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Auteur Bouvy, M.; Combe, M.; Bettarel, Y.; Dupuy, C.; Rochelle-Newall, E.; Charpy, L.
Titre Uncoupled viral and bacterial distributions in coral reef waters of Tuamotu Archipelago (French Polynesia) Type Article scientifique
Année 2012 Publication Revue Abrégée Marine Pollution Bulletin
Volume 65 Numéro 10–12 Pages 506-515
Mots-Clés Coral reef waters; Distributions; Strategy lifes; Virus; bacteria
Résumé This study examined the distribution of virioplankton and bacterioplankton in two coral reef systems (Ahe and Takaroa atolls) in the Tuamotu Archipelago, in comparison with the surrounding oligotrophic ocean. Mean concentrations of 4.8 × 105 and 6.2 × 105 cells ml−1 for bacteria and 8.1 × 106 and 4.3 × 106 VLP (virus-like particle) ml−1 were recorded in Ahe and Takaroa lagoons, respectively. Chlorophyll-a concentrations and dissolved organic matter were higher in Ahe whereas 3H thymidine incorporation rates were higher in Takaroa. First data on lytic and lysogenic strategies of phages in coral reef environments were discussed in this paper. The fraction of visibly infected cells by viruses was negligible regardless of the lagoon station (mean = 0.15%). However, the fraction of lysogenic cells ranged between 2.5% and 88.9%. Our results suggest that the distribution patterns of virioplankton are apparently not coupled to the spatial dynamics of the bacterioplankton communities.
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ISSN (up) 0025-326x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 923
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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 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
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ISSN (up) 0043-1354 ISBN Médium
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Notes WOS:000483006400038 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2636
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Auteur Meddeb, M.; Grami, B.; Chaalali, A.; Haraldsson, M.; Niquil, N.; Pringault, O.; Sakka Hlaili, A.
Titre Plankton food-web functioning in anthropogenically impacted coastal waters (SW Mediterranean Sea): an ecological network analysis Type Article scientifique
Année 2018 Publication Revue Abrégée Progress in Oceanography
Volume Numéro Pages
Mots-Clés Ecological Network Analysis; Food-web modelling; Mediterranean coastal waters; plankton ecology
Résumé The study is the first attempt to (i) model spring food webs in three SW Mediterranean ecosystems which are under different anthropogenic pressures and (ii) to project the consequence of this stress on their function. Linear inverse models were built using the Monte Carlo method coupled with Markov Chains to characterize the food-web status of the Lagoon, the Channel (inshore waters under high eutrophication and chemical contamination) and the Bay of Bizerte (offshore waters under less anthropogenic pressure). Ecological network analysis was used for the description of structural and functional properties of each food web and for inter-ecosystem comparisons. Our results showed that more carbon was produced by phytoplankton in the inshore waters (966–1234 mg C m-2 d-1) compared to the Bay (727 mg C m-2 d-1). The total ecosystem carbon inputs into the three food webs was supported by high primary production, which was mainly due to >10µm algae. However, the three carbon pathways were characterized by low detritivory and a high herbivory which was mainly assigned to protozooplankton. This latter was efficient in channelling biogenic carbon. In the Lagoon and the Channel, foods webs acted almost as a multivorous structure with a tendency towards herbivorous one, whereas in the Bay the herbivorous pathway was more dominant. Ecological indices revealed that the Lagoon and the Channel food webs/systems had high total system throughput and thus were more active than the Bay. The Bay food web, which had a high relative ascendency value, was more organized and specialized. This inter–ecosystem difference could be due to the varying levels of anthropogenic impact among sites. Indeed, the low value of Finn’s cycling index indicated that the three systems are disturbed, but the Lagoon and the Channel, with low average path lengths, appeared to be more stressed, as both sites have undergone higher chemical pollution and nutrient loading. This study shows that ecosystem models combined with ecological indices provide a powerful approach to detect change in environmental status and anthropogenic impacts.
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ISSN (up) 0079-6611 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2292
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Auteur Alves-Junior, F. de A.; Bertrand, A.; Camara de Araujo, M. de A.L.; de Carvalho Paiva, R.J.; de Souza-Filho, J.F.
Titre First Report of the Ectoparasitic Isopod, Holophryxus acanthephyrae Stephensen 1912 (Cymothoida: Dajidae) in the South Atlantic: Recovered from a New Host, the Deep-Sea Shrimp, Acanthephyra acanthitelsonis Spence Bate, 1888 Type Article scientifique
Année 2019 Publication Revue Abrégée Thalassas
Volume 35 Numéro 1 Pages 13-15
Mots-Clés Brazilian waters; Deep-sea shrimp; epicaridea; genus; Isopods; Parasitism; Rocas Atoll
Résumé The crustacean family of isopods, Dajidae, comprises 18 genera containing 54 species with widespread distribution. The species of this family are ectoparasites, especially on euphausiids, mysids and shrimps. The species of Holophryxus acanthephyrae has a life cycle involving a first intermediate host (copepod) and a definitive host (shrimp), and adheres particularly on deep-sea shrimps of genus Acanthephyra. Here, we make the first report of dajid isopod Holophryxus acanthephyrae from Brazilian waters (South Atlantic) and the first occurrence as parasite on deep-sea shrimp Acanthephyra acanthitelsonis. The specimen was collected under the framework of the project ABRACOS 2 (Acoustic along the BRazilian COast), on board of R/V Antea in April 2017, using a Micronekton net (mesh size of 10mm) in Rocas Atoll. The specimen female of Holophryxus acanthephyrae was found in pelagic zone in Rocas Atoll, at 630m depth. This study increases the knowledge on Dajidae family and their host range.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN (up) 0212-5919 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2581
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Auteur Boukef, I.; Bejaoui, B.; Hassan, M.B.; Mraouna, R.; Got, P.; Harzallah, A.; Elbour, M.
Titre Spatial distribution and decay rates of coliforms in the sediments and water column of the bizerte lagoon Type Article scientifique
Année 2012 Publication Revue Abrégée Vie Milieu
Volume 62 Numéro 1 Pages 29-36
Mots-Clés bizerte lagoon; coastal waters; contamination; environmental-conditions; escherichia coli decay; estuarine; fecal indicator bacteria; pathogenic bacteria; pollution; recreational waters; seasonal survey; seawater; sunlight; sunlight inactivation; total coliform
Résumé In order to assess the impact of bacterial input loads in Bizerte lagoon (Northern Tunisia), a seasonal survey was done for total coliform bacteria covering the whole lagoon area, to reproduce and prevent dispersion of input loads of terrestrial discharges in the lagoon. Effect of solar radiation on Escherichia coli strains was investigated using seawater microcosms comparatively exposed to sunlight and dark conditions. The results revealed (i) high charges of coliforms in the sediment rather than in the water column, (ii) total coliforms increased periodically with season in both compartments, (iii) anthropogenic discharges influence coastal areas of the lagoon, and (iv) solar radiation has an effect on decay rate of E. coli maintained in microcosm experiments.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN (up) 0240-8759 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 846
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