Bivalve culture optimisation of three autochthonous species (Ruditapes decussatus,Mytilus galloprovincialisandOstrea edulis) in a central-western Mediterranean lagoon (Porto Pozzo, northern Sardinia)

Three autochthonous species of Bivalve Molluscs were investigated in the Porto Pozzo lagoon (northern Sardinia, central-western Mediterranean Sea). Gametogenic cycle, Condition Indexes and biochemical composition of the grooved carpet-shell, Ruditapes decussatus, from local natural banks were studied during the period July 2009-July 2010. All the factors examined showed a clear seasonal cycle, depending on the reproductive activity and on some environmental variables. Growth, Condition Index and proximate composition of the Mediterranean mussel, Mytilus galloprovincialis, cultured in the oligotrophic lagoon of Porto Pozzo were compared with those obtained in a typical eutrophic ecosystem (the Calich lagoon) and in a mesotrophic basin (the Tortolì lagoon). The trial was carried out in long-line systems in the three lagoons considered, from April to October 2010. The results obtained confirmed a high variability of the three coastal habitats and among the mussel groups cultured in each of them, simultaneously revealing excellent performances, in term of morphometric variables and Condition Index, of the molluscs grown in the Porto Pozzo lagoon. Finally, comparisons of the growth and survival rate of the European flat oysters Ostrea edulis reared using three different experimental tools were performed at two depths. The trial was carried out in the long-line system of the Porto Pozzo basin between June and October 2011. The best results in terms of survival rate and growth performances were achieved at the lower depth of -1 m, regardless of the experimental tools used. Given the results obtained, the observation that Porto Pozzo lagoon is an excellent area for Bivalve Molluscs culture can be supported.