Philippe Potin1, Jean-Claude Ménard2, Raphaela Le Gouvello3, Anne-Laure Barillé4, Amélie Alarcon2,5, Dan Potin1
1Sorbonne Université, CNRS, UMR 8227, LBI2M, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, France - 2Association Estuaires Loire-Vilaine, France - 3STERMOR, France - 4Bio-Littoral, France - 5École de Gestion et Protection de la Nature, France
Brown seaweeds are keystone species of coastal ecosystems, often forming extensive underwater forests, which shape among the most species-rich ecosystems in cold seas around the world. Over the last 50 years, many of the world’s kelp forests, including those in the bay of Biscay, have been in decline.
In this project, a local non-governmental organisation of divers and sea lovers, Estuaires Loire-Vilaine have mapped precisely the remaining population spots of the perennial kelp Laminaria hyperborea, in the Natura 2000 site encompassing the Evens reefs in the Bay of La Baule (Loire estuary, France), focusing on changes in distribution and density during the last 20 years. These studies have shown that increased turbidity and temperatures could be major stressors reducing the size and health of kelp populations.
In addition, in concertation with several scientists, they have developed methods to restore threatened kelp habitats. Pre-matured kelp thalli were collected on site in November 2023 and were used to establish a kelp hatchery at Station Biologique de Roscoff. Adapting the technologies of green gravel and seeding on natural fiber ropes, a group of divers have realized the first planting of kelp plantlets in July 2024. The site of plantation at the Evens reefs is now monitored using a CTD probe and surveyed by benthic studies operated bi-monthly. In addition to monitoring the growth of replanted kelps and algal recruitment, the associated benthic communities will be surveyed using a before-and-after control impact (BACI) design. We believe that this project, which is for the first time attempted in France in kelp forests could be the start of a new way of restoring marine habitats, involving citizens, scientists and local stakeholders, which could upscale the restoration efforts.
Biography
Philippe Potin is a seaweed biologist and biochemist. He currently serves as Scientific Director of the Global Seaweed Coalition and Chair of its Scientific Council, and works as a Senior Scientist at CNRS in Roscoff. He is involved in large international projects to develop the sustainable development of seaweed-based regenerative aquaculture and restoration of declining kelp forests.