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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 (up) 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 Perry, C.T.; Alvarez-Filip, L.; Graham, N.A.J.; Mumby, P.J.; Wilson, S.K.; Kench, P.S.; Manzello, D.P.; Morgan, K.M.; Slangen, A.B.A.; Thomson, D.P.; Januchowski-Hartley, F.; Smithers, S.G.; Steneck, R.S.; Carlton, R.; Edinger, E.N.; Enochs, I.C.; Estrada-Saldivar, N.; Haywood, M.D.E.; Kolodziej, G.; Murphy, G.N.; Perez-Cervantes, E.; Suchley, A.; Valentino, L.; Boenish, R.; Wilson, M.; Macdonald, C.
Titre (up) Loss of coral reef growth capacity to track future increases in sea level Type Article scientifique
Année 2018 Publication Revue Abrégée Nature
Volume 558 Numéro 7710 Pages 396-+
Mots-Clés atlantic; atoll; bioerosion; calcium-carbonate; carbonate production; climate-change; islands; ocean; patterns; rise
Résumé Sea-level rise (SLR) is predicted to elevate water depths above coral reefs and to increase coastal wave exposure as ecological degradation limits vertical reef growth, but projections lack data on interactions between local rates of reef growth and sea level rise. Here we calculate the vertical growth potential of more than 200 tropical western Atlantic and Indian Ocean reefs, and compare these against recent and projected rates of SLR under different Representative Concentration Pathway (RCP) scenarios. Although many reefs retain accretion rates close to recent SLR trends, few will have the capacity to track SLR projections under RCP4.5 scenarios without sustained ecological recovery, and under RCP8.5 scenarios most reefs are predicted to experience mean water depth increases of more than 0.5 m by 2100. Coral cover strongly predicts reef capacity to track SLR, but threshold cover levels that will be necessary to prevent submergence are well above those observed on most reefs. Urgent action is thus needed to mitigate climate, sea-level and future ecological changes in order to limit the magnitude of future reef submergence.
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ISSN 0028-0836 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2378
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Auteur Mannocci, L.; Baidai, Y.; Forget, F.; Tolotti, M.T.; Dagorn, L.; Capello, M.
Titre (up) Machine learning to detect bycatch risk: Novel application to echosounder buoys data in tuna purse seine fisheries Type Article scientifique
Année 2021 Publication Revue Abrégée Biol. Conserv.
Volume 255 Numéro Pages 109004
Mots-Clés Atlantic Ocean; Drifting fish aggregating devices; Echosounder buoys; Indian Ocean; Random forests; Tropical tuna purse seine fisheries
Résumé The advent of big data and machine learning offers great promise for addressing conservation and management questions in the oceans. Yet, few applications of machine learning exist to mitigate the overexploitation of marine resources. Tropical tuna purse seine fisheries (TTPSF) are distributed worldwide and account for two thirds of the global tuna catch. In these fisheries, the use of Drifting Fish Aggregating Devices (DFADs)? n-made floating objects massively deployed by fishers to increase their tuna catches?results in the incidental catch of non-target species, termed bycatch. We explored the possibility of applying machine learning on echosounder buoys attached to DFADs, representing an unprecedented source of big data, for identifying high bycatch risk at DFADs. We trained random forests algorithms to differentiate between high and low bycatch occurrence based on matched echosounder and onboard observer data for the same DFADs (representing sample sizes of 838 and 2144 in the Atlantic and the Indian Ocean, respectively). Algorithms showed a better performance in the Atlantic Ocean (accuracy of 0.66 versus 0.58 in the Indian Ocean) and were best at detecting the ?high bycatch? occurrence class. These results unravel the potential of machine learning applied to fishers? buoys data for bycatch reduction and improved selectivity in one of the largest fisheries worldwide.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0006-3207 ISBN Médium
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Notes WOS:000630817600001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 3003
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Auteur Bourjea, J.; Clermont, S.; Delgado, A.; Murua, H.; Ruiz, J.; Ciccione, S.; Chavance, P.
