Which concrete substrate suits you? Ostrea edulis larval preferences and implications for shellfish restoration in Europe

The European flat oyster, Ostrea edulis, is an important ecosystem engineer that has been progressively disappearing from coasts over the last century mainly due to overexploitation, habitat degradation and disease. It now subject of many conservation restoration programs throughout Europe, including Flat Oyster REcoVERy (FOREVER) project in France. Protecting managing remaining populations become a nature priority because this species able build biogenic reefs, very specific habitats provide functions services. availability suitable hard substrates for larval fixation critical factor during reef-building process. Although natural are short supply, production deployment easy step help oyster reef restoration. present study was carried out improve artificial design composition concrete used them, focusing on impact formulation surface texture settlement field. Nine bio-sourced formulations ten textures were evaluated. number settled larvae counted each substrate reflected their preferences, results demonstrated microscale greater recruitment than formulation, with preferring settle depressions rough rock-like avoiding flat, horizontal exposed areas. Physical mechanical properties different also they had almost no recruitment, these could be helpful (in terms 3D design, durability, manufacture deployment) guide choices materials should proportion granulometry incorporated shells obtain best texture.