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Auteur Sebastian, M.; Smith, A.F.; Gonzalez, J.M.; Fredricks, H.F.; Van Mooy, B.; Koblizek, M.; Brandsma, J.; Koster, G.; Mestre, M.; Mostajir, B.; Pitta, P.; Postle, A.D.; Sanchez, P.; Gasol, J.M.; Scanlan, D.J.; Chen, Y.
Titre Lipid remodelling is a widespread strategy in marine heterotrophic bacteria upon phosphorus deficiency Type Article scientifique
Année 2016 Publication Revue Abrégée Isme J.
Volume 10 Numéro 4 Pages 968-978
Mots-Clés 2 enzymes; agrobacterium-tumefaciens; bacterioplankton groups; Ecology; Mediterranean Sea; mesocosm experiment; microbial food-web; north-atlantic ocean; nutrient limitation; phosphate starvation
Résumé Upon phosphorus (P) deficiency, marine phytoplankton reduce their requirements for P by replacing membrane phospholipids with alternative non-phosphorus lipids. It was very recently demonstrated that a SAR11 isolate also shares this capability when phosphate starved in culture. Yet, the extent to which this process occurs in other marine heterotrophic bacteria and in the natural environment is unknown. Here, we demonstrate that the substitution of membrane phospholipids for a variety of non-phosphorus lipids is a conserved response to P deficiency among phylogenetically diverse marine heterotrophic bacteria, including members of the Alphaproteobacteria and Flavobacteria. By deletion mutagenesis and complementation in the model marine bacterium Phaeobacter sp. MED193 and heterologous expression in recombinant Escherichia coli, we confirm the roles of a phospholipase C (PlcP) and a glycosyltransferase in lipid remodelling. Analyses of the Global Ocean Sampling and Tara Oceans metagenome data sets demonstrate that PlcP is particularly abundant in areas characterized by low phosphate concentrations. Furthermore, we show that lipid remodelling occurs seasonally and responds to changing nutrient conditions in natural microbial communities from the Mediterranean Sea. Together, our results point to the key role of lipid substitution as an adaptive strategy enabling heterotrophic bacteria to thrive in the vast P-depleted areas of the ocean.
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ISSN 1751-7362 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1624
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Auteur Shannon, L.J.; Coll, M.; Yemane, D.; Jouffre, D.; Neira, S.; Bertrand, A.; Diaz, E.; Shin, Y.J.
Titre Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends Type Article scientifique
Année 2010 Publication Revue Abrégée ICES J. Mar. Sci.
Volume 67 Numéro 4 Pages 807-832
Mots-Clés adriatic sea; central chile; comparative approach; demersal resources; fishing impacts; food-web; global fisheries; humboldt current system; indicator; nw mediterranean sea; pelagic fish; regime shifts; southern benguela; upwelling
Résumé Shannon, L. J., Coll, M., Yemane, D., Jouffre, D., Neira, S., Bertrand, A., Diaz, E., and Shin, Y-J. 2010. Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends. – ICES Journal of Marine Science, 67: 807-832.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1054-3139 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 482
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Auteur Sirot, C.; Gronkjaer, P.; Pedersen, J.B.; Panfili, J.; Zetina-Rejon, M.; Tripp-Valdez, A.; Ramos-Miranda, J.; Flores-Hernandez, D.; Sosa-Lopez, A.; Darnaude, A.M.
Titre Using otolith organic matter to detect diet shifts in Bardiella chrysoura, during a period of environmental changes Type Article scientifique
Année 2017 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 575 Numéro Pages 137-152
Mots-Clés aquatic ecosystems; Bairdiella chrysoura; climate-change; Coastal ecosystem; fish otoliths; food-web; movement patterns; prey availability; Stable isotope analysis; stable-isotope analysis; survival; temporal-changes; terminos lagoon; Trophic ecology; Trophic interactions
Résumé Accurate knowledge on fish trophic ecology and its modifications is crucial for understanding the impact of global change on ecosystems. In this context, we investigated the value of the delta C-13 and delta N-15 of otolith soluble organic matter (SOM) for identifying temporal diet shifts in American silver perch Bairdiella chrysoura over a 30-yr period characterized by strong changes in its population size and habitats within the Terminos Lagoon (Mexico). We first compared the otolith SOM isotopic signatures from present-clay adults to those of muscle and the main local prey. Our results suggest that otolith SOM can be confidently extracted and analyzed for both present and past otoliths of this species. The mean otolith SOM signatures obtained (-15.92 +/- 1.35%, for delta C-13 and 9.38 +/- 0.93%, for delta N-15) were consistent with those of the diet as 85% of the individual signatures were included within the prey isotopic niche area. Moreover, this study supports a trophic enrichment factor between diet and otolith (TEFdiet-otolith) close to 0 for delta N-15, while for delta C-13, the TEFololith-muscle of +0.02% warrants further investigation. Then, we compared past and contemporary otolith SOM signatures to investigate temporal diet shifts in B. chrysoura. This showed that 613C and delta N-15 differed significantly between the past and present period even if the temporal shift remained relatively small (respectively +1.17%, and 0.55%). The present study substantiates the use of otolith SOM delta C-13 and delta N-15 as a proxy of fish present and past trophic position, opening the possibility for major progress in studies of temporal changes in food web ecology.
