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Auteur (up) Brosset, P.; Le Bourg, B.; Costalago, D.; Banaru, D.; Van Beveren, E.; Bourdeix, J.-H.; Fromentin, J.-M.; Menard, F.; Saraux, C.
Titre Linking small pelagic dietary shifts with ecosystem changes in the Gulf of Lions Type Article scientifique
Année 2016 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 554 Numéro Pages 157-171
Mots-Clés anchovy; anchovy engraulis-encrasicolus; climate; Dietary overlap; fish; food-web; NW Mediterranean; nw mediterranean sea; plankton; regime shifts; Sardine; size-fractionated zooplankton; southern benguela; Sprat; stable-isotope ratios; Trophic ecology
Résumé Since 2008, a severe decrease in size and body condition together with a demographic truncation has been observed in the sardine (secondarily in anchovy) population of the Gulf of Lions (NW Mediterranean Sea). In parallel, sprat biomass, which was negligible before, has increased tenfold. All of these changes have strongly affected the regional fisheries. Using trophic and isotopic data from contrasting periods of low versus high growth and condition, we investigated potential changes in diet and interspecific feeding interactions through time. Evidence of resource partitioning was found between sprat and both anchovy and sardine in 2004 and 2005. Since 2010, the isotopic niches of the 3 species have tended to overlap, suggesting higher risk of competition for food resources. Moreover, the wider trophic niche of sprat indicates higher variability in individual diets. Anchovy and sardine diet varied through time, with a high proportion of large copepods or cladocerans in periods of high growth and condition (1994 and 2007, respectively) versus a dominance of small copepods in the present (2011-2012). Furthermore, an important reduction in prey diversity was also identified in the diet of both anchovy and sardine during the most recent period. Our results support the hypothesis that changes in small pelagic fish growth, size and body condition and ultimately biomass could be due to bottom-up control characterized by changes in food availability and increasing potential trophic competition.
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ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1642
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Auteur (up) Escalas, A.; Ferraton, F.; Paillon, C.; Vidy, G.; Carcaillet, F.; Salen-Picard, C.; Le Loc'h, F.; Richard, P.; Darnaude, A.M.
Titre Spatial variations in dietary organic matter sources modulate the size and condition of fish juveniles in temperate lagoon nursery sites Type Article scientifique
Année 2015 Publication Revue Abrégée Estuar. Coast. Shelf Sci.
Volume 152 Numéro Pages 78-90
Mots-Clés coastal lagoon; continental inputs; diet; fish; food webs; fresh-water flow; gilthead sea bream; isotope ratios; lagoon; marine nurseries; nursery; sole solea-solea; sparus-aurata; Stable isotopes; stable-isotopes; trophic ecology
Résumé Effective conservation of marine fish stocks involves understanding the impact, on population dynamics, of intra-specific variation in nursery habitats use at the juvenile stage. In some regions, an important part of the catching effort is concentrated on a small number of marine species that colonize coastal lagoons during their first year of life. To determine the intra-specific variation in lagoon use by these fish and their potential demographic consequences, we studied diet spatiotemporal variations in the group 0 juveniles of a highly exploited sparid, the gilthead seabream (Sparus aurata L), during their similar to 6 months stay in a NW Mediterranean lagoon (N = 331, SL = 25-198 mm) and traced the origin of the organic matter in their food webs, at two lagoon sites with contrasted continental inputs. This showed that the origin (marine, lagoonal or continental) of the organic matter (OM) available in the water column and the sediment can vary substantially within the same lagoon, in line with local variations in the intensity of marine and continental inputs. The high trophic plasticity of S. aurata allows its juveniles to adapt to resulting differences in prey abundances at each site during their lagoon residency, thereby sustaining high growth irrespective of the area inhabited within the lagoon. However, continental POM incorporation by the juveniles through their diet (of 21-37% on average depending on the site) is proportional to its availability in the environment and could be responsible for the greater fish sizes (of 28 mm SL on average) and body weights (of 40.8 g on average) observed at the site under continental influence in the autumn, when the juveniles are ready to leave the lagoon. This suggests that continental inputs in particulate OM, when present, could significantly enhance fish growth within coastal lagoons, with important consequences on the local population dynamics of the fish species that use them as nurseries. As our results indicate that continental OM can represent up to 62% of the flesh of the juveniles originating from these ecosystems, particular care should be taken to preserve or improve the chemical quality of riverine inputs to coastal lagoons. (C) 2014 Elsevier Ltd. All rights reserved.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0272-7714 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1192
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Auteur (up) Mellon-Duval, C.; Harmelin-Vivien, M.; Metral, L.; Loizeau, V.; Mortreux, S.; Roos, D.; Fromentin, J.-M.
