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Introduction
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Publications
Publications (79)
Abstract
Aim
To evaluate the patterns of stream diatom beta diversity in islands vs. continents across scales, to relate community similarities with spatial and environmental distances and to investigate the role of island characteristics in shaping insular diatom beta diversity.
Location
Africa, America, Europe, and Pacific.
Time period
Present....
Motivation: Freshwater ecosystems have been heavily impacted by land-use changes, but syntheses on the impacts on freshwater ecosystems are still limited. Here, we compiled a global database encompassing 248 studies with species abundance data (from multiple taxon groups and geographic locations) across sites with different land-use categories. Thi...
Recent research on diatom metacommunities has focused on disentangling the assembly mechanisms driving species and functional composition and biodiversity across space and time, including deterministic (environmental filtering and biotic interactions) and stochastic processes (dispersal and ecological drift). In this chapter, we provide an overview...
The Water Framework Directive (WFD) requires member states to routinely assess the river ecological status using community-based indices. However, there is still a lack of published WFD-compliant methods for the French West Indies, especially using diatom-based indices. Martinique and Guadeloupe exhibit diverse landscapes shaped by their complex ge...
Aim: Understanding the roles of deterministic and stochastic processes in community assembly is essential for gaining insights into species biogeographical patterns. 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 sh...
Eutrophication impairs lake ecosystems at a global scale. In this context, as benthic microalgae are well-established warnings for a large range of stressors, particularly nutrient enrichment, the Water Framework Directive required the development of diatom-based methods to monitor lake eutrophication. Here, we present the diatom-based index we dev...
Le projet AQUAVIT vise à accompagner l'évolution des modalités de gestion des lacs de la façade Atlantique, en Aquitaine, en tant qu'espaces supports d'activités récréatives et touristiques, confrontés à des enjeux environnementaux liés aux colonisations par les plantes aquatiques invasives. Une démarche pluridisciplinaire, associant les sciences h...
While it is recognized that biodiversity currently declines at a global scale, we still have an incomplete understanding of local biodiversity trends under global change. To address this deficiency, we examined the recent decadal trends in water quality and biodiversity (taxonomic and functional) of key river organisms (diatoms, macroinvertebrates...
Les plans d’eau sont des écosystèmes complexes, multifonctionnels et, en même temps, fragiles. Ces milieux aquatiques fournissent de nombreux services écosystémiques, en
assurant des fonctions de support (production primaire, biodiversité), de régulation (épuration des nutriments, régulation des flux hydriques), d’approvisionnement (eau potable, ir...
Patterns in community composition are scale‐dependent and generally difficult to distinguish. Therefore, quantifying the main assembly processes in various systems and across different datasets has remained challenging. Building on the PER‐SIMPER method, we propose a new metric, the dispersal–niche continuum index (DNCI), which estimates whether di...
Le projet de recherche AquaVIT vise à accompagner l’évolution des modalités de gestion des grands lacs aquitains, confrontés à des enjeux environnementaux liés à la colonisation par les plantes aquatiques invasives. Ces plantes exotiques à caractère envahissant peuvent occuper une place importante au sein des écosystèmes lacustres et, par la même o...
Mass effect, allowing species to persist in unfavourable habitats, and dispersal limitation, preventing species from reaching favourable habitats, are the two major dispersal processes. While dispersal limitation can be detected by experimental or modelling techniques, mass effect is more challenging to evaluate, which hampers our ability to disent...
The restoration and the preservation of aquatics ecosystems is a critical issue in our contemporary society. In
lake ecosystems, phytoplankton taxonomic-based indicators have been developed to evaluate water quality, but
suffer of limited ecosystem ecological value. The recent development of functional approaches may allow to
evaluate other aspects...
Aim
The interaction of land use with local versus regional processes driving biological homogenization (β‐diversity loss) is poorly understood. We explored: (a) stream β‐diversity responses to land cover (forest versus agriculture) in terms of physicochemistry and physicochemical heterogeneity; (b) whether these responses were constrained by the re...
Freshwater is presently under a range of increasing pressures, some of which are directly due to anthropogenic activities as agricultural practices or urban activites and may have effects on aquatic organisms, even at low concentration levels. Biofilms are communities of microorganisms (bacteria, algae, protozoa, fungi) and meiofaune integrated in...
