Historical qualitative information and historical and recent cartographic quantitative information were combined to assess changes in extent and composition of seagrass meadows of Liguria since the beginning of the XX century. Posidonia oceanica lost a total of near 2700 ha, corresponding to 38% of the estimated original extent, while Cymodocea nodosa increased by 44% in the last 20 years, compensating for the loss of P. oceanica in terms of total seagrass extent, but implying the dysfunction of the ecosystem