This study presents a valuation exercise of a specific ecosystem located within the Lagoon of Venice in northern Italy, the island of St. Erasmo, a complex habitat historically generated by the co-evolution of both ecological and economic processes. Mapping the spatial distribution of biophysical characteristics of the island, the authors link the economic assessment to specific areal units, in order to obtain total and per hectar physical, then monetary values. The range of assessed ecosystem services includes recreational benefits (92,320 €/hectare), the service of protection from floods (315,000 €/hectare), the presence of genetic diversity and maintenance of life cycle of migratory species (120,000 €/hectare). Additionally, the paper analyzes the level of co-location and spatial association among ecosystem services and market asset values, in order to suggest a spatially explicit tool to explore the compatibilities and trade-offs among local planning priorities.