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

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.

Spatial connectivity pattern of expanding gilthead seabream populations and its interactions with aquaculture sites: a combined population genetic and physical modelling approach

“…Significant increase of wild gilthead seabream populations in coastal areas of the Mediterranean Sea and its northward expansion has been documented recently, affecting the structure and productivity of ecosystems 3,5,23 . In this study, 19 neutral microsatellites loci were used to explore geographically fine-scale population processes of gilthead seabream within a short-temporal window in coastal areas of the eastern Adriatic Sea, to gain a deeper understanding of the factors shaping genetic connectivity and structure, in comparing 1586 sampled individuals grouped by fish origin (wild vs farmed vs farmed-associated) and ontogenetic state (juveniles vs adults).…”

“…Annual trend distribution of the Mediterranean sea surface temperature (SST) indicates a warming trend throughout the basin with average values of 0.035 ± 0.007 °C per year 21 . Thus, it could be argued that wild gilthead seabream, as a subtropical Sparid, is taking advantage of the present climate change in terms of increased larval survival and subsequent recruitment success, but also in establishment at the northern limits of distribution areas (e.g., Brittany and Denmark coast) 3,22,23 .…”

The population dynamics of Carcinus maenas (Crustacea: Portunoidea) in a coastal lagoon (Portugal, SW)

“…Despite this plasticity in habitat use, when environmental conditions change, the distribution of this species can also change (Almeida et al 2008), as it actively moves in search of better-quality habitats (Ameyaw-Akumfi and Naylor 1987). The species plays an important role in trophic food webs (Baeta et al 2006), where it can be a prey for several fish species (Hampel et al 2005, Avignon et al 2017 and also an active benthic predator on shellfish, crustacea and polychaetes (Chaves et al 2010), acting as an energy carrier in all systems (Glamuzina et al 2017). Although the species can reach a carapace width of 86 mm (Crothers 1967), in high-density populations the crabs tend to be smaller due to intraspecific competition and cannibalism (Moksnes 2004).…”

Biometry, Distribution and Genetic Characterization of Blue Jack Mackerel Trachurus picturatus (Bowdich, 1825), a Rare Pelagic Fish Species in the Adriatic Sea

“…Žužul et al [14] offered ocean warming as one of the explanations behind the increase in the number of wild gilthead seabream noted in the costal parts of the Adriatic Sea [15]. The authors further argued that it is possible that wild gilthead seabream, as a species that thrives in warmer areas, is becoming more numerous at its northern distribution areas [16], as a consequence of increased larval survival and recruitment success [14].…”