Plantae. Tracheophytes. Angiosperms. Monocots. Alismatales. Posidoniaceae. Posidonia. P. oceanica.... Marine ecosystems are complex, and the biodiversity inhabiting them is huge and dynamic, with patterns and being controlled by the interplay between physical, biogeochemical and ecological processes. Consideration of these interactions and exchanges is crucial to the development and management of human interactions with the sea. Our understanding of the linkages between climate change and anthropogenic disturbances needs to be improved. Marine protected areas are promoted as a tool for marine conservation, but also have potential to contribute to ecosystem-based management. MPAs are usually areas where human activity is strongly regulated or even not allowed at all but current legal definitions of MPAs embrace a range of objectives in relation to species, habitats and ecological processes.