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Bivalve farming is a major European aquaculture activity, representing 48.5% of total biomass produced. Italy is one of the largest consumers of oysters but local production does not meet the market demand. Italy has approximately 384,000 ha of shallow lagoons in its coastal area, already devoted to extensive aquaculture activities, which could also represent potential locations for Pacific oyster (Crassostrea gigas , Thunberg, 1793) farming. The aim of this study is to enhance Pacific oyster farming in shallow coastal lagoons by testing novel farming technologies and validating an existing bioenergetic growth model (ShellSIM). Commercial performance of Pacific oysters and associated environmental parameters were monitored in two Sardinian coastal lagoons (San Teodoro and Santa Gilla, Italy). Oyster growth and survival were compared during a production cycle for two rearing systems: traditional systems (floating bags or lanterns) and Ortac units. The latter has not been previously tested in coastal lagoons. Measured performances were compared with ShellSIM predictions to evaluate the model's ability to predict growth and the potential production in other coastal lagoons. Results showed that at the end of a six months cycle the oysters mean weight and Condition Index were significantly higher (p value < 0.05) in floating bags than in Ortac, (55.8 ± 0.9 g and 50.1 ± 1.3 g; 4.6 ± 0.1 and 3.9 ± 0.1 respectively). Also, the minimum commercial size (40 g) was reached by 98% and 68% of the oyster farmed in floating bags and Ortac units respectively. On the other hand, oysters reared in the Ortac showed a higher survival than in the floating bags (95.8 ± 0.9% and 82.1 ± 3.4%, respectively). ShellSIM growth predictions were highly correlated with the observed data in both lagoons. However, high values for root mean square deviation (RMSD) indicated that ShellSIM predictions were significantly validated for San Teodoro lagoon but not for Santa Gilla suggesting further tailoring to some environmental conditions to produce more realistic growth predictions. Results of this study indicate that both floating bags and Ortac system should be employed during the production cycle to maximise oysters' survival and growth performances. Furthermore, this study provides a new validated tool to farmers and stakeholders to monitor oysters' performances and estimate productivity in local waters. • Development of site selection and spatial planning tools for oyster aquaculture in new locations. • The ShellSIM growth model adequately predicts pacific oyster growth in shallow Mediterranean coastal lagoons. • Ortac units improve Pacific oyster's survival rate in the early stage of production. [ABSTRACT FROM AUTHOR]

Microplastics debris (<5 mm) are increasingly abundant in the marine environment, therefore, potentially becoming a growing threat for different marine organisms. Through aquatic animals, these can enter in the human food chain, and can be perceived as a risk for consumers' health. Different studies report the presence of particles in marketable shellfish including the world wide commercially grown Pacific oyster Magallana gigas (Thunberg, 1793). The aim of this study is to examine the potential risk of microplastics entering in the human food chain through this shellfish species, investigating the dynamics of the uptake, egestion (faeces) and rejection (pseudofaeces) of microplastics in Pacific oysters under controlled conditions. M. gigas collected from a farm in the San Teodoro lagoon (Italy), were exposed to 60 fluorescent orange polystyrene particles L -1 of known sizes (100, 250 and 500 μm). The uptake of each particle size was 19.4 ± 1.1%, 19.4 ± 2% and 12.9 ± 2% respectively. After exposure M. gigas were left to depurate for 72 h, during which 84.6 ± 2% of the particles taken up were released whilst 15.4 ± 2% were retained inside the shell cavity. No microplastic particles were found in the animals' soft tissues. The results of this study, suggest that depuration is an effective method to reduce presence of large microplastic particles, in the size range 100-500 μm, in M. gigas. Importantly, the data suggests that the burden that could theoretically be up taken by consumers from these shellfish is negligible when compared to other routes., (Copyright © 2019 Elsevier Ltd. All rights reserved.)