Titre Trophic ecology of the European hake in the Gulf of Lions, northwestern Mediterranean Sea Type Article scientifique
Année 2017 Publication Revue Abrégée Sci. Mar.
Volume 81 Numéro 1 Pages 7-18
Mots-Clés age; bay; biscay; celtic sea; diet; foodweb; glm; habitat; Merluccius merluccius; merluccius-merluccius l.; predator-prey relationships; Size; small pelagic fish; spatiotemporal variation; stable-isotope ratios; Stable isotopes; Stomach contents
Résumé The European hake, Merluccius merluccius, is an important resource for Mediterranean fisheries. This study focuses on juvenile and adult hake feeding ecology in the Gulf of Lions, using information from scientific surveys carried out during two seasons and three years (2004- 2006). Stomach content and stable isotope (delta N-15, delta C-13) analyses were performed, and the main factors explaining variations in delta N-15 were investigated using GLMs. In the Gulf of Lions, hake mostly fed on crustaceans and fish and a dominant piscivorous regime was reached at 15 cm total length. Pelagic fish (sardine, anchovy and small blue whiting) were the main source of prey (40%- 80%) and cannibalism was low (< 5%). The results confirmed that hake is an opportunistic feeder and also showed that the size and diversity of prey vary among hake size classes, probably as a result of the different spatial distribution and/or foraging migrations. The present study finally postulates that the unbalanced sex ratio (80% female against 20% male) observed at the adult stage could be related to the combination of growth pattern differences, diet and exploitation rate on the continental shelf, where the males spend a longer period of time.
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ISSN 0214-8358 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2121
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Auteur (up) Morat, F.; Letourneur, Y.; Blamart, D.; Pecheyran, C.; Darnaude, A.M.; Harmelin-Vivien, M.
Titre Offshore-onshore linkages in the larval life history of sole in the Gulf of Lions (NW-Mediterranean) Type Article scientifique
Année 2014 Publication Revue Abrégée Estuarine Coastal and Shelf Science
Volume 149 Numéro Pages 194-202
Mots-Clés age; bristol channel; common sole; fish otoliths; isotope ratios; microchirus-variegatus; nursery grounds; otolith microchemistry; Rhone River; river flood event; sea; seasonal-variation; shape-analysis; Solea solea; stable isotope
Résumé Understanding individual dispersion from offshore natal areas to coastal nurseries during pelagic larval life is especially important for the sustainable management of exploited marine fish species. For several years, the hatching period, the larval life duration, the average growth rate and the otolith chemical composition (delta C-13, delta O-18, Sr:Ca and Ba:Ca) during the larval life were studied for young of the year (YOY) of sole collected in three main nurseries of the Gulf of Lions (GoL) (Thau, Mauguio and Berre). We investigated the spatial variation in the origin of the sole larvae which colonised the nurseries around the GoL, and whether temporal differences in environmental conditions during this life stage affected growth and larval life duration. The hatching period ranges from October to March, depending on year and site. Average ages at metamorphosis varied between 43 and 50 days, with the lowest and highest values consistently found for Mauguio and Berre, respectively. Otolith growth rates ranged between 2.7 and 3.2 mu m d(-1), with the lowest values in Thau and Mauguio and the highest in Berre. Otolith chemical composition during the larval life also varied, suggesting contrasted larval environmental histories in YOY among nurseries. In fishes from Berre and Mauguio, larval life was more influenced by the Rhone River, showing consistently higher larval Ba:Ca ratios (10/23 mu mol mol(-1)) and lower delta C-13 (-6.5/-6.1 parts per thousand) and delta O-18 values (-1.6/0.1 parts per thousand) than for Thau (with Ba:Ca ratios < 8 mu mol mol(-1), delta C-13 similar to-2.3 parts per thousand and delta O-18 similar to 1.5 parts per thousand). Differences in larval otolith composition were observed for 2004, with higher Ba:Ca and lower delta C-13 and delta O-18 values than in the two other years. These differences were explained by changes in composition and chemical signatures of water masses after an exceptional flooding event of the Rhone River in late 2003. (C) 2014 Elsevier Ltd. All rights reserved.