Titre (up) Marine turtle interaction with purse-seine fishery in the Atlantic and Indian oceans: Lessons for management Type Article scientifique
Année 2014 Publication Revue Abrégée Biological Conservation
Volume 178 Numéro Pages 74-87
Mots-Clés Atlantic Ocean; Bycatch; Fishery impacts; fishery management; Indian Ocean; Marine turtle
Résumé Bycatch of endangered marine turtles is a growing issue for the management of all fisheries, including the oceanic purse-seine fishery. The aim of this study was to assess the spatial and temporal variation in bycatch rates of these species in the entire European purse-seine fishery operating in the Atlantic and Indian oceans. The study was based on data collected through observer programs from 1995 to 2011. During that period, a total of 15 913 fishing sets were observed, including 6 515 on Drifting Fish Aggregating Devices (DFADs) and 9 398 on free swimming schools, representing a global coverage of 10.3% and 5.1% of the total fishing activity in the Atlantic and Indian Ocean, respectively. Moreover, from 2003 to 2011, 14 124 specific observations were carried out on DFADs to check turtle entanglement in the net covering DFADs. We found that the purse-seine fishery has a very low impact on marine turtles. We estimated that the annual number of individuals incidentally captured was 218 (SD = 150) and 250 (SD = 157) in the Atlantic and Indian Ocean, respectively, with more than 75% being released alive. The present study also investigated the impact of DFADs; which is considered a key conservation issue for this fishery. Drifting objects may play a key role in aggregating juveniles of marine turtles, implying the need for improving their construction to avoid entanglement (e.g. avoiding nets in the structure); however, based on our study it is not the main source of incidental captures of marine turtles in this fishery.
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Numéro d'Appel LL @ pixluser @ collection 349
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Auteur Annasawmy, P.; Ternon, J.F.; Marsac, F.; Cherel, Y.; Behagle, N.; Roudaut, G.; Lebourges-Dhaussy, A.; Demarcq, H.; Moloney, C.L.; Jaquemet, S.; Menard, F.
Titre (up) Micronekton diel migration, community composition and trophic position within two biogeochemical provinces of the South West Indian Ocean: Insight from acoustics and stable isotopes Type Article scientifique
Année 2018 Publication Revue Abrégée Deep-Sea Res. Part I-Oceanogr. Res. Pap.
Volume 138 Numéro Pages 85-97
Mots-Clés Diel vertical migration; East African Coastal province; equatorial atlantic; feeding ecology; Indian South Subtropical Gyre; large pelagic fishes; mesopelagic fishes; mesoscale features; Micronekton; mozambique channel; myctophid fishes; north-atlantic ocean; respiratory carbon; Trophic level; vertical-distribution
Résumé Spatial distribution, community composition and trophic roles of micronekton (crustaceans, fishes and squids) were investigated in the Indian South Subtropical Gyre (ISSG) province and the East African Coastal province (EAFR), by combining acoustic surveys, mid-water trawls and stable isotope analyses from scientific cruises conducted in 2009 and 2010. Mesopelagic micronekton performed diel vertical migrations in both provinces, from deep (400-740 m) to surface (0-200 m) layers at dusk and in the opposite direction at dawn, with some species migrating below 740 m. The EAFR province was more dynamic than the oligotrophic ISSG province, with enhanced eddy activity and enhanced yearly productivity. The active enrichment mechanisms in the EAFR, in terms of available primary production, led to high micronekton acoustic density (as a proxy of micronekton abundance) and large micronekton weight and abundance estimates from trawl data. Particulate organic matter in the EAFR exhibited greater enrichment in C-13 and N-15 compared to the ISSG and, consequently, tissues of selected micronekton organisms in the EAFR were more enriched in N-15 (higher delta N-15 values). In both provinces, micronekton encompassed a wide range of isotopic niches, with large overlaps between species. Micronekton and swordfish in the EAFR had an overlapping range of delta N-15 values, contrasting with the ISSG province where swordfish were two trophic levels higher than the sampled micronekton. Our results provide some evidence that the combined action of riverine input and the dynamics of eddies might influence productivity in the EAFR, and hence the abundance of micronekton and the enrichment of tissues in N-15, compared to the oligotrophic ISSG province.
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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 0967-0637 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2431
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