Collapsed European oyster reefs must be restored at ecosystem scales

European native oyster (Ostrea edulis) reef ecosystems are collapsed but were once a dominant feature of European seascapes. Recent restoration efforts, while increasing, remain diminutive compared to the ecosystem's former extent and what is required to restore functioning oyster reef ecosystems. A functioning European native oyster reef ecosystem requires larval connectivity at the metapopulation scale to ensure sustained recovery of resilient oyster reef ecosystems and biodiversity. To meet international nature recovery targets, restoration goals must therefore move beyond consideration of native oysters as features of habitats and toward their consideration as biogenic ecosystems, several hectares in size and functionally connected. As member states of the European Union seek to develop their Nature Restoration Plans in response to the Nature Restoration Regulation (NRR), it is critical in the case of European native oyster reef ecosystems, that the recently established historical baseline is referred to, such that native oyster reefs are appropriately defined for future implementation of the NRR and the EU Habitats Directive.