Intertidal Seagrass Restoration in the Natural Marine Park of Arcachon Bay

Abstract

Seagrass meadows are key coastal ecosystems sustaining a diversity of ecosystem services for people and nature. Arcachon Bay, a 174 km2 semi-enclosed protected lagoon on the southwestern Atlantic coast of France, is home to large meadows of Zostera marina and Zostera noltii. Yet, both seagrass species have undergone a sharp regression in the 2000s under various anthropic and environmental pressures. The Natural Marine Park of Arcachon Bay, the public entity responsible for Arcachon Bay conservation, experiments with active restoration of Z. noltii meadows through seed- and transplant-based restoration. The ER390 project aimed to contribute to Z. noltii restoration by assessing transplantation performances across the Bay to investigate habitat suitability, and to a lesser extent by facilitating participatory seed collection. A protocol to monitor transplants was created and implemented over the summer 2023. Following monitoring findings, most successful tidal flats for transplantation are identified and a set of environmental factors influencing Z. noltii survival and growth is examined. Subsequent recommendations are formulated regarding future monitoring and transplantation. A large quantity of Z. noltii seeds has been collected through participatory seed collection which also contributed to improve public awareness of seagrass meadows, and to harness a sense of stewardship within the local community. Finally, avenues for public participation and information to amplify local seagrass protection and restoration are explored.