126 results on '"Ector, L."'
Search Results
102. Optimization of the replica molding process of PDMS using pennate diatoms.
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Hl&ucute;biková, D., Luís1, A. T., Vaché, V., Ector, L., Hoffmann, L., and Choquet, P.
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PENNALES ,MATHEMATICAL optimization ,PLASMA desorption mass spectrometry ,NANOSTRUCTURED materials ,BIOMIMETIC chemicals ,POLYDIMETHYLSILOXANE ,MOLDING (Founding) - Abstract
Biomimetic fabrication of nanostructured materials has recently attracted the attention of researchers as a cost-effective and easily applicable method of nanotexturing. Different techniques and materials have been used in order to replicate natural patterns, among which polydimethylsiloxane (PDMS Sylgard 184
® ) was recently used to replicate the micro- and nanoscale patterns from centric diatoms. In this paper, we test the reproducibility and precision of this approach using various morphologically different diatom species trying to optimize the molding parameters. The optimization process is focused on immobilization of diatoms on the glass support, which serves as a master for templating, as well as on the parameters of PDMS fabrication such as the ratio of the curing agent and elastomer, use of vacuum, curing time and temperature. The results indicate that higher ratios of curing agent and elastomer, longer curing time and lower temperature are the most favorable conditions to obtain negative diatom replicas of good quality with features of 50 nm. Although this method can give very precise results producing high-resolution molds with all micro- and nanostructures replicated, we revealed some limitations regarding the size and morphology of the species used. These results indicate that large round and flat diatom species seem to be more suitable for the cast molding. [ABSTRACT FROM AUTHOR]- Published
- 2012
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103. Pinnularia aljustrelica sp. nov. (Bacillariophyceae), a new diatom species found in acidic waters in the Aljustrel mining area (Portugal) and further observations on the taxonomy and ecology of P. acidophila Hofmann et Krammer and P. acoricola Hustedt
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Luís, A. T., Maria Helena Novais, Vijver, B., Almeida, S. F. P., Da Silva, E. A. F., Hoffmann, L., and Ector, L.
104. Two short-striated species of Staurosirella (bacillariophyceae) from Indonesia and the United States
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Morales, E. A., Carlos Eduardo Wetzel, and Ector, L.
105. A comparative study of the ecological state of the Ebro watershed rivers by means of macroinvertebrates and diatoms | Estudio comparativo del estado ecológico de los ríos de la cuenca del Ebro mediante macroinvertebrados y diatomeas
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Oscoz, J., Joan Gomà, Ector, L., Cambra, J., Pardos, M., and Durán, C.
106. Two new periphytic Eunotia species from the neotropical Amazonian 'black waters', with a type analysis of E. braunii
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Carlos Eduardo Wetzel, Ector, L., Hoffmann, L., Lange-Bertalot, H., and Bicudo, D. C.
107. Perinotia diamantina Sp. Nov., A new diatom species from the chapada diamantina, Northeastern Brazil
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Ferrari, F., Carlos Eduardo Wetzel, Ector, L., Blanco, S., Viana, J. C. C., Da Silva, E. M., and Campos Bicudo, D.
108. Distribution and ecology of Didymosphenia geminata (Lyngbye) M. Schmidt (Bacillariophyta) in trentino watercourses (Northern Italy)
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Beltrami, M. E., Blanco, S., Ciutti, F., Cappelletti, C., Monauni, C., Pozzi, S., Frédéric Rimet, Ector, L., Ecologia, and Instituto de Medio Ambiente, Recursos Naturales y Biodiversidad de la Universidad de Léon
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Diatomeas ,Biología ,Trento (provincia) ,Didymosphenia geminata ,Ecología. Medio ambiente ,Italia - Abstract
P. 141-160 In 2000 the European Parliament and The European Union Council recommended that member countries assess water quality using diatoms, as part of the phytobenthos. In Italy this recommendation has given new ímpetus to the study of diatom communities and the application of biotic indices. During the summer of 2004, a total of 11 rivers of the Trentino province (Northern Italy) were sampled, revealing the presence in low abundances of the diatom Didymosphenia geminata {Lyngbye) M. Schmidt. The sites where this diatom occurred were characterised by a low pollution impact; they were also lake fed or had a regulated flow regime, although with different geologies. Morphological features of D. gemina/a frustules were analysed using LM and SEM and specimens could be referred to the morphotype "geminata". In many countries this species is expanding its distribution and in New Zealand it is considered an invasive alga. This work provides an initial report on the presence of D. geminara in the Trento province, and contributes to increasing the knowledge on its distribution in Ilaly and its ecology in the Alps SI
109. Luticola deniseae sp. nov. A new epizoic diatom from the Rio Negro (Amazon hydrographic Basin)
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Carlos Eduardo Wetzel, Vande Vijver, B., Ector, L., Observatoire océanologique de Banyuls (OOB), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
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[SDV]Life Sciences [q-bio] ,Biology ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
110. Composition of the epilithic diatom flora from a subtropical river, Southern Brazil
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Bes, D., Ector, L., Lezilda Carvalho Torgan, and Lobo, E. A.
