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Auteur Leruste, A.; Malet, N.; Munaron, D.; Derolez, V.; Hatey, E.; Collos, Y.; De Wit, R.; Bec, B.
Titre (up) First steps of ecological restoration in Mediterranean lagoons: Shifts in phytoplankton communities Type Article scientifique
Année 2016 Publication Revue Abrégée Estuarine, Coastal and Shelf Science
Volume 180 Numéro Pages 190-203
Mots-Clés Coastal lagoons; Nutrient; Phytoplankton; Re-oligotrophication; Sewage effluents
Résumé Along the French Mediterranean coast, a complex of eight lagoons underwent intensive eutrophication over four decades, mainly related to nutrient over-enrichment from continuous sewage discharges. The lagoon complex displayed a wide trophic gradient from mesotrophy to hypertrophy and primary production was dominated by phytoplankton communities. In 2005, the implementation of an 11 km offshore outfall system diverted the treated sewage effluents leading to a drastic reduction of anthropogenic inputs of nitrogen and phosphorus into the lagoons. Time series data have been examined from 2000 to 2013 for physical, chemical and biological (phytoplankton) variables of the water column during the summer period. Since 2006, total nitrogen and phosphorus concentrations as well as chlorophyll biomass strongly decreased revealing an improvement in lagoon water quality. In summertime, the decline in phytoplankton biomass was accompanied by shifts in community structure and composition that could be explained by adopting a functional approach by considering the common functional traits of the main algal groups. These phytoplankton communities were dominated by functional groups of small-sized and fast-growing algae (diatoms, cryptophytes and green algae). The trajectories of summer phytoplankton communities displayed a complex response to changing nutrient loads over time. While diatoms were the major group in 2006 in all the lagoons, the summer phytoplankton composition in hypertrophic lagoons has shifted towards green algae, which are particularly well adapted to summertime conditions. All lagoons showed increasing proportion and occurrence of peridinin-rich dinophytes over time, probably related to their capacity for mixotrophy. The diversity patterns were marked by a strong variability in eutrophic and hypertrophic lagoons whereas phytoplankton community structure reached the highest diversity and stability in mesotrophic lagoons. We observe that during the re-oligotrophication process in coastal lagoons, phytoplankton shows complex trajectories with similarities with those observed in freshwater lake systems.
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ISSN 0272-7714 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1598
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Auteur Melo, D.C.M.; Lira, S.M.A.; Moreira, A.P.B.; Freitas, L.; Lima, C.A.D.; Thompson, F.; Bertrand, A.; Silva, A.C.; Neumann-Leitao, S.
Titre (up) Genetic diversity and connectivity of Flaccisagitta enflata (Chaetognatha: Sagittidae) in the tropical Atlantic ocean (northeastern Brazil) Type Article scientifique
Année 2020 Publication Revue Abrégée PLoS One
Volume 15 Numéro 5 Pages e0231574
Mots-Clés acartia-tonsa; copepod; differentiation; global phylogeography; heterogeneity; marine; mesozooplankton; mitochondrial-dna; pelagic chaetognath; population-structure
Résumé The phylogeography of the holoplanktonic chaetognath Flaccisagitta enflata was investigated in the Tropical Western Atlantic (TWA). Considering the cosmopolitan range of this species and the fact that its entire life cycle is planktonic, the central hypothesis of this study is that F. enflata exhibits connectivity due to its high dispersal capacity, forming a panmictic population among the study sites. The evaluated areas included neritic (Port of Recife-PR, and Tamandare – TA) and oceanic (Fernando de Noronha Archipelago-FN, Rocas Atoll-RA, Guara seamount-GS and Saint Peter and Saint Paul's Archipelago-SPSPA) locations of the Brazilian Blue Amazon. We used COI gene sequences as molecular marker. Partial sequences (425 bp) were obtained for 116 specimens and employed to reconstruct the phylogeny, build an haplotype network, evaluate gene flow through a migration model, and estimate diversity indices, population structuring and demographic history. High levels of haplotype diversity (mean: 0.98) and moderate to high levels of nucleotide diversity (mean: 0.023) were observed. The phylogeny and the haplotype network topologies showed some