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Volume de collection Numéro de collection Edition
ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2172
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Auteur Valls, A.; Coll, M.; Christensen, V.
Titre Keystone species : toward an operational concept for marine biodiversity conservation Type Article scientifique
Année 2015 Publication Ecological Monographs Revue Abrégée
Volume 85 Numéro 1 Pages 29-47
Mots-Clés classification tree; Ecopath model; food-web structure; index of keystoneness; keystone species; marine ecosystems; Meta-analysis; mixed-trophic impact; rank correlation tests; scoring method
Résumé Various definitions and indices have been proposed in the literature to identify keystone species. In this study, we intended to make the concept of keystone species operational for marine biodiversity conservation. We used an exclusive definition of keystone species, based on the original concept of keystone predator, and derived a new functional index of keystoneness (KS) from an ecosystem-modeling approach. First, several KS indices were formulated, by combining measures of the mixed-trophic impact (MTI) and biomass of species. Then, a meta-analysis was performed, based on 101 published Ecopath food-web models, selected with a scoring method, and representative of the variety of marine ecosystems worldwide. The indices were applied to the models, and two statistical methods were compared to select the most promising KS index. Rank correlation tests were performed to assess the balance between the contribution of the impact and biomass components to the different KS indices. In addition, a classification tree was implemented, based on ecosystem-specific thresholds applied to the latter species traits, and used to confirm the identified keystone species. The selected index obtained the highest number of models with positive results from both the rank correlation tests and the classification tree. We also demonstrated the limitations of existing KS indices previously applied in the literature. Species were ranked according to their estimates of keystoneness with the selected KS index, so that potential keystone species were quantitatively identified in the 101 modeled food webs. The standardized modeling approach allowed for a comparison of the identified keystone species across models: cartilaginous fishes and toothed whales obtained the highest occurrences. Finally, the selected KS index was applied to the well-known case study of Prince William Sound (Alaska, USA). Potentially significant anthropogenic (fishing) impacts on keystone species were also considered and discussed. The operational methodology presented is directly applicable to marine food webs, and may be adapted to other (freshwater or terrestrial) systems.
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Volume de collection Numéro de collection Edition
ISSN 0012-9615 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1114
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Auteur Villeger, S.; Brosse, S.; Mouchet, M.; Mouillot, D.; Vanni, M.J.
Titre Functional ecology of fish: current approaches and future challenges Type Article scientifique
Année 2017 Publication Revue Abrégée Aquat. Sci.
Volume 79 Numéro 4 Pages 783-801
Mots-Clés biodiversity; centrarchid fishes; coral-reef fishes; dietary-morphological relationships; ecosystem processes; Ecosystem services; fish; food-web; fresh-water fish; functional trait; global change; labrid fishes; life-history strategies; ocean; phosphorus-limitation; population regulation; river
Résumé Fish communities face increasing anthropogenic pressures in freshwater and marine ecosystems that modify their biodiversity and threaten the services they supply to human populations. To address these issues, studies have been increasingly focusing on functions of fish that are linked to their main ecological roles in aquatic ecosystems. Fish are indeed known to control other organisms through predation, mediate nutrient fluxes, and can act as ecosystem engineers. Here for each of the key functions played by fish, we present the functional traits that have already been used to assess them. We include traits measurable from observations on living individuals, morphological features measured on preserved organisms or traits categorized using information from the literature, and we discuss their respective advantages and limitations. We then list future research directions to foster a more complete functional approach for fish ecology that needs to incorporate functional traits describing, food provisioning and cultural services while accounting more frequently for intraspecific variability. Finally, we highlight ecological and evolutionary questions that could be addressed using meta-analyses of large trait databases, and how a trait-based framework could provide valuable insights on the mechanistic links between global changes, functional diversity of fish assemblages, and ecosystem services.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1015-1621 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2211
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