111. Aïn Bou Rkhiss and Aïn Kibrit, two springs from the Merguellil Basin (Kairouan, Central Tunisia): Diatom assemblages, biological polluosensitivity indices, hydrogeology and societal aspects
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Coste, M., Riaux-Gobin, C., Riaux, J., Pablo Saenz-Agudelo, Massuel, S., Ector, L., Calvez, R., Ben Aïssa, N., Centre de recherches insulaires et observatoire de l'environnement (CRIOBE), Université de Perpignan Via Domitia (UPVD)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Excellence CORAIL (LabEX CORAIL), Université des Antilles (UA)-Institut d'écologie et environnement-Université de la Nouvelle Calédonie (UNC)-Université de la Polynésie Française (UPF)-Université de La Réunion (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-École pratique des hautes études (EPHE)-École des hautes études en sciences sociales (EHESS)-Université des Antilles et de la Guyane (UAG)-Institut de Recherche pour le Développement (IRD), Gestion de l'Eau, Acteurs, Usages (UMR G-EAU), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-AgroParisTech-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Instituto de Ciencias ambientales y evolutivas, Universidad Austral de Chile, Environmental Research and Innovation Department, Luxembourg Institute of Science and Technology (LIST), INAT Laboratoire Recherche-Développement Sciences et Technologie de l'Eau (INAT-LRSTE), Université de Carthage - University of Carthage-INAT, Université de Perpignan Via Domitia (UPVD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université des Antilles et de la Guyane (UAG)-École des hautes études en sciences sociales (EHESS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de La Réunion (UR)-Université de la Polynésie Française (UPF)-Université de la Nouvelle-Calédonie (UNC)-Institut d'écologie et environnement-Université des Antilles (UA), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Centre National de la Recherche Scientifique (CNRS), Université de Perpignan Via Domitia (UPVD), UNIVERSIDAD AUSTRAL DE CHILE LOS RIOS CHL, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), INSTITUTE OF SCIENCE AND TECHNOLOGY ERIN BELVAUX LUX, INAT TUNIS TUN, and Böttger, Sonja
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water quality studies ,[SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems ,HYDROGEOLOGY ,Aïn Bou Rkhiss ,[SDV.EE.ECO] Life Sciences [q-bio]/Ecology, environment/Ecosystems ,[SDV.EE.SANT] Life Sciences [q-bio]/Ecology, environment/Health ,[SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM] ,bio geochemical characteristics ,[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology ,[SDV.BBM.BC] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM] ,LUTICOLA ,[SDV.EE.SANT]Life Sciences [q-bio]/Ecology, environment/Health ,[SDV.TOX.ECO] Life Sciences [q-bio]/Toxicology/Ecotoxicology ,Specific Polluosensitivity Index (SPI ,[SDE.IE]Environmental Sciences/Environmental Engineering ,WATER SUPPLIES ,SOCIAL USES AND KNOWLEDGE ,ECOLOGICAL INDICATORS ,Biological Diatom Index (BDI) ,Aïn Kibrit(tunisia) ,bioindicators of water pollution ,[SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM] ,[SDE]Environmental Sciences ,[SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology ,[SDE.IE] Environmental Sciences/Environmental Engineering ,[SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology ,BACILLARIOPHYCEAE - Abstract
International audience; Surveys of the diatom assemblages from Aïn Bou Rkhiss and Aïn Kibrit, two springs that flow out into the Merguellil Wadi, and Aïn Ben Ali, a well located a few kilometers to the east, in the same geological formations (Kairouan district, Central Tunisia), were conducted in 2014 and 2016. The aim of this study was to characterize the species diversity of these water points, establish their ecological status and test the water quality using diatom indices standardized in France [Biological Diatom Index (BDI) and Specific Polluosensitivity Index (SPI)]. Several physical-chemical parameters were measured in 2016. Aïn Bou Rkhiss and Aïn Kibrit are in close proximity to one another but differ in terms of their bio-geochemical characteristics and uses (drinking water for domestic use and sulfur-rich water). We discuss the population’s growing anxiety with respect to their water supply and explore the traditional knowledge concerning the region’s groundwater circulation. The BDI index, reveals a lower quality than that assumed by local users. This may be due to a lack of knowledge about some other local water supplies of good quality that would have served as reference, and inadequacy of these methods designed for European freshwaters without consideration of more southern diatoms. A new variety of Luticola is described.