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ISSN 0272-7714 ISBN Médium
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Notes <p>ISI Document Delivery No.: AW3ZF<br/>Times Cited: 0<br/>Cited Reference Count: 75<br/>Morat, Fabien Letourneur, Yves Blamart, Dominique Pecheyran, Christophe Darnaude, Audrey M. Harmelin-Vivien, Mireille<br/>PACA Region; Total foundation; Agence de l'Eau Rhone Mediterranee Corse; French National Research Agency (ANR) through the young scientist program LAGUNEX [07-JCJC-0135]<br/>Fabien Morat was funded by Ph.D stipends from the PACA Region, the Total foundation, and the Agence de l'Eau Rhone Mediterranee Corse and by the French National Research Agency (ANR) through the young scientist program LAGUNEX (07-JCJC-0135). We thank Jean-Pierre Quignard and fishermen for Thau and Mauguio lagoons samples, and Gipreb members for Berre lagoon samples. The authors express their thanks to Christian Marschal and Chantal Mahe-Bezac for their technical help in age estimation, Olivier Radakovitch for elemental data of the Rhone River waters, and Michael Paul, a native English speaker scientific translator, for language correction. We are grateful to anonymous reviewers for their valuable suggestions and criticisms that have enabled us to improve the article.<br/>Academic press ltd- elsevier science ltd<br/>London</p> Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1169
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Auteur (up) Navarro, J.; Saez-Liante, R.; Albo-Puigserver, M.; Coll, M.; Palomera, I.
Titre Feeding strategies and ecological roles of three predatory pelagic fish in the western Mediterranean Sea Type Article scientifique
Année 2017 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.
Volume 140 Numéro Pages 9-17
Mots-Clés diet; ecosystem structure; iberian peninsula; indian-ocean; isotope ratios; Marine predators; Pelagic ecosystem; Stable isotopes; stable-isotopes; Stomach contents; swordfish; top predators; Trophic ecology; trophic level; xiphias-gladius; Yellowfin tuna
Résumé Knowing the feeding ecology of marine predators is pivotal to developing an understanding of their ecological role in the ecosystem and determining the trophic relationships between them. Despite the ecological importance of predatory pelagic fish species, research on these species in the Mediterranean Sea is limited. Here, by combining analyses of stomach contents and stable isotope values, we examined the feeding strategies of swordfish, Xiphias gladius, little tunny, Euthynnus alletteratus and Atlantic bonito, Sarda sarda, in the western Mediterranean Sea. We also compared the trophic niche and trophic level of these species with published information of other sympatric pelagic predators present in the ecosystem. Results indicated that, although the diet of the three species was composed mainly by fin-fish species, a clear segregation in their main feeding strategies was found. Swordfish showed a generalist diet including demersal species such as blue whiting, Micromesistius poutassou, and European hake, Merluccius merluccius, and pelagic fin-fish such as barracudina species (Arctozenus risso and Lestidiops jayakari) or small pelagic fish species. Little tunny and Atlantic bonito were segregated isotopically between them and showed a diet basically composed of anchovy, Engraulis encrasicolus, and round sardinella, Sardinella aurita, and sardines, Sardina pilchardus, respectively. This trophic segregation, in addition to potential segregation by depth, is likely a mechanism that allows their potential coexistence within the same pelagic habitat. When the trophic position of these three predatory pelagic fish species is compared with other pelagic predators such as bluefin tuna, Thunnus thynnus, and dolphinfish, Coryphaena hippurus, present in the western Mediterranean Sea, we found that they show similar intermediate trophic position in the ecosystem. In conclusion, the combined stomach and isotopic results highlight, especially for little tunny and Atlantic bonito, the trophic importance of Clupeoid species in their diet. In addition, the importance of demersal resources for swordfish provides evidence for the pelagic-demersal coupling of the ecosystem and the need to manage marine resources in an integrated way. (C) 2016 Elsevier Ltd. All rights reserved.
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Volume de collection Numéro de collection Edition
ISSN 0967-0645 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2175
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