geographic clustering, indicating local structuring in GS and PR. This finding was supported by the AMOVA high global phi st (0.033, significant) and some pairwise phi st comparisons (7 out of 15 were significantly > 0). Significant differences suggested lower levels of connectivity when GS population was compared to those of FN and SPSPA; as well as when TA was compared to FN. These results might be related to particularities of the oceanic dynamics which rules the TWA, sustaining such dissimilarities. Structuring was also observed between PR and all oceanic locations. We hypothesize that the topography of the port inlet, enclosured by a reef barrier, may constrain the water turnover ratio and thus migration rates of F. enflata in the TWA. Accordingly, Migrate-N yielded a four metapopulations model (PR (sic) TA (sic) SPSPA+FN (sic) GS+RA) as the best (highest probability; similar to 0.90) to represent the structuring of F. enflata in the TWA. Therefore, the null hypothesis of one randomly mating population cannot be accepted. The demographic evaluation demonstrated that the neutral hypothesis of stable populations may not be rejected for most of the locations. This work is the start point to broaden the knowledge on the phylogeography and population genetic structure of a numerically dominant species in the Western Atlantic, with key role in the marine trophic web.
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ISSN 1932-6203 ISBN Médium
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Notes WOS:000537283500009 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2911
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Auteur Auguet, J.C.; Barberan, A.; Casamayor, E.O.
Titre (up) Global ecological patterns in uncultured Archaea Type Article scientifique
Année 2010 Publication Revue Abrégée Isme J
Volume 4 Numéro 2 Pages 182-190
Mots-Clés 16S/genetics; Archaea/classification/genetics/*physiology DNA; Ribosomal; Ribosomal/genetics *Ecosystem Multivariate Analysis Phylogeny Plankton/classification/genetics RNA; Ribosomal/genetics RNA
Résumé We have applied a global analytical approach to uncultured Archaea that for the first time reveals well-defined community patterns along broad environmental gradients and habitat types. Phylogenetic patterns and the environmental factors governing the creation and maintenance of these patterns were analyzed for c. 2000 archaeal 16S rRNA gene sequences from 67 globally distributed studies. The sequences were dereplicated at 97% identity, grouped into seven habitat types, and analyzed with both Unifrac (to explore shared phylogenetic history) and multivariate regression tree (that considers the relative abundance of the lineages or taxa) approaches. Both phylogenetic and taxon-based approaches showed salinity and not temperature as one of the principal driving forces at the global scale. Hydrothermal vents and planktonic freshwater habitats emerged as the largest reservoirs of archaeal diversity and consequently are promising environments for the discovery of new archaeal lineages. Conversely, soils were more phylogenetically clustered and archaeal diversity was the result of a high number of closely related phylotypes rather than different lineages. Applying the ecological concept of 'indicator species', we detected up to 13 indicator archaeal lineages for the seven habitats prospected. Some of these lineages (that is, hypersaline MSBL1, marine sediment FCG1 and freshwater plSA1), for which ecological importance has remained unseen to date, deserve further attention as they represent potential key archaeal groups in terms of distribution and ecological processes. Hydrothermal vents held the highest number of indicator lineages, suggesting it would be the earliest habitat colonized by Archaea. Overall, our approach provided ecological support for the often arbitrary nomenclature within uncultured Archaea, as well as phylogeographical clues on key ecological and evolutionary aspects of archaeal biology.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1302
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Auteur Eduardo Nole, L.; Bertrand, A.; Mincarone, M.M.; Santos, L.; Fredou, T.; Assuncao, R.; Silva, A.; Menard, F.; Schwamborn, R.; Le Loc'h, F.; Lucena-Fredou, F.
Titre (up) Hatchetfishes (Stomiiformes: Sternoptychidae) biodiversity, trophic ecology, vertical niche partitioning and functional roles in the western Tropical Atlantic Type Article scientifique
Année 2020 Publication Revue Abrégée Prog. Oceanogr.