112. Bioindication by epilithic and epiphytic diatoms in the Sûre River (Luxembourg),Bioindication par les diatomées épilithiques et épiphytes dans la Rivière Sûre (Luxembourg)
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Torrisi, M., Rimet, F., Henry-Michel Cauchie, Hoffmann, L., and Ector, L.
113. Eolimna becaresii sp. nov., a new diatom taxon from a Spanish Shallow Lake
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Blanco, S., Maria Helena Novais, Hoffmann, L., and Ector, L.
114. Influence of Source Pollution on Diatoms in 1st and 2nd Order Headwaters (Senne Catchment, Belgium)
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Van Onsem, Stijn, Foy, Theresia, Triest, Ludwig, Ector, L., Hlúbiková, D., Cauchie, H.-m., Hoffmann, L., General Botany and Nature Management, and Biology
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multiple stressors ,benthic diatoms ,headwaters ,water quality - Abstract
Headwaters in 1st and 2nd order stream catchments can be subject to various environmental stresses in the highly fragmented landscape of Western European lowlands. Headwaters in close vicinity of urbanized zones such as the Brussels Capital region can be impacted close to their sources (Triest et al. , 2001) and may show strong environmental gradients over distances as short as a few kilometers. We studied the response of diatom communities to multiple stressors in 1st and 2nd order streams in the Senne river catchment. These headwaters were predominantly forested, predominantly agricultural or considered as areas of mixed land-uses (partly forested and partly otherwise). Over a three-year period with single sampling per year in spring, 180 diatom taxa were collected at 43 stream sites. Detrended correspondence analysis (DCA), Cluster and TWINSPAN analysis revealed groups of sites with similar species composition and redundant detrended analysis (RDA) indicated a strong gradient effect of species to several key environmental variables. With only 1 km away from the sources, significantly different community patterns existed between stream types, from small forested watersheds (e.g. Achnanthidium minutissimum, Planothidium lanceolatum, and Amphora pediculus) to watersheds in both agricultural areas and mixed landuses (Nitzschia palea, Nizschia capitellata, Luticola mutica and Gomphonema parvulum). Between-year variability in the composition of sensitive species in the forest streams was not significant. The tolerant species Luticola mutica and Gomphonema parvulum were of significantly higher abundances in the disturbed streams. Benthic diatom assemblages were significantly related to stress gradients. Changes in assemblages were associated with a decrease in ecological quality (IBD, IPS and TDI index values; weighted average scores of N, S, H and O values) and environmental variables such as SiO2 and O2 along this gradient. Other environmental variables such as ionic and nutrient concentrations (conductivity, Cl-, DIN, NH4+, NO2- and SRP) increased along the gradients. In subsequent years, we observed three main groups of stressors acting on headwaters close to the sources, namely domestic waste, highway runoffs (including de-icing salts), and predominantly agricultural activities. In forested source areas, the size of the forest perimeter seemed not to be of great importance for maintaining a higher ecological quality of its headwaters. Direct influence from road run-off and from pond water modified the diatom assemblages and lowered the ecological quality of forest streams.
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- 2009
115. Diatom DNA metabarcoding to assess the effect of natural radioactivity in mineral springs on ASV of benthic diatom communities.
