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Auteur 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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Langue English Langue du Résumé Titre Original
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ISSN 0171-8630 ISBN Médium
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