The value of the seagrass Posidonia oceanica: A natural capital assessment

This study took place in the Isola di Bergeggi Marine Protected Area (Italy) and consisted of the economic valuation of Posidonia meadows, a characteristic ecosystem of the Mediterranean Sea. To calculate the value of the main ecosystem services, a methodology called “emergy” was used, a quantitative analysis technique that standardises the values of resources, services and non-monetary and monetary products into a single unit. The main services considered are habitat function for various species, sediment retention, hydrodynamic attenuation, primary production and oxygen release. As a result, the sediment retained by the meadow was found to be the most relevant input, contributing up to 99% of the total required emergence and ecosystem services value. On the other hand, economic losses from grassland regression were determined by a temporal comparison of the mapping (1990-2006). The suggested procedure represents an operational tool to provide a synthetic monetary measure of ecosystem services that would be used when comparing natural capital with human and financial capital.

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