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Baker LA, Beauger A, Kolovi S, Voldoire O, Allain E, Breton V, Chardon P, Miallier D, Bailly C, Montavon G, Bouchez A, Rimet F, Chardon C, Vasselon V, Ector L, Wetzel CE, and Biron DG
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- Ecosystem, DNA Barcoding, Taxonomic, Minerals, Diatoms genetics, Radioactivity
- Abstract
Little is still known about the low dose effects of radiation on the microbial communities in the environment. Mineral springs are ecosystems than can be affected by natural radioactivity. These extreme environments are, therefore, observatories for studying the influence of chronic radioactivity on the natural biota. In these ecosystems we find diatoms, unicellular microalgae, playing an essential role in the food chain. The present study aimed to investigate, using DNA metabarcoding, the effect of natural radioactivity in two environmental compartments (i.e. spring sediments and water) on the genetic richness, diversity and structure of diatom communities in 16 mineral springs in the Massif Central, France. Diatom biofilms were collected during October 2019, and a 312 bp region of the chloroplast gene rbcL (coding for the Ribulose Bisphosphate Carboxylase) used as a barcode for taxonomic assignation. A total of 565 amplicon sequence variants (ASV) were found. The dominant ASV were associated with Navicula sanctamargaritae, Gedaniella sp., Planothidium frequentissimum, Navicula veneta, Diploneis vacillans, Amphora copulata, Pinnularia brebissonii, Halamphora coffeaeformis, Gomphonema saprophilum, and Nitzschia vitrea, but some of the ASVs could not be assigned at the species level. Pearson correlation failed to show a correlation between ASV' richness and radioactivity parameters. Non-parametric MANOVA analysis based on ASVs occurrence or abundances revealed that geographical location was the main factor influencing ASVs distribution. Interestingly,
238 U was the second factor that explained diatom ASV structure. Among the ASVs in the mineral springs monitored, ASV associated with one of the genetic variants of Planothidium frequentissimum was well represented in the springs and with higher levels of238 U, suggesting its high tolerance to this particular radionuclide. This diatom species may therefore represent a bio-indicator of high natural levels of uranium., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
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116. New and poorly known "araphid" diatom species (Bacillariophyta) from regions near Lake Titicaca, South America and a discussion on the continued use of morphological characters in "araphid" diatom taxonomy.
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Morales EA, Wetzel CE, and Ector L
- Abstract
Based on two Andean Altiplano samples and on light and scanning electron microscopy analyses, we present six new species of "araphid" diatoms in the genus Pseudostaurosira , P.aedes sp. nov. , P.frankenae sp. nov. , P.heteropolaris sp. nov. , P.oblonga sp. nov. , P.occulta sp. nov. , and P.pulchra sp. nov. Additional data are provided for four other known taxa, Nanofrustulumcataractarum , N.rarissimum , P.sajamaensis and P.vulpina , the latter species corresponding to a stat. nov. based on a variety of P.laucensis . Each taxon is described morphologically and compared with closely related published taxa, using characters such as axial area, virgae, vimines, areolar shape, volae, internal striae depositions, spines, flaps and apical pore fields, which are not usually used for species distinction within the genus. It is our intention that the detailed morphological descriptions of each taxon and the elaborate comparative tables we provide serve as a basis for correction of neo and paleo-databases for the Altiplano to produce a better account of autecological data and ecological change in the region. Some arguments for our continued use of a morphologically based approach are given in the context of rapid environmental degradation in the Andes and the difficulties in applying molecular approaches in countries such as Bolivia., (Eduardo A. Morales, Carlos E. Wetzel, Luc Ector.)
- Published
- 2021
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117. Extinction of austral diatoms in response to large-scale climate dynamics in Antarctica.
