Posidonia oceanica is a protected species and the meadow habitat is also protected by legislation. We are not able yet to produce P. oceanica in vitro. All the material used in the restoration projects comes from natural populations, and its collection may interfere with the natural dynamics of the population.
Replanting marine angiosperms, including Posidonia oceanica meadows, does not make sense in any scenario. Ecosystem restoration organizations, such as UNEP or the Society for Ecological Restoration, agree on a series of standards that are applicable to any restoration project.
Why: Reason for intervention
An ecological restoration project does not justify an impact. Any impact on Posidonia oceanica must be avoided or managed to prevent the degradation of existing meadows. Ecological restoration is an action to repair an unavoidable damage and seeks to stop and reverse the degradation of an ecosystem, facilitate its recovery and stop the loss of biodiversity
Where: Site of intervention
There is no agreement for assigning absolute value to different ecosystems to justify the substitution of one habitat for another. Posidonia oceanica restoration must be done in areas where there was an old meadow that is degraded. Otherwise, we would introduce the species in an area where the natural habitat is of another nature and would promote an action of habitat replacement.
The presence of P. oceanica dead matte is an indicator of the previous presence of a meadow in the area, although not all dead matte areas are anthropogenic. Restoration on mobile substrates has until now poor survival results. Regarding rocky substrates, we need to improve restoration techniques to restore degraded meadows on this kind of substrate.
Cause of degradation known, managed or extinct
Before restoring degraded Posidonia oceanica meadows the cause of degradation must be known and such impacts should not be still operating. Replanting in an area with high anchoring pressure if the impact has not been previously regulated will lead to the loss of the replanted plots.
Measure of success: include a reference habitat
The international standards for ecological restoration include measuring the success of the restoration project using a reference habitat (i.e. non-degraded natural meadow) for comparison. Restoring projects for P. oceanica should include quantifiable measures of performance evolution and success compared to an established meadow. The aim of ecosystem restoration is to help the degraded area returns to its pre-degradation trajectory, in terms of biodiversity, structural complexity, etc. Due to the slow development of P. oceanica and the previous data, we recommend follow-ups of at least 5 years.
Need for the intervention
P. oceanica meadows have their own propagation mechanisms. Small areas of dead matte that are integrated into a healthy meadow can regenerate by the plant’s propagation mechanisms (rhizome vegetative growth and natural recruitment with seedlings and / or rhizome fragments). These processes can be more efficient than a replanting intervention.
Does the intervention threat natural meadows?
The collection of material for transplant must minimize the impact on natural recruitment and propagation processes of the natural population. Two fundamental criteria:
Fragments: Replant with drifting fragments. Extraction of material from living meadows is not allowed in the Balearic Islands.
Seedlings: Use seeds extracted from fruits collected on the beach for replanting.
Integrate replanting into a larger-scale meadows management strategy at regional/national level.