Diachronic G.I.S. Map of a Cymodocea Nodosa Meadow for Coastal Zone Integrated Management in the Tigullio Gulf (Eastern Ligurian Sea)

Mattia Barsanti (1), Carlo Nike Bianchi (2), Ivana Delbono (1), Ornella Ferretti (1), Carla Morri (2),
Andrea Peirano (1), Olivia Vannello (2)

(1) Marine Environment Research Centre, ENEA S. Teresa, La Spezia (IT)
(2) Dip.Te.Ris, University of Genova (IT)

The temporal evolution of the meadow of the Mediterranean seagrass Cymodocea nodosa in the Tigullio Gulf (Eastern Ligurian Sea, NW Italy) was studied through diachronic GIS (Geographical Information System) map. The study site has a high naturalistic and socio-economic importance, with particular reference to the seafront area of Chiavari, Lavagna and Sestri Levante. The seagrass meadow was investigated in 1986, 1991 and 2001 using previously published and new cartographic data. Data were georeferenced and processed with GIS using overlay vector methods. The system was used for an ex-novo mapping of the meadow of Cymodocea nodosa in 2001, as well as to analyse concordances and discordances in the extent of the seagrass meadow in the three years under study. The diachronic analyses allowed to assess the meadow temporal changes and to carry out a critical analysis of the different methods applied in the three maps. In addition, this study emphasizes the importance of diachronic ecological maps through GIS as a tool for coastal zone integrated management.