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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 2019 Publication Revue Abrégée Water Res.
Volume 163 Numéro Pages (down) 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 Gharbia, H.; Laabir, M.; Ben Mhamed, A.; Gueroun, S.K.M.; Yahia, M.N.D.; Nouri, H.; M'Rabet, C.; Shili, A.; Yahia, O.K.-D.
Titre Occurrence of epibenthic dinoflagellates in relation to biotic substrates and to environmental factors in Southern Mediterranean (Bizerte Bay and Lagoon, Tunisia): An emphasis on the harmful Ostreopsis spp., Prorocentrum lima and Coolia monotis Type Article scientifique
Année 2019 Publication Revue Abrégée Harmful Algae
Volume 90 Numéro Pages (down) 101704
Mots-Clés algal blooms; allelopathic interactions; cf. ovata blooms; coastal waters; Environmental factors; Epibenthic dinoflagellates; genus ostreopsis; Macrophytes; posidonia-oceanica; recently-deposited sediment; seasonal-changes; ships ballast water; Southern Mediterranean; toxin production
Résumé Harmful events associated with epibenthic dinoflagellates, have been reported more frequently over the last decades. Occurrence of potentially toxic benthic dinoflagellates, on the leaves of two magnoliophytes (Cymodocea nodosa and Zostera noltei) and thalli of the macroalgae (Ulva rigida), was monitored over one year (From May 2015 to April 2016) in the Bizerte Bay and Lagoon (North of Tunisia, Southern Mediterranean Sea). The investigated lagoon is known to be highly anthropized. This is the first report on the seasonal distribution of epibenthic dinoflagellates hosted by natural substrates, from two contrasted, adjacent coastal Mediterranean ecosystems. The environmental factors promoting the development of the harmful epibenthic dinoflagellates Ostreopsis spp., Prorocentrum lima and Coolia monotis were investigated. The highest cell densities were reached by Ostreopsis spp. (1.9 x 10(3) cells g(-1) FW, in October 2015), P. lima (1.6 x 10(3) cells g(-1) FW, in June 2015) and C. monotis (1.1 x 10(3) cells g(-1) FW, in May 2015). C. nodosa and Z. noltei were the most favorable host macrophytes for C. monotis (in station L2) and Ostreopsis spp. (in station L3), respectively. Positive correlations were recorded between Ostreopsis spp. and temperature. Densities of the epibenthic dinoflagellates varied according to the collection site, and a great disparity was observed between the Bay and the Lagoon. Maximum concentrations were recorded on C. nodosa leaves from the Bizerte Bay, while low epiphytic cell abundances were associated with macrophytes sampled from the Bizerte Lagoon. The observed differences in dinoflagellate abundances between the two ecosystems (Bay-Lagoon) seemed not related to the nutrients, but rather to the poor environmental conditions in the lagoon.
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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:000502893700004 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2695
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Auteur Minguez, L.; Pedelucq, J.; Farcy, E.; Ballandonne, C.; Budzinski, H.; Halm-Lemeille, M.-P.
Titre Toxicities of 48 pharmaceuticals and their freshwater and marine environmental assessment in northwestern France Type Article scientifique
Année 2016 Publication Revue Abrégée Environ. Sci. Pollut. Res.
Volume 23 Numéro 6 Pages (down) 4992-5001
Mots-Clés antibiotics; Aquatic environment; aquatic environment; Ecotoxicity; emerging contaminants; Fate; mec; pec; Pharmaceuticals; prioritization; risk; risk-assessment; sensitivity; surface waters
Résumé A risk assessment for freshwater and marine ecosystems is presented for 48 pharmaceutical compounds, belonging to 16 therapeutic classes, and prescribed in northwestern France. Ecotoxicity data were obtained on two freshwater organisms, i.e., crustacean Daphnia magna and the green algae Pseudokirchneriella subcapitata, and on two marine organisms, i.e., the crustacean Artemia salina and the diatom Skeletonema marinoi. Measured environmental concentrations (MEC), in the Orne River and sea off Merville-Franceville in the Basse-Normandie region, were compared to the predicted environmental concentrations (PEC). Predicted no-effect concentrations (PNEC) were derived from acute data for each compound. Then, a risk assessment for each compound and the mixture was performed by calculating risk quotients (RQ as PEC or MEC/PNEC ratio). Results showed that no immediate acute toxicities were expected even if some compounds displayed strong toxicities at very low concentrations. Antibiotics, antidepressants, and antifungals would deserve attention because of their high or median ecological risk suspected on marine and freshwater ecosystems. Marine ecosystems would be more sensitive to pharmaceutical residues.
