Abstract
We compiled published data from peer-reviewed articles and grey literature reports, which we supplemented with our own data, to assess the changes in areal extent, cover, and shoot density that P. oceanic meadows have experienced between the years 1842 and 2009 in the Mediterranean basin. Our results demonstrate an overall tendency towards decline in the areal extent, cover and shoot density of P. oceanic meadows over the last 50 years, the period with the most extensive records available. Available estimates indicate that between 13% and 50% of the seagrass areal extent of P. oceanic in the Mediterranean basin appear to be lost, and that the remaining meadows of the Mediterranean may have thinned shoot density by 50% over the last 20 years and have become more fragmented. Considering the changes quantified in P. oceanic areal extent, cover and density, about 6.9% of the potential P. oceanic vegetation would have been lost annually over the last 50 years. The loss of P. oceanic Meadows in the Mediterranean may have led to a substantial (between 11% and 52%) reduction in the capacity of this key coastal ecosystem to sequester carbon over the last 50 years, thereby reducing the carbon sink capacity of the entire Mediterranean Sea. The main causes of P. oceanic Losses were widespread local disturbances, but recently, global disturbances, such as climate change and the spread of invasive exotic species, have also been seriously threatening. Posidonia meadows in the Mediterranean. These findings urgently call for the implementation of management measures aimed at mitigating coastal deterioration by combining local and global actions.
