Relationship between the evolution of the shoreline and the Posidonia oceanica meadow limit in a Sardinian coastal zone

This paper concerns the study of some coastal processes in the Gulf of Oristano (West coast of Sardinia, Italy) for which important environmental changes were observed. Using remote sensing as principal tool, the study, aims at assessing the littoral evolution over time (1977-2000), and at trying to examine whether there is a relationship between the evolutionary trend of the shoreline and that of the upper limit of the Posidonia oceanica (L.) Delile meadow. Obtained results show on the one hand that some portions of the coastline, mainly located on the sandy part of the littoral, have encountered significant variations, and on the other hand that a clear relationship does exist between the evolution of the upper limit of the meadow and that of the position of the facing coast. Mainly of natural origins, this evolutionary trend has also to be related with anthropogenic pressures put on the seagrass meadow. This latter significantly affects the littoral geomorphology, being a provider of biogenic sediments as well as a "brake" acting on coastal water masses.