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Auteur Olokotum, M.; Mitroi, V.; Troussellier, M.; Semyalo, R.; Bernard, C.; Montuelle, B.; Okello, W.; Quiblier, C.; Humbert, J.-F.
Titre A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Harmful Algae
Volume 96 Numéro Pages 101829
Mots-Clés climate-change; Consequences of cyanobacterial blooms; Cyanobacteria; East Africa; Eutrophication; harmful algal blooms; introduced nile perch; Lake Victoria; land-use; lates-niloticus; microcystin concentrations; murchison bay; nutrient concentrations; nyanza gulf; oreochromis-niloticus; Potential toxicity; Socioecological analysis
Résumé Africa is experiencing high annual population growth in its major river basins. This growth has resulted in significant land use change and pollution pressures on the freshwater ecosystems. Among them, the Lake Victoria basin, with more than 42 million people, is a unique and vital resource that provides food and drinking water in East Africa. However, Lake Victoria (LV) has experienced a progressive eutrophication and substantial changes in the fish community leading to recurrent proliferation of water hyacinth and cyanobacteria. Based on an extensive literature review, we show that cyanobacterial biomasses and microcystin concentrations are higher in the bays and gulfs (B&Gs) than in the open lake (OL), with Microcystis and Dolichospermum as the dominant genera. These differences between the B&Gs and the OL are due to differences in their hydrological conditions and in the origins, type and quantities of nutrients. Using data from the literature, we describe the multiple ways in which the human population growth in the LV watershed is connected to the increasing occurrence of cyanobacterial blooms in the OL and B&Gs. We also described the consequences of cyanobacterial blooms on food resources and fishing and on direct water use and water supply of local populations, with their potential consequences on the human health. Finally, we discuss the actions that have been taken for the protection of LV. Although many projects have been implemented in the past years in order to improve the management of waste waters or to reduce deforestation and erosion, the huge challenge of the reduction of cyanobacterial blooms in LV by the control of eutrophication seems far from being achieved.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1568-9883 ISBN Médium
Région Expédition Conférence
Notes WOS:000541912700007 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2822
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Auteur Escalas, A.; Catherine, A.; Maloufi, S.; Cellamare, M.; Hamlaoui, S.; Yepremian, C.; Louvard, C.; Troussellier, M.; Bernard, C.
Titre Drivers and ecological consequences of dominance in periurban phytoplankton communities using networks approaches Type Article scientifique
Année (down) 2019 Publication Revue Abrégée Water Res.
Volume 163 Numéro Pages Unsp-114893
Mots-Clés blooms; climate-change; Co-occurrence network; Community cohesion; Community functioning; cooccurrence patterns; cyanobacteria dominance; diversity; Dominance; fresh-waters; lakes; light; Periurban waterbodies; Phytoplankton; resource use efficiency; species richness
Résumé Evaluating the causes and consequences of dominance by a limited number of taxa in phytoplankton communities is of huge importance in the current context of increasing anthropogenic pressures on natural ecosystems. This is of particular concern in densely populated urban areas where usages and impacts of human populations on water ecosystems are strongly interconnected. Microbial biodiversity is commonly used as a bioindicator of environmental quality and ecosystem functioning, but there are few studies at the regional scale that integrate the drivers of dominance in phytoplankton communities and their consequences on the structure and functioning of these communities. Here, we studied the causes and consequences of phytoplankton dominance in 50 environmentally contrasted waterbodies, sampled over four summer campaigns in the highly-populated Ile-de-France region (IDF). Phytoplankton dominance was observed in 32-52% of the communities and most cases were attributed to Chlorophyta (35.5-40.6% of cases) and Cyanobacteria (30.3-36.5%). The best predictors of dominance were identified using multinomial logistic regression and included waterbody features (surface, depth and connection to the hydrological network) and water column characteristics (total N, TN:TP ratio, water temperature and stratification). The consequences of dominance were dependent on the identity of the dominant organisms and included modifications of biological attributes (richness, cohesion) and functioning (biomass, RUE) of phytoplankton communities. We constructed co-occurrence networks using high resolution phytoplankton biomass and demonstrated that networks under dominance by Chlorophyta and Cyanobacteria exhibited significantly different structure compared with networks without dominance. Furthermore, dominance by Cyanobacteria was associated with more profound network modifications (e.g. cohesion, size, density, efficiency and proportion of negative links), suggesting a stronger disruption of the structure and functioning of phytoplankton communities in the conditions in which this group dominates. Finally, we provide a synthesis on the relationships between environmental drivers, dominance status, community attributes and network structure. (C) 2019 Elsevier Ltd. All rights reserved.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0043-1354 ISBN Médium
Région Expédition Conférence
Notes WOS:000483006400038 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2636
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Auteur Ben Ouada, S.; Ben Ali, R.; Cimetiere, N.; Leboulanger, C.; Ben Ouada, H.; Sayadi, S.
Titre Biodegradation of diclofenac by two green microalgae: Picocystis sp. and Graesiella sp Type Article scientifique
Année (down) 2019 Publication Revue Abrégée Ecotox. Environ. Safe.