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Pinseel E, Van de Vijver B, Wolfe AP, Harper M, Antoniades D, Ashworth AC, Ector L, Lewis AR, Perren B, Hodgson DA, Sabbe K, Verleyen E, and Vyverman W
- Abstract
Despite evidence for microbial endemism, an understanding of the impact of geological and paleoclimate events on the evolution of regional protist communities remains elusive. Here, we provide insights into the biogeographical history of Antarctic freshwater diatoms, using lacustrine fossils from mid-Miocene and Quaternary Antarctica, and dovetail this dataset with a global inventory of modern freshwater diatom communities. We reveal the existence of a diverse mid-Miocene diatom flora bearing similarities with several former Gondwanan landmasses. Miocene cooling and Plio-Pleistocene glaciations triggered multiple extinction waves, resulting in the selective depauperation of this flora. Although extinction dominated, in situ speciation and new colonizations ultimately shaped the species-poor, yet highly adapted and largely endemic, modern Antarctic diatom flora. Our results provide a more holistic view on the scale of biodiversity turnover in Neogene and Pleistocene Antarctica than the fragmentary perspective offered by macrofossils and underscore the sensitivity of lacustrine microbiota to large-scale climate perturbations.
- Published
- 2021
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118. Diversity, ecology and distribution of benthic diatoms in thermo-mineral springs in Auvergne (France) and Sardinia (Italy).
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Lai GG, Beauger A, Wetzel CE, Padedda BM, Voldoire O, Lugliè A, Allain E, and Ector L
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This study investigated and compared the diatom flora from thermo-mineral springs in Auvergne (France) and Sardinia (Italy). Samples were collected from rock/cobbles and fine sediments in 16 springs between January 2015 and March 2017. A total of 207 taxa (59 genera) were found. Multivariate analyses revealed significant differences in species composition and abundance among diatom assemblages both within each geographic region and between Auvergne and Sardinia (global R = 0.516; p = 0.002), suggesting the importance of local and climatic factors in species distribution. Based on abundance and common occurrence in multiple sites, some taxa can be considered more representative of springs in each region: Crenotia thermalis for Auvergne and Lemnicola exigua , Nitzschia amphibia , N. inconspicua and Rhopalodia operculata for Sardinia. pH, conductivity and HCO
3 - were the most significant environmental variables for diatom assemblages. Our results highlight the high heterogeneity of these spring systems. Future taxonomic insights can be useful to define the identity of some abundant and dominant taxa not identified at the species level in this study. Their identification is a crucial step for a more precise ecological characterization and comparison of these peculiar spring systems., Competing Interests: The authors declare there are no competing interests.- Published
- 2019
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119. Unexpected consequences of bombing. Community level response of epiphytic diatoms to environmental stress in a saline bomb crater pond area.
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Földi A, Ács É, Grigorszky I, Ector L, Wetzel CE, Várbíró G, Kiss KT, Dobosy P, Trábert Z, Borsodi AK, and Duleba M
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- Bombs, Diatoms chemistry, Ecosystem, Environmental Monitoring, Hungary, Nitrogen chemistry, Phylogeny, Ponds chemistry, Salinity, Wetlands, World War II, Diatoms growth & development, Ecology, Ponds analysis, Water Quality
- Abstract
The spatial response of epiphytic diatom communities to environmental stress was studied in a moderately saline wetland area located in the plain of Danube-Tisza Interfluve, Hungary. The area is characterised by World War II bomb crater ponds and can be regarded as an excellent ecological model system where the dispersion of species is slightly limited by distance. To study the effect of environmental variables on the communities, canonical correspondence analysis was applied. Salinity, pH, total suspended solids, total phosphorous and depth proved to be significant environmental drivers in this analysis. The ecological status of the ponds was assessed with Ziemann's halobity index, as the trophity-depending metric cannot be applied to these habitats (due to the naturally high phosphorus content). Ponds in "good" ecological status significantly differed from those appertaining to water quality category of "not-good" ecological status considering characteristic of natural astatic soda pans (e.g. salinity, pH, ammonium, total phosphorous concentration, nitrogen:phosphorous ratio and turbidity). The differences between epiphytic diatom communities inhabiting the ponds were detected using non-parametric multidimensional scaling. The samples formed three groups according to the types of ponds ("transparent", "transitional" and "turbid") based on the width of the macrophyte belt around them. Indicator species related to the ecological status of the ponds and diatom communities contributing to the separation of groups of ponds were identified. One of the indicator species differed from species already described. Light and scanning electron microscopy features and phylogenetic analyses based on three genes (18S and 28S rRNA genes, rbcL) proved that it was a new species of Nitzschia genus, closely related to Nitzschia frustulum and Nitzschia inconspicua. Therefore, description of a new species, Nitzschia reskoi Ács, Duleba, C.E.Wetzel & Ector is proposed. We concluded that the increasing abundance of Nitzschia reskoi was a signal of the degradation of the intermittent saline wetlands., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2018
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120. DNA metabarcoding and microscopic analyses of sea turtles biofilms: Complementary to understand turtle behavior.