Autoecological traits of aquatic organisms are well known to provide crucial information on hydrosystems and
are good complements to biotic indices for evaluating surface water ecological quality. In France, as in many
other European countries, autoecological approaches concerning diatoms are based on a checklist developed in
the Netherlands. While...
Niche conservatism (NC) describes the scenario in which species retain similar characteristics or traits over time and space, and thus has potentially important implications for understanding their biogeographic distributions. Evidence consis- tent with NC includes similar niche properties across geographically distant regions. We investigated whet...
The Water Framework Directive (WFD) requires a level of “confidence” and “precision” in the established freshwater monitoring system, as several sources of variability can contribute significantly to the misclassification of water body ecological status. Diatoms and macrophytes are required by the Directive as biological quality element (BQE) and are...
Resilience in river ecosystems requires that organisms must persist in the face of highly dynamic hydrological and geomorphological variations. Disturbance events such as floods and droughts are postulated to shape life history traits that support resilience, but river management and conservation would benefit from greater understanding of the emer...
Aim
To quantify the relative contributions of local community assembly processes versus γ‐diversity to β‐diversity, and to assess how spatial scale and anthropogenic disturbance (i.e. nutrient enrichment) interact to dictate which driver dominates.
Location
France and the United States.
Time period
1993–2011.
Major taxa studied
Freshwater stream...
Exotic hydrophytes are often considered as aquatic weeds, especially when forming dense mats on an originally poorly colonized environment. While management efforts and research are focused on the control and on the impacts of aquatic weeds on biodiversity, their influence on shallow lakes’ biogeochemical cycles is still unwell explored. The aim of...
Dates and hours of sampling at different sites of the Lacanau Lake. The complete physicochemical database is reported.
In this intercontinental study of stream diatoms, we asked three important but still unresolved ecological questions: (1) What factors drive the biogeography of species richness and species abundance distribution (SAD)? (2) Are climate-related hypotheses, which have dominated the research on the latitudinal and altitudinal diversity gradients, adeq...
Niche conservatism (NC) describes the scenario in which species retain similar characteristics or traits over time and space, and thus has potentially important implications for understanding their biogeographic distributions. Evidence consistent with NC includes similar niche properties across geographically distant regions. We investigated whethe...
Climate, by altering the spatio-temporal distributions of suitable habitats, leads to modifications in a multitude of species ranges. In recent years, the ability of species to adjust to changing climatic conditions is of growing concern. In the present study, a generic trait-based method to assess species exploratory potential under climate change...
The ecology and taxonomy of the epilithic diatom flora of the Agnéby River, Ivory Coast were studied in 2012. Ten sites were investigated and diatoms were sampled on glass slides immersed for a period of 30 days during the wet and dry seasons. Physico-chemical parameters were measured at each site while sampling diatoms. Five taxa were largely domi...
Niche conservatism (NC) describes the scenario in which species retain similar characteristics or traits over time and space, and thus has potentially important implications for understanding their biogeographic distributions. Evidence consistent with NC includes similar niche properties across geographically distant regions. We investigated whethe...
Le pourcentage de déformations des diatomées est de plus en plus utilisé comme un indicateur de stress toxique dans les cours d’eau. Cependant, ce pourcentage ne permet pas de quantifier directement l’importance de ce stress, et certains auteurs suggèrent que la quantification de la « sévérité » des déformations pourrait améliorer les relations de...
Exotic hydrophytes are often considered as aquatic weeds, especially when forming dense mats on an originally poorly-colonized environment. While management efforts and research are focused on the eradication and/or on the impacts on the biodiversity, their influence on ecosystem functioning of shallow lakes is still poorly explored. Indeed, as a r...
Benthic diatoms have been widely used to assess the ecological status of freshwater ecosystems, especially in the context of recent international water framework directive policies (e.g. the WFD). Despite diatom-based indices are known to respond fastly to water quality degradation, they are not designed to precisely identify the nature of pressure...
Species cooccurrence patterns give significant insights into the processes shaping communities. While biotic interactions have been widely studied using cooccurrence analyses in animals and larger plants, studies about cooccurrences among micro-organisms are still relatively rare. We examined stream diatom cooccurrences in France through a national...
