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La dégradation continue des écosystèmes aquatiques a intensifié le besoin de développer des méthodes d’évaluation de la qualité du milieu toujours plus performantes et pertinentes, basées sur la biologie et l’écologie des organismes. Dans ce contexte, l’utilisation des traits biologiques et écologiques en bio-indication fournit de nombreuses perspectives. Nous vous proposons, à travers l’exemple des diatomées et des macro-invertébrés, de voir comment sont déclinés ces traits bioécologiques en termes de bio-indication toxique.

This article reports on two quantitative studies of English learners' (ELs) interactions with constructed-response items from a Grade 5 state science test. Study 1 investigated the relationships between the constructed-response item-level variables of English Reading Demand, English Writing Demand, and Background Knowledge Demand and the performance of ELs vs. non-ELs on those items. English Writing Demand was the strongest predictor of Differential Item Functioning favoring non-ELs over ELs for constructed-response items. In Study 2, we investigated the student-level variable of English language proficiency level and found that lower English language proficiency was related to greatly increased odds of omitting a response to a constructed-response item, even when controlling for science proficiency. These findings challenge the validity of scores on constructed-response test items as measures of ELs' science proficiency.

In this experimental study, 20 multiple-choice test items from the Massachusetts Grade 5 science test were linguistically simplified, and original and simplified test items were administered to 310 English learners (ELs) and 1,580 non-ELs in four Massachusetts school districts. This study tested the hypothesis that specific linguistic features of test items contributed to construct-irrelevant variance in science test scores of ELs. Simplifications targeted specific linguistic features, to identify those features with the largest impacts on ELs' test performance. Of all the linguistic simplifications used in this study, adding visual representations to answer choices had the largest positive effect on ELs' performance. These findings have significant implications for the design of multiple-choice test items that are fair and valid for ELs.

Over the last decades, Aquitaine lakes have been exposed to growing biomasses of invasive macrophytes, in particular Lagarosiphon major, and to frequent blooms of the cyanobacteria Microcystis aeruginosa. Our aim was to explore the potential role of L. major in the regulation of such blooms, through allelopathic interactions. Experiments consisted of exponential growth phase cells incubated for 96 h in L. major extracts at increasing concentrations. Our approach was based on untargeted metabolomics and photosynthetic activity measurements.We demonstrated the anticyanobacterial properties of L. major extracts. In particular, we reported that L. major extracts inhibited M. aeruginosa photosynthesis, and affected the production of various metabolite classes and pathways mainly involved in the secondary metabolism of the cyanobacteria.We further provided clear evidence about the existence of metabolite classes in L. major that may be involved in allelopathic interactions with M. aeruginosa, such as caffeic acid.

S'il ne fait aucun doute que la biodiversité décline à l'échelle mondiale, il est surprenant de constater que les dynamiques locales peuvent être contrastées. Nous possédons une compréhension encore incomplète de la façon dont les écosystèmes évoluent sous l'effet du changement global. Ici, nous avons cherché à caractériser la dynamique temporelle récente de la biodiversité des rivières en France, d'un point de vue taxonomique et fonctionnel, concernant différents organismes clés (diatomées, macro-invertébrés et poissons), à partir d’un large panel de mesures de la biodiversité et sur une période multi-décennale. Les résultats convergent vers la mise en évidence d'un retour significatif des taxons sensibles à l'eutrophisation, signe d'amélioration de la qualité des cours d’eau au cours de la période d’étude du point de vue de l’enrichissement trophique. D'autre part, la richesse en diatomées et, dans une moindre mesure, en poissons, a diminué au fil du temps, tandis que la richesse taxonomique des macro-invertébrés a augmenté. Enfin, l'étude a révélé des réarrangements cohérents au sein des communautés des cours d'eau, avec le passage d’une production primaire planctonique à une production primaire benthique, entraînant des modifications fonctionnelles des communautés de macro-invertébrés et de poissons.