Volume 187 Numéro Pages 102389
Mots-Clés Brazil; central equatorial atlantic; diet; Diet; Dissolved oxygen; feeding patterns; Gelatinous organisms; Mesopelagic; mesopelagic fishes; midwater fish; Oceanic islands; organic-matter; Seamounts; Stable isotope composition; stable-isotopes; stomiid pisces; yellowfin tuna; zooplankton
Résumé Species of the family Sternoptychidae (hatchetfishes) occur worldwide and play critical roles by sequestering carbon, recycling nutrients, and acting as a key trophic link between epipelagic primary consumers and higher trophic levels in marine ecosystems. Nevertheless, basic knowledge on their ecology is still lacking and their functional ecology remains understudied with respect to composition, organization, functions and environment interactions. Here we integrated comprehensive information collected in the western Tropical Atlantic on the diversity, abundance, distribution and trophic ecology of hatchetfishes, including physicochemical features of their habitats and extensive carbon and nitrogen stable isotope data on its main prey groups. On this basis we defined five functional groups of hatchetfishes with different diet preference, isotopic composition, and vertical abundance peaks and reveal a possible high resource partitioning. Additionally, these species might have a different feeding tie chronology. Hence, hatchetfishes segregate in different ecological groups responding differently to environmental constraints including oxygen concentration and presenting diverse functional roles. As deep-sea species that migrate to epipelagic waters, hatchetfishes may play a key role in the transfer of subsurface photoassimilated carbon to deeper waters, a pathway through which the effects of climate change at the surface are transferred to the deep ocean. Moreover, as consumers of gelatinous organisms, these species convert “gelatinous energy” into “fish energy” readily usable by higher trophic levels, including endangered and commercially important species. This is a crucial trophic relationship that has been historically underestimated due to methodology limitations (e.g., quickly digested gelatinous organisms were probably underestimated in previous studies, based solely on stomach contents). Considering in ecosystem models this trophic relationship, as well as the functional organization of hatchetfishes, is important to properly answer key ecological questions including resource use, carbon transportation, and influence of mesopelagic community in climate change process.
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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 0079-6611 ISBN Médium
Région Expédition Conférence
Notes WOS:000572347900002 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2898
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Auteur Trottet, A.; Leboulanger, C.; Vidussi, F.; Pete, R.; Bouvy, M.; Fouilland, E.
Titre (up) Heterotrophic Bacteria Show Weak Competition for Nitrogen in Mediterranean Coastal Waters (Thau Lagoon) in Autumn Type Article scientifique
Année 2016 Publication Revue Abrégée Microb Ecol
Volume 71 Numéro 2 Pages 304-314
Mots-Clés Bacteria; Dissolved inorganic nitrogen; Ecology; Geoecology/Natural Processes; Inhibitors; Microbial ecology; Microbiology; Nature Conservation; Nitrogen uptake; Phytoplankton; Size fractionation; Water Quality/Water Pollution
Résumé The importance of heterotrophic bacteria relative to phytoplankton in the uptake of ammonium and nitrate was studied in Mediterranean coastal waters (Thau Lagoon) during autumn, when the Mediterranean Sea received the greatest allochthonous nutrient loads. Specific inhibitors and size-fractionation methods were used in combination with isotopic 15N tracers. NO3 − and NH4 + uptake was dominated by phytoplankton (60 % on average) during the study period, which included a flood event. Despite lower biomass specific NH4 + and NO3 uptake rates, free-living heterotrophic bacteria contributed significantly (>30 %) to total microbial NH4 + and NO3 − uptake rates in low chlorophyll waters. Under these conditions, heterotrophic bacteria may be responsible for more than 50 % of primary production, using very little freshly produced phytoplankton exudates. In low chlorophyll coastal waters as reported during the present 3-month study, the heterotrophic bacteria seemed to depend to a greater extent on allochthonous N and C substrates than on autochthonous substrates derived from phytoplankton.
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Volume de collection Numéro de collection Edition
ISSN 0095-3628, 1432-184x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1448
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