Morphological identification and DNA barcoding used for diet analysis of gilthead seabream (Sparus aurata) in its expanding northerly range

¹ UMR Biologie des Organismes et Ecosystèmes Aquatiques (BOREA, UMR 7208), MNHN/Sorbonne Universités/UMPC/UCBN/CNRS/IRD/UA, Museum National d’Histoire Naturelle, Station de Biologie Marine de Concarneau, Place de la Croix, 29900 Concarneau, France
² PRES LUNAM Université du Maine, Laboratoire Mer, Molécules, Santé (EA 2160), Institut Universitaire Mer et Littoral FR3473 CNRS, Avenue Olivier Messiaen, 72085 Le Mans cedex 9, France
³ UMR Biologie des Organismes et Ecosystèmes Aquatiques (BOREA, UMR 7208), MNHN/Sorbonne Universités/UMPC/UCBN/CNRS/IRD/UA, Museum National d’Histoire Naturelle, 57 rue Cuvier, 75005 Paris, France

^a Corresponding author: savignon@mnhn.fr

Received: 30 August 2016
Accepted: 28 November 2016

Abstract

The gilthead seabream, Sparus aurata, is common in the Mediterranean Sea and along the Atlantic coasts of Portugal, Spain and France. Abundance of S. aurata has recently increased along the Brittany coast, showing good adaptation and acclimatisation to northern waters away from its original distribution range. The physiological adaptations (diet, reproduction, growth) of this fish to colder water could even lead to its colonisation of the English Channel. The ability to eat and digest hard prey makes this fish an important consumer of bivalves. The aim of this study was to make a preliminary evaluation of the diet of the gilthead seabream in its northern range of distribution. Prey items from stomach contents of wild adults from various sites along the East Atlantic coast of France to the English Channel were identified morphologically when it was possible, e.g. in presence of decapod appendices, shells of bivalves, or using DNA barcoding. Diet composition was analysed against sites, fish length and month of sampling using the frequency of occurrence (%F) and weight relative proportion (%W). Results showed that the diet of S. aurata was mainly composed of bivalves, malacostracans and gastropods with a huge dominance of Mytilus sp. (%F = 51.5 and %W = 40.2). This first diet analysis of individuals from the northern range of the species distribution showed its ability, as an opportunistic feeder, to find prey in newly colonised ecosystems and its preference for some organisms, especially mussels.