This project aims to quantify the effects of the historical storm “Gloria” on the coastal underwater seagrass meadows of the Spanish coast, especially of Posidonia oceanica. This emblematic and structuring element of the Mediterranean marine ecosystem has a very slow growth (around 1 cm of horizontal extension per year) and is susceptible to massive deaths from aggressive burial and uprooting factors such as those linked to severe storms. The impact, extension and duration of the Gloria storm has been exceptional but the climate change scenarios indicate that the frequency of these events will be greater in the coming years, greatly reducing the ecosystem services that these seagrass ecosystems offer (shelter for other species, water quality , protection of the coast, carbon sink) and jeopardizing its viability. This project seeks to estimate Gloria’s impact on underwater natural heritage and its collateral effects on the services they provide, as well as the relationships between the degree of seagrass meadows fragmentation and their burial/uprooting level.