huge stomal prolapse to eliminate the diagnosis of strangulated eventration into a stomal prolapse. [Extracted from the article]

The enrichment of ecosystems by nutrients such as nitrogen (N) and phosphorus (P) has important ecological consequences. These include effects on plant litter decomposition in forest soils and forested headwater streams, where fungi play a pivotal role. However, our understanding of nutrient relationships on fungal communities associated with decomposing litter remains surprisingly incomplete. We conducted a fully factorial microcosm experiment with known communities of fungal decomposers from streams to assess the importance of dissolved N and P supply, as well as the atomic nutrient ratio (N:P), on fungal community succession, diversity, biomass and reproduction on three leaf-litter species differing in nutrient and lignin concentrations. Fungal biomass accrual and spore production were strongly controlled by external N supply, whereas P supply was much less important. The magnitude of these effects was mediated by litter quality, with stronger effects of dissolved N and P on lignin-poor and high N:P litter. N supply also influenced fungal diversity and species composition, acting as a pacemaker of community succession. Collectively, our data indicate that N was in much greater demand than predicted by standard stoichiometric models. The most parsimonious explanation for this deviation relates to the need of litter fungi to invest large amounts of N into degradative exoenzymes. [ABSTRACT FROM AUTHOR]

• Wastewater induced a decrease in C:N and C:P molar ratio in periphyton. • Wastewater microorganisms induced changes in the respiration profiles of periphyton. • Wastewater microorganisms induced higher tolerance of periphyton to micropollutants. • Colonization of periphyton by wastewater prokaryotes is higher than by eukaryotes. • Wastewater microorganisms decreased diatoms abundance in periphyton. Effluents of wastewater treatment plants can impact microbial communities in the receiving streams. However, little is known about the role of microorganisms in wastewater as opposed to other wastewater constituents, such as nutrients and micropollutants. We aimed therefore at determining the impact of wastewater microorganisms on the microbial diversity and function of periphyton, key microbial communities in streams. We used a flow-through channel system to grow periphyton upon exposure to a mixture of stream water and unfiltered or ultra-filtered wastewater. Impacts were assessed on periphyton biomass, activities and tolerance to micropollutants, as well as on microbial diversity. Our results showed that wastewater microorganisms colonized periphyton and modified its community composition, resulting for instance in an increased abundance of Chloroflexi and a decreased abundance of diatoms and green algae. This led to shifts towards heterotrophy, as suggested by the changes in nutrient stoichiometry and the increased mineralization potential of carbon substrates. An increased tolerance towards micropollutants was only found for periphyton exposed to unfiltered wastewater but not to ultra-filtered wastewater, suggesting that wastewater microorganisms were responsible for this increased tolerance. Overall, our results highlight the need to consider the role of wastewater microorganisms when studying potential impacts of wastewater on the receiving water body. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Soil ecosystem services need to monitor soil quality in terms of soil functions. This need in turn requires functional indicators. Microbial functional diversity offers a way to characterize soil quality and any changes to it. Among soil microbial communities, fungi play a critical role in organic matter decomposition and nutrient cycling in soil by decomposing complex substrates, but only a few studies have focused on the function of soil fungal communities. We have developed a protocol based on substrate-induced respiration using the MicroResp™ technique combined with a selective inhibition (SI) procedure to characterize the fungal biomass and catabolic profiles for soil microbial and fungal communities: the FungiResp method. After comparisons with oxytetracycline, we chose bronopol as a bactericide to extend the FungiResp protocol. An optimal bronopol concentration of 78μgg−1 soil was selected for the four soils tested to minimize the risk of inhibiting non-target communities (fungi). We used this convenient, miniaturized method to compare different soils and different perturbations (drought and heat). The FungiResp method gave further data on the fungal part of the microbial substrate-induced respiration in these different contexts. Also, the catabolic structure of microbial and fungal communities measured as pattern of substrate utilization (CLPPs) enabled us to contrast the functional contributions of the decomposer groups in the different soils studied and highlight the functional impacts of the different perturbations applied to them. [Copyright &y& Elsevier]

Fluvial biofilms are subject to multistress situations in natural ecosystems, such as the co-occurrence of light intensity changes and metal toxicity. However, studies simultaneously addressing both factors are rare. This study evaluated in microcosm conditions the relationship between short-term light intensity changes and Zn toxicity on fluvial biofilms with long-term photoacclimation to different light conditions. Biofilms that had long-term photoacclimation to 25 μmol photons · m−2 · s−1 (low light [ LL] biofilms), 100 μmol photons · m−2 · s−1 (medium light [ ML] biofilms), and 500 μmol photons · m−2 · s−1 (high light [ HL] biofilms) were characterized by different structural (Chlorophyll-a [Chl-a], total biomass- AFDW, EPS, algal groups, and diatom taxonomy) and physiological attributes ( ETR- I curves and photosynthetic pigments). HL biofilms showed higher light saturation intensity and a higher production of xanthophylls than LL biofilms. In contrast, LL biofilms had many structural differences; a higher proportion of diatoms and lower AFDW and EPS contents than ML and HL biofilms. A clear effect of light intensity changes on Zn toxicity was also demonstrated. Zn toxicity was enhanced when a sudden increase in light intensity also occurred, mainly with LL biofilms, causing higher inhibition of both the Φ′PSII and the ΦPSII. A decoupling of NPQ from de-epoxidation reaction ( DR) processes was also observed, indicating substantial damage to photoprotective mechanisms functioning in biofilms (i.e., xanthophyll cycle of diatoms) due to Zn toxicity. This study highlights the need to take into account environmental stress (e.g., light intensity changes) to better assess the environmental risks of chemicals (e.g., metals). [ABSTRACT FROM AUTHOR]

Abstract: With the aim of evaluating cause-effect relationships between metal pollution and biofilm structure and function, a translocation study was performed in a metal-polluted stream (the Osor stream “la riera d’Osor”, NE Spain). Biofilm responses were measured as temporal changes in chl-a fluorescence parameters, pigment composition and diatom species composition. Biofilms from a non-polluted site were translocated to four downstream sites presenting a gradient of metal pollution, corresponding to scenarios of low and moderate metal pollution. Metal effects (Zn bioaccumulation, Fe bioaccumulation and Zn in water) were distinguished from other stressors (phosphate concentration in water). Based on the results obtained, a fast bioaccumulation of Zn (after few hours of exposure) was linked to a decrease in photosynthetic efficiency and an enhancement of mechanisms of protection through the xanthophyll cycle. After longer exposure, differences in Zn and Fe bioaccumulation and Zn water concentration between sites were linked to diatom community changes; decrease in diatom cell biovolume, along with a decrease in the IPS index of diatoms. Based on our results, we recommend including Zn in the list of priority pollutant substances of the European Water Framework Directive (2000/60/EC), due to its occurrence and toxicity. In addition, our study supports the use of chl-a fluorescence parameters together with the analysis of photosynthetic pigments of biofilms as suitable functional endpoints of early toxicity. Furthermore, diatom community studies are recommended for their clear response after chronic exposure. However, new diatom indices beyond the use of the IPS are required to increase their sensitivity to metal pollution, e.g. to identify the damage caused by moderate to low metal pollution. [Copyright &y& Elsevier]