Volume 186 Numéro Pages Unsp-109769
Mots-Clés algae; Biodegradation; Biotransformation; bisphenol-a; contaminants; cyanobacteria; Diclofenac; Extremophiles; light-intensity; Microalgae; pharmaceuticals diclofenac; removal; Removal; temperature; transformation products
Résumé The aim of the present study was to provide an integrated view of algal removal of diclofenac (DCF). Two isolated microalgal strains Picocystis sp. and Graesiella sp. were cultivated under different DCF concentrations and their growth, photosynthetic activity and diclofenac removal efficiency were monitored. Results showed that DCF had slight inhibitory effects on the microalgal growth which did not exceed 21% for Picocystis and 36% for Graesiella after 5 days. Both species showed different patterns in terms of removal efficiency. In presence of Picocystis sp., the amounts of removed DCF were up to 73%, 43% and 25% of 25, 50 and 100 mg L-1 respectively; whereas only 52%, 28% and 24% were removed in the presence of Graesiella at same DCF tested concentrations. DCF removal was insured mainly by biodegradation. To better reveal the mechanism involved, metabolites analyses were performed. Two DCF biodegradation/biotransformation products were detected in presence of Picocystis. This study indicated that Picocystis performed a satisfactory growth capacity and DCF removal efficiency and thus could be used for treatment of DCF contaminated aqueous systems.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0147-6513 ISBN Médium
Région Expédition Conférence
Notes WOS:000496901100040 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2657
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Auteur Bernard, C.; Escalas, A.; Villeriot, N.; Agogué, H.; Hugoni, M.; Duval, C.; Carré, C.; Got, P.; Sarazin, G.; Jézéquel, D.; Leboulanger, C.; Grossi, V.; Ader, M.; Troussellier, M.
Titre Very Low Phytoplankton Diversity in a Tropical Saline-Alkaline Lake, with Co-dominance of Arthrospira fusiformis (Cyanobacteria) and Picocystis salinarum (Chlorophyta) Type Article scientifique
Année (down) 2019 Publication Revue Abrégée Microb Ecol
Volume 78 Numéro 3 Pages 603-617
Mots-Clés Cyanobacteria; Diversity; Extreme environment; Phytoplankton; Picoeukaryote; Thalassohaline lake
Résumé Lake Dziani Dzaha (Mayotte Island, Indian Ocean) is a tropical thalassohaline lake which geochemical and biological conditions make it a unique aquatic ecosystem considered as a modern analogue of Precambrian environments. In the present study, we focused on the diversity of phytoplanktonic communities, which produce very high and stable biomass (mean2014–2015 = 652 ± 179 μg chlorophyll a L−1). As predicted by classical community ecology paradigms, and as observed in similar environments, a single species is expected to dominate the phytoplanktonic communities. To test this hypothesis, we sampled water column in the deepest part of the lake (18 m) during rainy and dry seasons for two consecutive years. Phytoplanktonic communities were characterized using a combination of metagenomic, microscopy-based and flow cytometry approaches, and we used statistical modeling to identify the environmental factors determining the abundance of dominant organisms. As hypothesized, the overall diversity of the phytoplanktonic communities was very low (15 OTUs), but we observed a co-dominance of two, and not only one, OTUs, viz., Arthrospira fusiformis (Cyanobacteria) and Picocystis salinarum (Chlorophyta). We observed a decrease in the abundance of these co-dominant taxa along the depth profile and identified the adverse environmental factors driving this decline. The functional traits measured on isolated strains of these two taxa (i.e., size, pigment composition, and concentration) are then compared and discussed to explain their capacity to cope with the extreme environmental conditions encountered in the aphotic, anoxic, and sulfidic layers of the water column of Lake Dziani Dzaha.
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Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1432-184x ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2494
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Auteur Duval, C.; Thomazeau, S.; Drelin, Y.; Yepremian, C.; Bouvy, M.; Couloux, A.; Troussellier, M.; Rousseau, F.; Bernard, C.
Titre Phylogeny and salt-tolerance of freshwater Nostocales strains: Contribution to their systematics and evolution Type Article scientifique
Année (down) 2018 Publication Revue Abrégée Harmful Algae
Volume 73 Numéro Pages 58-71
Mots-Clés baltic sea; bloom; comb. nova; Cyanobacteria; dolichospermum; genera anabaena; genetics analysis; great oxidation event; hetR; Morphology; nijH; Nostocaceae; Phylogeny; Physiology; planktonic cyanobacteria; polyphasic approach; Polyphasic approach; Salt-tolerance; toxin production
Résumé Phylogenetic relationships among heterocytous genera (the Nostocales order) have been profoundly modified since the use of polyphasic approaches that include molecular data. There is nonetheless still ample scope for improving phylogenetic delineations of genera with broad ecological distributions, particularly by integrating specimens from specific or up-to-now poorly sampled habitats. In this context, we studied 36 new isolates belonging to Chrysosporum, Dolichospermum, Anabaena, Anabaenopsis, and Cylindrospermopsis from freshwater ecosystems of Burkina-Faso, Senegal, and Mayotte Island. Studying strains from these habitats is of particular interest as we suspected different range of salt variations during underwent periods of drought in small ponds and lakes. Such salt variation may cause different adaptation to salinity. We then undertook a polyphasic approach, combining molecular phylogenies, morphological analyses, and physiological measurements of tolerance to salinity. Molecular phylogenies of 117 Nostocales sequences showed that the 36 studied strains were distributed in seven lineages: Dolichospermum, Chrysosporum, Cylindrospermopsis Raphidiopsis, Anabaenopsis, Anabaena sphaerica var tenuis/Sphaerospermopsis, and two independent Anabaena sphaerica lineages. Physiological data were congruent with molecular results supporting the separation into seven lineages. In an evolutionary context, salinity tolerance can be used as an integrative marker to reinforce the delineation of some cyanobacterial lineages. The history of this physiological trait contributes to a better understanding of processes leading to the divergence of cyanobacteria. In this study, most of the cyanobacterial strains isolated from freshwater environments were salt-tolerant, thus suggesting this trait constituted an ancestral trait of the heterocytous cyanobacteria and that it was probably lost two times secondarily and independently in the ancestor of Dolichospermum and of Cylindrospermopsis. (C) 2018 Elsevier B.V. All rights reserved.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1568-9883 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 2341
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