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Rivera SF, Vasselon V, Ballorain K, Carpentier A, Wetzel CE, Ector L, Bouchez A, and Rimet F
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- Animals, Behavior, Animal, Comoros, Indian Ocean Islands, Microscopy, Phylogeny, Biofilms, DNA Barcoding, Taxonomic, Metagenome, Metagenomics methods, Turtles microbiology
- Abstract
Sea turtles are distributed in tropical and subtropical seas worldwide. They play several ecological roles and are considered important indicators of the health of marine ecosystems. Studying epibiotic diatoms living on turtle shells suggestively has great potential in the study of turtle behavior because diatoms are always there. However, diatom identification at the species level is time consuming, requires well-trained specialists, and there is a high probability of finding new taxa growing on turtle shells, which makes identification tricky. An alternative approach based on DNA barcoding and high throughput sequencing (HTS), metabarcoding, has been developed in recent years to identify species at the community level by using a DNA reference library. The suitabilities of morphological and molecular approaches were compared. Diatom assemblages were sampled from seven juvenile green turtles (Chelonia mydas) from Mayotte Island, France. The structures of the epibiotic diatom assemblages differed between both approaches. This resulted in different clustering of the turtles based on their diatom communities. Metabarcoding allowed better discrimination between turtles based on their epibiotic diatom assemblages and put into evidence the presence of a cryptic diatom diversity. Microscopy, for its part, provided more ecological information of sea turtles based on historical bibliographical data and the abundances of ecological guilds of the diatom species present in the samples. This study shows the complementary nature of these two methods for studying turtle behavior.
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- 2018
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121. Development of the Trophic Water Quality Index (TWQI) for subtropical temperate Brazilian lotic systems.
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Lobo EA, Schuch M, Heinrich CG, da Costa AB, Düpont A, Wetzel CE, and Ector L
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- Brazil, Diatoms classification, Environmental Monitoring methods, Multivariate Analysis, Rivers, Eutrophication, Water Pollution statistics & numerical data, Water Quality standards
- Abstract
This research aimed at developing the Trophic Water Quality Index (TWQI) for subtropical temperate Brazilian lotic systems based on a review of the indicative values of diatom species obtained using multivariate analysis techniques and considering the environmental gradient defined by a series of measured physical, chemical, and microbiological variables. Sampling was conducted from 2005 to 2009 in the Pardo River Hydrographic Basin, Rio Grande do Sul (RS), Brazil, and in the Andreas Stream Hydrographic Basin, RS, from 2012 to 2013. A total of 140 biological samples and 211 abiotic samples were collected. Data were analyzed by cluster analysis based on the Ward method and canonical correspondence analysis (CCA). The results indicated that total phosphate, turbidity, ammonia nitrogen, electrical conductivity, dissolved oxygen, and thermotolerant coliforms showed a significant correlation with the sample ordination made by CCA, in relation to a gradient of eutrophication. Eutrophication was operationally defined in a broad sense, including the problem of organic pollution and eutrophication of the water. The determination of the different tolerance degrees to eutrophication of the diatom taxa was used to assign trophic values of 1, 2.5, and 4 to species, corresponding to levels of low, medium, and high tolerance, respectively. By using the trophic values obtained for each diatom species, the TWQI constituted a new technological tool for environmental monitoring studies and showed a consistent, robust, and objective database for water quality assessment in subtropical temperate Brazilian lotic systems.
- Published
- 2015
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122. Influence of thermal regime and land use on benthic invertebrate communities inhabiting headwater streams exposed to contrasted shading.
