Oyster supply and storing plan. Deliverable 4.2 of the LIFE NatuReef project: Nature-based reef solution for coastal protection and marine biodiversity enhancement. LIFE22-NAT-IT-LIFE-NatuReef/101113742

Native oyster supply is a key limiting step in oyster restoration projects (Preston et al. 2020). Sourcing oysters from outside the local area can present significant biosecurity risks, which are time consuming and costly to address and impossible to eliminate completely. This is why our main supply of oysters will be local or regional wild stocks (broodstock, mean individual size 5-8 cm). Local stock may have adaptations suited for survival in the area and existing genetic structure in the population is maintained, ensuring genetic diversity. However, when considering using wild stocks, the impact on the donor site must be considered first. Indeed, the use of wild stocks to supply the demand from restoration has the potential to further damage the remaining populations. In this case, being a first demonstration restoration project in the area, the use of wild stock, already exploited to feed aquaculture plants, represents a good option and the project will ensure that the stock selection process is conducted responsibly and in accordance with legislation and biosecurity protocols. In addition, when needed, oysters will be kept alive in aquaculture facilities at the Ravenna harbour pending sowing on the Base Limestone Reef (BLR). Since the availability of wild oysters cannot always be guaranteed, arrangements will also be made with aquaculture facilities for the supply of certified young oysters, for instance from the oyster farms in Mali Ston Bay in Croatia, which may provide flat oyster spat for the Mediterranean region (Fig. 1). Notably, the creation of a new oyster reef in the project area and its larvae production can be exploited for future and further similar regional projects, ensuring long-term sustainability through the collection of local wild spat.