The detrimental consequences for seagrass of ineffective marine park management related to boat anchoring

•We measure the effectiveness of marine park management on conservation of seagrass.•Mooring fields and anchoring restrictions are not efficient system in protecting seagrass.•The condition of P. oceanica is disturbed both in mooring fields and in control area.•Anchor scars increase after the tourist season.•Traditional mooring systems have impact on the surrounding area of the meadow. Posidonia oceanica (L.) Delile meadows are recognized as priority habitat for conservation by the EU Habitats Directive. The La Maddalena Archipelago National Park (Mediterranean Sea) P. oceanica meadow, the dominant coastal habitat of the area, is mostly threatened by boat anchoring. 12years after the establishment of mooring fields and anchoring restrictions, a study was conducted to measure their effectiveness on the conservation of seagrass and the mitigation of anchoring damage. We found that: (i) the condition of P. oceanica was disturbed, both in the mooring fields and in control locations; (ii) mooring fields and anchoring restrictions did not show to be an efficient system for the protection of seagrass, in fact anchor scars increased after the tourist season; (iii) the mooring systems had an impact on the surrounding area of the meadow, probably due to their misuse. On the basis of these results, management recommendations for marine parks are proposed.