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Dohet A, Hlúbiková D, Wetzel CE, L'Hoste L, Iffly JF, Hoffmann L, and Ector L
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- Animals, Climate Change, Ecosystem, Environmental Monitoring, Invertebrates physiology, Rivers chemistry, Temperature
- Abstract
Headwaters account for a high proportion of total freshwater stream-channel length in a drainage basin and are critical habitats for rare, endangered, and specialized species. In the context of climate warming, increasing water temperatures may be an ultimate threat to cold-adapted species even in temperate ecosystems. Climate change effects on streams may interact with other pressures such as pollution or habitat fragmentation, confounding their real impact on biological communities. Three headwater streams exposed to contrasted shading and land use conditions were sampled over a three-year period in spring and autumn (2010-2012). Five stations distributed along the longitudinal continuum were chosen in the upstream part of each stream. In addition to benthic invertebrate sampling, water temperature was recorded continuously using data loggers. Results showed that the riparian woodland associated with forested land use throughout the catchment clearly moderated winter temperature minima, summer temperature maxima and thermal variability compared to open river channels with narrow or absent riparian tree cover. Although, the variability in macroinvertebrate species distribution was mainly attributed to anthropogenic land use in the catchment, a significant part of the variability was explained by temperature descriptors such as the number of cumulative degree-days in summer and extremes in winter temperature. Trichoptera species preferring headwaters and cold water temperatures were found exclusively in the forested unimpacted stream. Conservation issues are discussed in relation to the predicted loss of the potential future distributions of these Trichoptera cold-adapted species., (Copyright © 2014 Elsevier B.V. All rights reserved.)
- Published
- 2015
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123. Biogeography and phylogenetic position of a warm-stenotherm centric diatom, Skeletonema potamos (C.I. Weber) hasle and its long-term dynamics in the River Danube.
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Duleba M, Ector L, Horváth Z, Kiss KT, Molnár LF, Pohner Z, Szilágyi Z, Tóth B, Vad CF, Várbíró G, and Acs É
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- Cluster Analysis, DNA, Algal chemistry, DNA, Algal genetics, DNA, Chloroplast, DNA, Ribosomal chemistry, DNA, Ribosomal genetics, Diatoms genetics, Europe, Molecular Sequence Data, RNA, Ribosomal genetics, RNA, Ribosomal, 18S genetics, Seasons, Sequence Analysis, DNA, Temperature, Diatoms classification, Diatoms isolation & purification, Phylogeography, Rivers parasitology
- Abstract
Skeletonema potamos is a poorly known freshwater species in the ancestrally and predominantly marine genus Skeletonema. With phylogenetic analysis of two nuclear {partial SSU (18S) and partial LSU (28S) rDNA)} and two chloroplast (rbcL and psbC) genes, we verified its placement within the genus Skeletonema and identified the mostly brackish species, Skeletonema subsalsum, as its closest known relative. Comparisons of SSU and LSU rRNA genes from S. potamos populations from Europe and North America revealed no intraspecific variation. Skeletonema potamos can be a dominant element of the phytoplankton community in various ecosystems, including the River Danube. We tracked phytoplankton composition in the River Danube weekly from 1979 to 2 012, and throughout this period, S. potamos exhibited a strong increase in proportion of total phytoplankton abundance and biomass - an increase that was correlated with increasing water temperature over the same time period. Current records indicate a temperate distribution of S. potamos, but ecological data predict possible expansion of its geographic range and increase in seasonal duration within existing habitats in response to the warming of surface waters., (Copyright © 2014 Elsevier GmbH. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
124. Effect of riparian vegetation on diatom assemblages in headwater streams under different land uses.
- Author
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Hlúbiková D, Novais MH, Dohet A, Hoffmann L, and Ector L
- Subjects
- Diatoms growth & development, Ecosystem, Environment, Trees, Urbanization, Diatoms classification, Environmental Monitoring methods, Rivers chemistry
- Abstract
Differences in the structure of diatom assemblages in headwaters with contrasting shading conditions and different land use in the buffer zone and upper catchment were studied in order to evaluate the influence of the lack of riparian vegetation on the biofilm. The objective was to ascertain whether a riparian buffer can mitigate the negative influence of human induced disturbance and pollution on diatom assemblages in headwaters. Four streams were selected in order to maximize the differences in the land cover and minimize other environmental gradients. Multivariate statistics, different comparative and permutation tests and correlations were applied to compare the diatom assemblages, the Specific Polluosensitivity Index (IPS) and the diatom ecological guilds (low profile, high profile and motile) among the sites studied and to evaluate their responses to disturbances. The analysis showed that low profile diatoms typically dominated in forested headwaters with limited resources, whilst assemblages at impacted sites showed a wider range of growth forms. In unimpacted streams, the diatom assemblages were influenced by temperature, pH, conductivity and calcium, as usually reported for oligotrophic streams with high natural disturbance due to fast current and shading. In both shaded and unshaded impacted streams, the importance of nutrients and land use disturbance, especially urbanization, prevailed. This trend was also reflected by the IPS index that showed consistently lower values at impacted sites, correlating most significantly with nutrients. The diatom species composition as well as diatom guilds at impacted sites were similar, regardless of the presence or absence of riparian vegetation, and were significantly influenced by seasonal changes. Our results indicate that diatoms react sensitively to alterations of the water environment in headwaters, induced by anthropogenic activities, and these impacts are not buffered by an intact riparian zone. Diatoms closely reflected land use practices in the upper catchment regardless of the buffer zone status., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