This issue contains, as part of a focus on diatoms, some of the contributions presented at the 34th Symposium of the Association des Diatomistes de Langue Française (ADLaF) held in Bordeaux. This French-speaking society, funded in 1980, promotes diatom research and facilitates, through its annual symposium and its website (http:// adlaf.free.fr/),...
Aim
To examine species and trait composition in stream diatoms along environmental, climatic and spatial gradients and to ascertain if the use of different levels of biological organization is beneficial for investigating global environmental changes and the role of history in structuring communities.
Location
Global cover with datasets from the A...
Since bioolms integrate the environmental eeects of water chemistry, along with the physical and geomorphological characteristics of rivers and lakes, they have been widely applied in biomoni-toring. In particular, diatoms are extensively used as reliable environmental indicators. Diatoms are microscopic, unicellular brown algae, which ooen dominat...
Since biofilms integrate the environmental effects of water chemistry, along with the physical and geomorphological characteristics of rivers and lakes, they have been widely applied in biomonitoring. In particular, diatoms are extensively used as reliable environmental indicators. Diatoms are microscopic, unicellular brown algae, which often domin...
Background and aims – The diatom flora from West African rivers remains virtually unknown. In this context, and given the restricted literature for the region, we explored the diatom communities from the Agnéby and Mé river watersheds, Ivory Coast.
Methods – Diatoms were sampled on glass slides previously immersed during a period of thirty days, a...
Eleven European countries participated in an exercise to harmonise diatom-based methods used for status assessment in lakes. Lakes were divided into low, medium and high alkalinity types for this exercise. However, it was not possible to perform a full intercalibration on low alkalinity lakes due to the short gradient and confounding factors. Value...
The River Luzou flows through a sandy substrate in the South West of France. According to the results of two assessment surveys, the Water Agency appraised that this river may not achieve the good ecological status by 2015 as required by the Water Framework Directive (2000/60/EC). This ecosystem is impacted by industrial effluents (organic matter,...
Authors of several studies of the spatial distributions of microorganisms have shown strong geo-
graphical patterns and stressed the importance of considering the spatial component explicitly when studying
assemblage–environment relationships. The processes underlying the patterns are still under debate because it is difficult to separate the uniqu...
Owing to the high complexity of diatom community data, there is a special need for methods accounting for complex non-linear gradients. A Kohonen’s self-organizing map (SOM) is a neural network with unsupervised learning. It allows both unbiased classification of the communities and visualization of biological gradients on a two-dimensional plane....
Après une présentation des besoins en matière d'évaluation de la qualité des milieux aquatiques continentaux, ce document présente l'état de l'art sur le développement des bioindicateurs tels qu'il a été présenté lors du séminaire organisé par l'Onema les 19 et 20 avril 2011 à Paris. Il s'agit donc d'une synthèse des journées "DCE et bioindication"
In 2009, seventeen analysts participated in a pan-European diatom ring-test (intercalibration), analyzing nine samples from seven countries following the European standard EN 14407. The objective of this exercise was to agree on practical conventions on diatom identification to facilitate future intercalibration work and to assess the extent to whi...
The Mediterranean Rivers Geographic Intercalibration Group developed a 3-step approach that allowed the characterization of the best available condition of four Mediterranean common stream types, regarding organic contamination and nutrients, hydrological and morphological alterations and land use. For this purpose, a common database composed of 7...
Les cartes auto-organisatrices de Kohonen appliquées à l'étude des communautés de micro-algues des cours d'eau
The Leyre River is the main tributary to the Bassin d'Arcachon lagoon. Herbicides belonging to the chloroacetanilide class have been found in the river (S-metolachlor and acetochlor) as well as some of their metabolites at higher concentrations. As the environmental toxicity of these molecules is not well known, ecotoxicological tests have been car...
page/terms-and-conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any re...
A total of 118 benthic diatom taxa were recorded during a survey in 2007 of the Kebir-East wadi, north-eastern Algeria. Fourteen samples were collected at seven sampling stations in winter and summer. The majority of diatom taxa comprised cosmopolitan species widely distributed along the hydrosystem. Canonical correspondence analysis, used to exami...
The European Union (EU) Water Framework Directive depends, for effective implementation, on Member
States (MSs) agreeing to a concept of the unimpacted “reference” state, which will then provide
the “expected” value in Ecological Quality Ratio (EQR) calculations. Reference assemblages of organism
groups will, in turn, vary, due to geological, hydro...
