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Population substructure of Sepia officinalis sampled along the Tunisian coastline was studied. We have scored the genetic variation of the mitochondrial gene cytochrome oxidase 1. A total of 20 specimens from four sampling sites were analysed and revealed 12 different haplotypes. Haplotype diversity showed a decreasing north to south gradient which may be explained by the hydrogeography of the study area. The overall estimate of genetic divergence (FST) revealed significant genetic differentiation between the pair-wise population comparisons supported by the AMOVA analysis which reveals significant genetic divergence. Finally, populations showed an excess of rare haplotypes. The mismatch distribution and several population genetic statistics indicate that the excess of rare variants is due to a recent expansion for Djerba and Kelibia populations. For Rades and Bizerte populations a constant population size was detected. These findings are important for fisheries management to preserve this marine resource for long-term utilization.

Gilthead sea bream Sparus aurata is one of the most commonly farmed marine species in the Mediterranean Sea. In Tunisia, this aquaculture product is economically affordable for the consumers; however its nutritional properties are not well documented. This study aims to establish a comparative analysis of the fatty acid profiles of the fillet of wild and farmed sea bream from Tunisian coast. Samples of wild and floating net cage farmed sea bream were obtained in the same season. Fatty acid composition and lipid quality indices were assessed. The obtained results show no significant difference in terms of total fatty acid composition between samples from intensive farming in floating net cages and wild fish. However, the samples from the farming net cages were characterized by significantly higher levels of docosahexaenoic acid (C22:6n-3) and linoleic acid (C18:2n-6) against high levels of arachidonic acid (C20:4n-6), eicosapentaenoic acid (C20:5n- 3) and α-linolenic acid (C18:3n-3) in wild specimens. From a nutritional point of view, the docosahexaenoic acid content and the values of some indicators of the nutritional quality of lipids such as the flesh lipid quality (FLQ) and the thrombogenic index (TI) show slightly higher nutritional value of farmed vs. wild gilthead.

International audience; Concentrations of cadmium (Cd), copper (Cu), mercury (Hg) and zinc (Zn) were determined by atomic absorption spectrophotometry in the muscle tissues (arms and mantle) of three commercial cephalopods (Loligo vulgaris, Octopus vulgaris and Sepia officinalis) caught in three different Tunisian coastal regions. The highest concentrations found correspond to the essential elements Cu and Zn. Octopuses and cuttlefish showed the highest levels of those elements while squid presented with significantly higher values of Hg in both muscular tissues. This may be related to different feeding behavior and detoxification processes among benthic and pelagic cephalopods. Variation of element concentrations between seasons was different between species and seemed to be mostly dependent on the sampling site. From a public health standpoint, average concentrations of Cd, Cu, Hg and Zn measured in edible tissues of cephalopods from this study did not reveal, in general, any risk for consumers. The estimated Target Hazard Quotients (THQs) for Cd and Hg for consumers of the selected species were below 1 and within the safety range for human health. Moreover, their consumption could provide in an important contribution to the daily dietary intake of Cu for the Tunisian population, especially regarding the consumption of octopus and cuttlefish muscles.