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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 0944-1344 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2064
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Auteur Galand, P.E.; Pereira, O.; Hochart, C.; Auguet, J-C.; Debroas, D.
Titre A strong link between marine microbial community composition and function challenges the idea of functional redundancy Type Article scientifique
Année 2018 Publication Revue Abrégée Isme J.
Volume 12 Numéro 10 Pages (down) 2470-2478
Mots-Clés biosphere; cell; depth; diversity; dynamics; gene; program; sequencing data; short read alignment; waters
Résumé Marine microbes have tremendous diversity, but a fundamental question remains unanswered: why are there so many microbial species in the sea? The idea of functional redundancy for microbial communities has long been assumed, so that the high level of richness is often explained by the presence of different taxa that are able to conduct the exact same set of metabolic processes and that can readily replace each other. Here, we refute the hypothesis of functional redundancy for marine microbial communities by showing that a shift in the community composition altered the overall functional attributes of communities across different temporal and spatial scales. Our metagenomic monitoring of a coastal northwestern Mediterranean site also revealed that diverse microbial communities harbor a high diversity of potential proteins. Working with all information given by the metagenomes (all reads) rather than relying only on known genes (annotated orthologous genes) was essential for revealing the similarity between taxonomic and functional community compositions. Our finding does not exclude the possibility for a partial redundancy where organisms that share some specific function can coexist when they differ in other ecological requirements. It demonstrates, however, that marine microbial diversity reflects a tremendous diversity of microbial metabolism and highlights the genetic potential yet to be discovered in an ocean of microbes.
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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 1751-7362 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2435
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Auteur Boukef, I.; El Bour, M.; Al Gallas, N.; El Bahri, O.; Mejri, S.; Mraouna, R.; Ben Aissa, R.; Boudabous, A.; Got, P.; Troussellier, M.
Titre Survival of Escherichia coli Strains in Mediterranean Brackish Water in the Bizerte Lagoon in Northern Tunisia Type Article scientifique
Année 2010 Publication Revue Abrégée Water Environ Res
Volume 82 Numéro 11 Pages (down) 2249-2257
Mots-Clés bizerte lagoon; brackish water; coastal waters; cytotoxicity; enteric bacteria; escherichia coli; fecal-coliforms; marine waters; salmonella-typhimurium; seawater microcosms; sewage; shigella-dysenteriae type-1; sunlight; survival; viability; virulence
Résumé This study investigated survival and virulence of Escherichia coli strains exposed to natural conditions in brackish water. Two E. coli strains (O126:B16 and O55:B5) were incubated in water microcosms in the Bizerte lagoon in Northern Tunisia and exposed for 12 days to natural sunlight in June (231 to 386 W/m(2), 26 +/- 1 degrees C, 30 g/L) and in April (227 to 330 W/m(2), 17 +/- 1 degrees C, 27 g/L) or maintained in darkness for 21 days (17 +/- 1 degrees C, 27 g/L). The results revealed that sunlight was the most significant inactivating factor (decrease of 3 Ulog within 48 hours for the two strains) compared to salinity and temperature (in darkness). Survival time of the strains was prolonged as they were maintained in darkness. Local strain (E. coli O55:B5) showed better survival capacity (T(90) = 52 hours) than E. coli O126:B16 (T(90) = 11 h). For both, modifications were noted only for some metabolic activities of carbohydrates hydrolysis. Cytotoxicity of the two strains, tested on Vero cell, was maintained during the period of survival. Water Environ. Res., 82, 2249 (2010).
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1061-4303 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 864
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