Aim: Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into the biogeographical patterns of biodiversity. However, the way community assembly processes operate is still not fully understood, especially in oceanic islands. In this study, we examine the importance of assembly processes in shaping diatom communities in islands and continents, while also investigating the influence of climate and local water chemistry variables on species distributions. Location: Global. Taxon: Stream benthic diatoms. Methods: We used diatom datasets from five continents and 19 islands and applied beta diversity analyses with a null model approach and hierarchical joint species distribution modelling. To facilitate comparisons with continents, we used continental area equivalents (CAEs), which represent continental subsets with comparable areas and the same number of study sites as their corresponding islands counterparts. Results: We found that homogeneous selection (i.e., communities being more similar than the random expectation) was the dominant assembly process within islands whereas stochastic processes tended to be more important within continents. In addition, assembly processes were influenced by study scale and island isolation. Climatic variables showed a greater influence on species distribution than local factors. However, in islands, local environmental variables had a greater impact on the distributions of unique taxa as opposed to non‐unique taxa. Main Conclusions: We observed that the assembly processes of diatom communities were complex and influenced by a combination of deterministic and stochastic forces, which varied across spatial scales. In islands, there was no universal pattern of assembly processes, given that their influence depends on abiotic conditions such as area, isolation, and environmental heterogeneity. In addition, the sensitivity of species occurring uniquely in islands to local environmental variables suggests that they are perhaps less vulnerable to climatic changes but may be more influenced by changes in local physicochemistry. [ABSTRACT FROM AUTHOR]

Early career teachers rarely receive sustained support for addressing issues of diversity and equity in their science teaching. This paper reports on design research to create a 30 hour professional development seminar focused on cultivating the interpretive power of early career teachers who teach science to students from historically non-dominant communities. Interpretive power refers to teachers' attunement to (a) students' diverse sense-making repertoires as intellectually generative in science and (b) expansive pedagogical practices that encourage, make visible, and intentionally build on students' ideas, experiences, and perspectives on scientific phenomena. The seminar sought to integrate student sense-making, scientific subject matter, teaching practice, and matters of equity and diversity on the same plane of professional inquiry by engaging participants in: (a) learning plant science; (b) analyzing classroom cases; (c) experimenting with expansive discourse practices in their classrooms; and (d) analyzing their classroom experiments in relation to student sense-making and expansive pedagogy. Twenty-eight teachers participated in two cycles of design research. An interview-based transcript analysis task captured shifts in teachers' interpretive power through their participation in the seminar. Findings showed that the teachers developed greater attunement to: complexity in students' scientific ideas; the intellectual generativity of students' sense-making; student talk as evidence of in-process, emergent thinking; and co-construction of meaning in classroom discussions. Findings also showed that participants developed deeper understanding of the functions of expansive teaching practices in fostering student sense-making in science and greater commitment to engaging in expansive practices in their classroom science discussions.

This article reports on two quantitative studies of English learners' (ELs) interactions with constructed-response items from a Grade 5 state science test. Study 1 investigated the relationships between the constructed-response item-level variables of English Reading Demand, English Writing Demand, and Background Knowledge Demand and the performance of ELs vs. non-ELs on those items. English Writing Demand was the strongest predictor of Differential Item Functioning favoring non-ELs over ELs for constructed-response items. In Study 2, we investigated the student-level variable of English language proficiency level and found that lower English language proficiency was related to greatly increased odds of omitting a response to a constructed-response item, even when controlling for science proficiency. These findings challenge the validity of scores on constructed-response test items as measures of ELs' science proficiency. [ABSTRACT FROM AUTHOR]

English language learners (ELLs) and their teachers, schools, and communities face increasingly high-stakes consequences due to test score gaps between ELLs and non-ELLs. It is essential that the field of educational assessment continue to investigate the meaning of these test score gaps. This article discusses the findings of an exploratory study of the response processes of grade 5 ELLs and non-ELLs on multiple-choice science test items from a high-stakes test. We found that the ELL students in our sample were more likely than the non-ELL students to answer incorrectly despite demonstrating knowledge of the science content targeted by the test items. Investigating the interview transcripts of ELL students who answered in this way revealed that ELL students' interactions with specific linguistic features of test items often led to alternative interpretations of the items that resulted in incorrect answers. The implications of this work for the assessment of ELLs in science are discussed.

This paper reports a study of the effects of a collaborative inquiry approach to science on language minority students' (middle and high school) learning. This approach emphasizes involiving the students, most of whom have never studied science before and some of whom have had very little schooling of any kind, in "doing science" in ways that practicing scientist do. This study addresses the question: To what extent do students appropriate scientific ways of knowing and reasoning as a result of their participation in collaborative scientific inquiry? We focus our analysis on changes in students, conceptual knowledge and use of hypotheses, experiments, and explanations to organize their reasoning in the context of two think-aloud problems. The findings indicate that at the beginning of the school year the students' reasoning was non-analytic and bound to personal experience. By contrast, at the end of the school year they reasoned in terms of larger explanatory system, used hypothese to organize and give direction to their reasoing, and ddemonstrated and awareness of the function of experimentation in producing evidence to evaluate hypotheses.