Innovative Approaches to Zostera Seagrass Meadow Restoration in the Arcachon Basin: Biomimetic Solutions for Hydrodynamic Control

Seagrass meadows, especially those formed by Zostera species, are critical for coastal ecosystems, providing habitat, enhancing water quality, and stabilizing sediments. However, these meadows have  dramatically declined in the Arcachon Basin since 1989, primaly due to rising temperature. Then a positive feedback loop leads to a global decline as identified by Ifremer studies, which hinder their natural recovery. In response, our project aims to restore these valuable ecosystems by creating hydrodynamic conditions favorable to Zostera seagrass regrowth.

We developed a flexible, biomimetic structure designed to mimic the physical properties of seagrass leaves. This solution reduces current velocities and bottom shear stress, similar to natural seagrass meadows. Initial design and calibration were performed on a small scale, testing various configurations of "leaves" on the field with in-situ monitoring, to determine the optimal size, density and position in the water column for effective hydrodynamic control. Numerical modeling further refined the design, predicting system performance across various environmental conditions.

Pilot installations at larger scales in the Arcachon Basin have shown promising results. Early field data indicate a significant reduction in current speed and bottom shear stress around the structures. Additionally, the altered hydrodynamic environment has already begun showing signs of improved sediment stability and enhanced suitability for Zostera transplantation. These findings suggest that our biomimetic approach could serve as a scalable and effective tool for the ecological restoration of seagrass meadows, offering a new pathway to enhance coastal resilience and biodiversity.