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Auteur Annasawmy, P.; Cherel, Y.; Romanov, E.; Le Loc'h, F.; Menard, F.; Ternon, J.-F.; Marsac, F. doi  openurl
  Titre Stable isotope patterns of mesopelagic communities over two shallow seamounts of the south-western Indian Ocean Type Article scientifique
  Année (down) 2020 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.  
  Volume 176 Numéro Pages 104804  
  Mots-Clés biogeochemical provinces; Crustaceans; delta C-13; delta N-15; discrimination factors; feeding ecology; Fish; food-web structure; Micronekton; mozambique channel; particulate organic-matter; Squid; Trophic level; trophic structure; vertical-distribution; water column; yellowfin tuna  
  Résumé The stable carbon (delta C-13) and nitrogen (delta N-15) isotope values of soft tissues of micronekton (crustaceans, squid, mesopelagic fish) and zooplankton were measured from organisms collected on the RV Antea at two seamounts located in the south-western Indian Ocean: La Perouse (summit depth similar to 60 m) and “MAD-Ridge” (thus named in this study; summit depth similar to 240 m). Surface particulate organic matter (POM-Surf) showed higher delta C-13 at the more productive MAD-Ridge than at the oligotrophic La Perouse seamount. Particulate organic matter and zooplankton were depleted in N-15 at La Pemuse pinnacle compared with MAD-Ridge. Gelatinous organisms and crustaceans occupied the lowest and intermediate tmphic levels (TL similar to 2 and 3 respectively) at both seamounts. Mesopelagic fish and smaller-sized squid sampled at both seamounts occupied TL similar to 3 to 4, whereas the large nektonic squid, Ommastrephes bartramii, collected at MAD-Ridge only, exhibited a TL of similar to 5. The delta N-15 values of common open-water mesopelagic taxa were strongly influenced by specimen size and feeding habits at both seamounts, with an increase in delta N-15 values with increasing size. Carnivorous fish species sampled exclusively over the seamounts' flanks and summits exhibited TL values of similar to 4, irrespective of their wide size ranges. The work could not demonstrate any differences in delta C-13 values of mesopelagic fish between the seamounts and the surrounding oceanic areas. The study segregated clusters of mesopelagic organisms according to their delta C-13 and delta N-15 values, with variations in stable isotope values reflecting a complex range of processes possibly linked to productivity as well as biological and ecological traits of the species (size and feeding mode).  
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  ISSN 0967-0645 ISBN Médium  
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  Notes WOS:000556810400002 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2835  
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Auteur Araújo Abrantes de Figueiredo, G.G.; Schwamborn, R.; Bertrand, A.; Munaron, J.-M.; Le Loc'h, F. doi  openurl
  Titre Body size and stable isotope composition of zooplankton in the western tropical Atlantic Type Article scientifique
  Année (down) 2020 Publication Revue Abrégée J. Mar. Syst.  
