Restoring seagrass meadows in Basque estuaries: nature-based solution for successful management

Seagrass meadows provide a wide variety of ecosystem goods and services (biodiversity maintenance, carbon sequestration, sediment oxygenation and enrichment, filtering, coastal protection, and nursery area for other species). For this reason, they are areas of high economic development while historically highly impacted by human activity. Therefore, there is a growing need for the restoration and conservation of these habitat engineers as a nature-based solution for climate change mitigation and biodiversity conservation. The Basque Country region (northern Spain) has experienced a decline in seagrass meadows driven by increases in nutrient concentrations and decreases in water clarity. In this region, only 3 out of its 12 estuaries currently host natural intertidal populations of the protected species Zostera noltei. However, there is written evidence of the previous presence of this species in other estuaries within the region. Despite significant improvement in water quality has been observed in most Basque estuaries, these plants show a low capacity for a successful natural recolonization, requiring human restoration planning and implementation. To ensure a successful seagrass restoration a plan is needed which encompasses four phases: feasibility and pre-project planning, project design, pre-restoration tasks, and restoration/monitoring. This work focuses on the first and second phases, which include the selection of the most suitable reception sites and restoration trials. Therefore, a restoration and monitoring plan is proposed for a Basque estuary which includes further involvement of local stakeholders (users, managers) to increase the probability of success.