L'Indice Diatomique Réunion (IDR) est un nouvel outil de bioindication, destiné à l'évaluation de la qualité biologique des cours d'eau de l'île de la Réunion à partir de la composition spécifique des communautés locales de diatomées benthiques. Cet outil a été développé conjointement par Asconit et l'Irstea, dans le cadre d'un programme de Recherc...
L'indice biologique diatomées (IBD) est un indice de qualité d'eau des rivières. Normalisé en 2000 puis révisé en 2007, il est basé sur le recueil et l'observation des fl ores de diatomées benthiques. Son calcul repose sur la prise en compte de la présence, de l'abondance et de la sensibilité d'espèces clés. Historiquement, cet indice a été mis au...
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 perspe...
The Biological Diatom Index (BDI) is a standardized method routinely used in France for the surveillance of watercourse quality. This index is based on a list of 209 key species showing different pollution sensitivities. The pollution sensitivity, or “ecological profile”, is determined through the species presence probability values along a seven q...
The European Union (EU)’s Water Framework Directive (WFD) requires that all Member States participate in intercalibration
exercises in order to ensure that ecological status concepts and assessment levels are consistent across the EU. This paper
describes one such exercise, performed by the countries in the Central/Baltic Geographical Intercalibrat...
Cette classification (Tab. 1) prend pour modèle celle qui a été publiée par Round et al. en 1990. Cependant, pour les niveaux nomenclaturaux plus élevés, elle a été modifiée en suivant les résultats des travaux de phylogénie moléculaire de Medlin et Kaczmarska (2004). Le tableau 1 décline la division des Bacillariophyta en 10 niveaux nomenclaturaux...
Community structure changes with pollution or stress. In the Water Framework Directive, high ecological status through biological parameters is defined as a slight or minor deviation from the reference community, while the good status is defined as a small deviation.To assess the importance of this deviation, and then to measure the degradation of...
High altitude rivers in European mountains show a large diversity of benthic diatom assemblage. Diatoms were studied from rivers of the Alps, the Pyrenees, the Massif Central and the Iberic system. The first aim of this study was to assess the importance of these ecoregions for diatoms compared to other environmental factors. To reduce the heteroge...
Distinguishing natural variations from human related changes becomes crucial in assessment, maintenance and restoration of aquatic ecosystems. The present work aims to focus on variation in the biogeographical frame of diatom assemblages in natural or near-natural conditions. First, 233 diatom samples collected from clean to less disturbed sites of...
Ecological communities consist of a large number of species. Most species are rare or have low abundance, and only a few are abundant and/or frequent. In quantitative community analysis, abundant species are commonly used to interpret patterns of habitat disturbance or ecosystem degradation. Rare species cause many difficulties in quantitative anal...
A relational database linking benthic diatom records, taxonomic nomenclature including synonyms, and corresponding environmental
data has been built in MS Access. It allowed flexible and long-term use of a relatively important amount of data (∼3000 records)
gathered in the framework of the EC-funded PAEQANN project, gathering precise and documented...
By comparing diatom communities in natural and disturbed sites, indicators for different types and levels of anthropogenic disturbance can be found. As a first step, this study aims to describe the different natural and disturbed community types found throughout the French hydrosystem. 836 diatom samples were analysed with an unsupervised neural ne...
A relational database linking benthic diatom records, taxonomic nomenclature including synonyms, and corresponding environmental data has been built in MS Access. It allowed flexible and long-term use of a relatively important amount of data (3000 records) gathered in the framework of the EC-funded PAEQANN project, gathering precise and documented...
1-URBO, Facultés Universitaires N-D de la Paix ; 61, rue de Bruxelles, B-5000 Namur (Belgium) 2-Section of Geography, Université du Québec à Trois-Rivières ; 3351, boulevard des Forges, C.P. 500, Trois-Rivières (Quebec, Canada) G9A 5H7 3-LADYBIO, UMR 5576, CNRS, Université Paul Sabatier ; 118, route de Narbonne, F-31062 Toulouse cedex (France) 4-Ce...
Knowing that diatoms are good indicators of stream ecological conditions, the aim of our research program was to test on a pilot data-set the interest and efficiency of using a Self-Organizing Map (SOM) as an ordination technique to determine and to classify types of river ecosystems. Such neural networks have already been successfully used for oth...