  Volume 212 Numéro Pages 103449  
  Mots-Clés carbon; delta C-13; delta N-15; fatty-acid; fractionated zooplankton; mesozooplankton; nitrogen isotope; north pacific; particulate organic-matter; patterns; pelagic food-web; Plankton; Predator/prey mass ratio; shelf-slope; Size classes; Trophic level  
  Résumé Size-based approaches are paramount tools for the study of marine food webs. Here, we investigated the relationship between zooplankton body size, stable isotope composition and trophic level (TL) along a large-scale onshore-offshore gradient in the western tropical Atlantic. Samples were obtained on the Brazilian continental shelf, slope and in oceanic waters (off Fernando de Noronha archipelago and Rocas Atoll) in September and October 2015. Zooplankton was sieved into five size fractions. Zooplankton was dominated by copepods, except for the largest (> 2000 mu m) size fraction, that showed a high biovolume of chaetognaths, decapods, and fish larvae. Maximum zooplankton abundance and biovolume was found at the continental slope. POM showed consistently lower delta C-13 than zooplankton, indicating a selective use of C-13-rich primary food sources by zooplankton. Particulate organic matter (POM) was more C-13-enriched in shelf areas (average: -22.8, -23.6 and -24.3% at the shelf, slope and oceanic islands, respectively), probably due to the higher abundance of diatoms nearshore. POM had delta N-15 values between 2.5 and 6.9% (average: 4.0, 4.9 and 4.2% at the shelf, slope and oceanic islands, respectively). Zooplankton delta N-15 and TL increased with body size. The delta N-15 of the 200-500 mu m size fraction was used as baseline for TL estimation. Oceanic areas (average baseline delta N-15 = 5.8% +/- 0.52, n = 14) showed a higher baseline delta N-15 than the shelf (average = 3.9% +/- 0.69, n = 9) and the slope areas (average = 3.1% +/- 0.93, n = 9). In spite of differing baselines, the delta N-15 data produced a consistent pattern of log-linear increase in TL with increasing size, in all areas. The choice of input trophic enrichment factor (TEF) values only slightly changed the log10 (body size) vs TL slopes, but this choice had a considerable effect on the estimates of predator/prey size ratio (PPSR) and predator/prey mass ratio (PPMR). Using a TEF above 2.3 leads to unrealistic PPSR and PPMR estimates. Overall average slope was 0.59 +/- 0.08 TL mu m(-1) with TEF = 2.3 and 0.42 +/- 0.07 TL mu m(-1) with TEF = 3.2.  
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  ISSN 0924-7963 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2884  
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Auteur Planque, B.; Mullon, C. doi  openurl
  Titre Modelling chance and necessity in natural systems Type Article scientifique
  Année (down) 2020 Publication Revue Abrégée ICES J. Mar. Sci.  
  Volume 77 Numéro 4 Pages 1573-1588  
  Mots-Clés chaos; chaos theory; comanagement; community management; complexity; constraints; fisheries management; food-web dynamics; marine ecosystems; nonlinear systems; parametric management; participatory modelling; recruitment; time; uncertainty; viability theory  
  Résumé Nearly 30 years ago, emerged the concept of deterministic chaos. With it came sensitivity to initial conditions, nonlinearities, and strange attractors. This constituted a paradigm shift that profoundly altered how numerical modellers approached dynamic systems. It also provided an opportunity to resolve a situation of mutual misunderstanding between scientists and non-scientists about uncertainties and predictability in natural systems. Our proposition is that this issue can be addressed in an original way which involves modelling based on the principles of chance and necessity (CaN). We outline the conceptual and mathematical principles of CaN models and present an application of the model to the Barents Sea food-web. Because CaN models rely on concepts easily grasped by all actors, because they are explicit about knowns and unknowns and because the interpretation of their results is simple without being prescriptive, they can be used in a context of participatory management. We propose that, three decades after the emergence of chaos theories, CaN can be a practical step to reconcile scientists and non-scientists around the modelling of structurally and dynamically complex natural systems, and significantly contribute to ecosystem-based fisheries management.  