125. Distance decay of similarity in neotropical diatom communities.
- Author
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Wetzel CE, Bicudo Dde C, Ector L, Lobo EA, Soininen J, Landeiro VL, and Bini LM
- Subjects
- Brazil, Geography, Phytoplankton growth & development, Rivers, Biota, Diatoms growth & development, Tropical Climate
- Abstract
Background: The regression of similarity against distance unites several ecological phenomena, and thus provides a highly useful approach for illustrating the spatial turnover across sites. Our aim was to test whether the rates of decay in community similarity differ between diatom growth forms suggested to show different dispersal ability. We hypothesized that the diatom group with lower dispersal ability (i.e. periphyton) would show higher distance decay rates than a group with higher dispersal ability (i.e. plankton)., Methods/principal Findings: Periphyton and phytoplankton samples were gathered at sites distributed over an area of approximately 800 km length in the Negro River, Amazon basin, Brazil, South America (3°08'00"S; 59°54'30"W). Distance decay relationships were then estimated using distance-based regressions, and the coefficients of these regressions were compared among the groups with different dispersal abilities to assess our predictions. We found evidence that different tributaries and reaches of the Negro River harbor different diatom communities. As expected, the rates of distance decay in community similarity were higher for periphyton than for phytoplankton indicating the lower dispersal ability of periphytic taxa., Conclusions/significance: Our study demonstrates that the comparison of distance decay relationships among taxa with similar ecological requirements, but with different growth form and thus dispersal ability provides a sound approach to evaluate the effects of dispersal ability on beta diversity patterns. Our results are also in line with the growing body of evidence indicating that microorganisms exhibit biogeographic patterns. Finally, we underscore that clumbing all microbial taxa into one group may be a flawed approach to test whether microbes exhibit biogeographic patterns.
- Published
- 2012
- Full Text
- View/download PDF
126. NITZSCHIA ALICAE SP. NOV. AND N. PURIFORMIS SP. NOV., NEW DIATOMS FROM EUROPEAN RIVERS AND COMPARISON WITH THE TYPE MATERIAL OF N. SUBLINEARIS AND N. PURA(1).
- Author
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Hlúbiková D, Blanco S, Falasco E, Gomà J, Hoffmann L, and Ector L
- Abstract
Nitzschia sublinearis Hustedt and N. pura Hustedt are common oligosaprobic freshwater diatom species that frequently occur in diatom inventories, thus being important in water quality studies. Both are considered as species with overlapping diagnostic criteria in several floras, which is typical of the whole genus Nitzschia. The type material of Hustedt of N. sublinearis and N. pura was examined using LM and EM in order to document the range of variation within the type populations and to compare it with populations occurring in different European rivers. Detailed observations allowed recognition of two new freshwater diatom species: N. alicae sp. nov., occurring in mesotrophic up to eutrophic conditions, and N. puriformis sp. nov., mostly occurring in oligotrophic habitats, both in rivers and streams at middle and high altitudes. The most reliable taxonomic features that separate both new species from the most similar taxa are the density of fibulae and striae, valve shape, and valve width as well as the shape of areolae. Morphological examination of different populations indicates that N. puriformis is relatively common in European rivers and has been overlooked to date and confounded with N. pura by several researchers. By contrast, N. alicae has, to date, been collected only in Slovakia and Northern Italy, but with a high frequency of occurrence and sometimes in high abundance at sites., (© 2009 Phycological Society of America.)
- Published
- 2009
- Full Text
- View/download PDF
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