Linking small pelagic dietary shifts with ecosystem changes in the Gulf of Lions
|Author(s)||Brosset Pablo1, 2, Le Bourg Baptiste3, 5, Costalago David4, Banaru Daniela3, Van Beveren Elisabeth2, Bourdeix Jean-Herve2, Fromentin Jean-Marc2, Menard Frederic3, Saraux Claire2|
|Affiliation(s)||1 : Univ Montpellier, IFREMER, UMR MARBEC, IRD,UM,CNRS, F-34203 Sete, France.
2 : IFREMER, IRD, CNRS, UMR MARBEC,UM, F-34203 Sete, France.
3 : Univ Toulon & Var, Aix Marseille Univ, Mediterranean Inst Oceanog, CNRS,IRD,UM 110, F-13288 Marseille, France.
4 : Stockholm Univ, Dept Ecol Environm & Plant Sci, S-10691 Stockholm, Sweden.
5 : Univ Liege, Lab Oceanol, MARE Ctr, B-4000 Liege, Belgium.
|Source||Marine Ecology Progress Series (0171-8630) (Inter-research), 2016-07 , Vol. 554 , P. 157-171|
|WOS© Times Cited||33|
|Keyword(s)||Trophic ecology, Anchovy, Sardine, Sprat, Dietary overlap, NW Mediterranean|
|Abstract||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.|