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  ISSN 1054-3139 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2888  
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Auteur Bachiller, E.; Albo-Puigserver, M.; Gimenez, J.; Grazia Pennino, M.; Mari-Mena, N.; Esteban, A.; Lloret-Lloret, E.; Jadaud, A.; Carro, B.; Maria Bellido, J.; Coll, M. doi  openurl
  Titre A trophic latitudinal gradient revealed in anchovy and sardine from the Western Mediterranean Sea using a multi-proxy approach Type Article scientifique
  Année (down) 2020 Publication Revue Abrégée Sci Rep  
  Volume 10 Numéro 1 Pages 17598  
  Mots-Clés body condition; daily ration; diel feeding intensity; diversity; ecology; engraulis-encrasicolus l.; food-web; niche overlap; pilchardus; small pelagic fish  
  Résumé This work combines state-of-the-art methods (DNA metabarcoding) with classic approaches (visual stomach content characterization and stable isotope analyses of nitrogen (delta N-15) and carbon (delta C-13)) to investigate the trophic ecology of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) at high taxonomic and spatial resolution in the Western Mediterranean Sea. Gut contents observed are in accordance with the dietary plasticity generally described for anchovy and sardine, suggesting a diet related to the opportunistic ingestion of available prey in a certain area and/or time. Genetic tools also showed modest inter-specific differences regarding ingested species. However, inter-specific and intra-specific differences in ingested prey frequencies and prey biomass reflected a latitudinal signal that could indicate a more effective predation on large prey like krill by anchovy versus sardine, as well as a generalized higher large prey ingestion by both species southwards. In fact, both species presented lower delta N-15 in the northernmost area. This latitudinal gradient indicates changes in the trophic ecology of anchovy and sardine that coincide with previously described better biological conditions for fish in the southern part of the study area as well as higher landings of both species in recent years.  
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  ISSN 2045-2322 ISBN Médium  
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  Notes WOS:000585186800005 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2921  
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Auteur Danovaro, R.; Fanelli, E.; Canals, M.; Ciuffardi, T.; Fabri, M.-C.; Taviani, M.; Argyrou, M.; Azzurro, E.; Bianchelli, S.; Cantafaro, A.; Carugati, L.; Corinaldesi, C.; de Haan, W.P.; Dell'Anno, A.; Evans, J.; Foglini, F.; Galil, B.; Gianni, M.; Goren, M.; Greco, S.; Grimalt, J.; Guell-Bujons, Q.; Jadaud, A.; Knittweis, L.; Lopez, J.L.; Sanchez-Vidal, A.; Schembri, P.J.; Snelgrove, P.; Vaz, S. doi  openurl
  Titre Towards a marine strategy for the deep Mediterranean Sea: Analysis of current ecological status Type Article scientifique
  Année (down) 2020 Publication Revue Abrégée Mar. Pol.  
  Volume 112 Numéro Pages 103781  
  Mots-Clés atmospheric deposition; Deep-sea ecosystems; downward particle fluxes; food-web structure; Marine strategy framework directive; Mediterranean basin; mercury bioaccumulation; particulate matter; polycyclic aromatic-hydrocarbons; seismic surveys; stable-isotopes; submarine canyons; trophic ecology  
  Résumé The Marine Strategy Framework Directive (MSFD), introduced in June 2008, was adopted to achieve a Good Environmental Status (GES) in the Ell's marine waters and to protect resources of socio-economic interest. The MSFD exerts to the marine area over which a Member State exercises jurisdictional rights in accordance with the United Nations Convention on the Law of the Sea (UNCLOS), including the deep-sea waters, seafloor and subseafloor of the Exclusive Economic Zones (EEZ). However, currently the MSFD focuses on coastal habitats and the shallow-water seafloor to the detriment of the deeper habitats. Despite the huge dimension of the deep sea (below 200 m of depth) covering more than 65% of the Earth's surface and including >95% of the global biosphere, the relevance of the dark portion of the seas and oceans is still almost completely neglected. Given the important bi-directional links between shallow and deep ecosystems, there is a clear need for extending the implementation of the MSFD into the deep sea, to define a sound ecosystem-based approach for the management and protection of deep-sea ecosystems and attain GES. We assembled data on drivers, anthropogenic pressures and impacts concerning the MSFD descriptors pertaining to the Mediterranean deep sea. We list deep-sea monitoring activities and the main sources providing benchmark conditions, and discuss knowledge and geographic coverage gaps. MSFD descriptors apply to the deep sea as to coastal waters, and ought to be monitored contemporaneously. We provide recommendations for guidelines for future deep-sea monitoring in the Mediterranean Sea.  
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  ISSN 0308-597x ISBN Médium  
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  Notes WOS:000515208000012 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2749  
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